Varying Frequencies

Thor's Hammer back on track

2011-09-27T21:23:00.003+02:00

Thor's Hammer has been down for a while due to a thunderstorm putting it offline.
The grabber is on line again.

If I have sufficient time one or two new bands will be added to TH when I go there next time. 80m is a likely candidate, since I have a 80m RockMite built and ready. However, I may have to add another low powered PC to take the load off the current one. SpectrumLab is not the easiest on processor load.

I may see if Argo or Spectran is better in that respect. Tests needed, or, if anyone has experience, please tell me.

Thor's Hammer up and running

2011-01-17T13:26:00.004+01:00

During some work at the place the PC had been switched off.

The "Hammer" is running nicely again since Christmas.

It is running on 10MHz and 500kHz as before. Possibly with an extension in a few months. Some antenna work and some soldering needed.

Next band will probably be 80 (3500kHz). and a simpler receiver for 10MHz. The original receiver will then be set to yet another band. Some wideband antenna work will be necessary for this to work out.

Time to get the soldering iron warmed up again.

On the PA9QV front the next soldering project should be the FA-SDR. All components including the housing have arrived, only a PA (1W) is missing yet. I may build a small wideband PA myself.

Still a lot of kits to build, but slowly getting started again.

Thor's Hammer stuck

2010-11-20T01:11:00.003+01:00

I have noticed that Thor's Hammer has stopped uploading. Reason unknown, but could be the Inet connection has been lost, or the PC has been rebooted due to a power outage. I will have to wait and see.

Since I cannot just go there and back again in a day It will have to wait till I can go there for it to be updated

New kits arrived

2010-10-26T21:42:00.008+02:00

It took a while, but I now have "a few" kits to build.

Some SoftRock II kits, different bands, each can be made directly for 160,80,40,30 or 20m, all components in the kit. Some SMD soldering necessary, but should be possible, even with my eyes.

Some "Funkamateur" single frequency kits, among those a 10.7MHz kit to connect to my VHF-UHF RX (R7000, possibly AR-8600).
Two kits for 9MHz, one will be modified for use on 10MHz

the other 9MHz might be made "wideband", so a multitude of LO signals could be used, possibly a Si570 synthesizer or the DDS60 kit

Two lower band kits, to be decided

The FA wideband SDR TRX, will need a PA and a programmable LO, not yet ordered. Covering 1.7 - 30 MHz with preselection, so seems quite usable.

The "standard" 1W PA could probably easily be replaced by a home made solution, but I will see if I do not get to order the standard one at some stage. The local oscillator, the so-called FA-SY may be the way to go for full band coverage. A housing is also available, I may order that one, too.

Update :
The FA-SY oscillator has been ordered, along with a housing fit for the FA-SDR TRX
More Update :
The FA-SY kit and the housing have arrived

Lots of kits to build, not too much time, so let us see what comes up here.

The intention is to use some of the fixed frequency stuff for simultaneous WSPR and QRSS monitoring.

600m WSPR at "Thor's Hammer"

2010-10-12T22:04:00.002+02:00

Since I visited the QTH of OZ9QV last month I have been monitoring the WSPR reception there.

The WSPR receiver is of course the same as the one for QRSS, with WSPR running concurrently on the PC.

With the tiny indoor tuned multi turn loop (diameter 22cm) the following stations have now been received successfully on 600m .

PA0A, PA0O, G3XIZ, PE1GRL and EI0CF being 1225km from there.

For such a simple setup I am quite happy with the results, even though I know that improvements are certainly possible.

Grabber : "Thor's Hammer" at OZ9QV : updates

2010-09-25T14:53:00.008+02:00

During a holiday (and being there for other reasons) in Denmark I have made an update to the "Thor's Hammer" QRSS grabber. More will happen later at another visit.

The grabber can, as usual be found at :
Thor's Hammer

The grabber now works on two bands, a more stable receiver (old TRX with defective TX) has been installed for 10 MHz and the viewable frequency range reduced. Still using an older low powered PC

10 MHz Grabber :
RX range : 10139.880 - 10140.120 kHz
SpectrumLab set for display of 3 stripes of consecutive periods
Antenna : indoor dipole

500kHz Grabber :
RX range : 502.700 - 505.500 kHz - some noticeable frequency drift, but acceptable
SpectrumLab set for 3 strips as above
Antenna : indoor multi turn tuned loop

The 500kHz RX seems to have some problems with receiving WSPR, only once or twice the WSPR signals from PA0A and PA0O have been received.
The signal from (I think) G3XIZ was visible, but no decodes.

All in all I am fine with the improvements, but more is needed. I would like to add more bands, e.g 80m, 40 and 20m, possibly 136kHz but things do take time to get running, and new antennas will be necessary.

I may experiment with a wide band active loop antenna (H-probe) or an E-probe (short active whip).

Simple 80m Grabber Receiver Ready

2010-08-29T19:54:00.003+02:00

Next time I will visit the OZ9QV grabber "Thor's Hammer" there will be another band active in grabbing : 80m

I have finished encasing a modified RockMite 80 (RX only)

Frequency drift is acceptable :
10 deg C : 3499.955
23 deg C : 3499.915

Yes - negative temp coefficient.

Since the temperature is expected to be within that range (most likely 15 - 25 for the majority of the time, and I expect to put the RX and PC into a cupboard, I would expect the local oscillator to stay within 3499.925 +/- 10 Hz for most of the time, quite acceptable.

The addition of another band to the grabber is worth it alone, I think.
New antenna needed as well.

I know that more activity is on 40m by now, but the winter should be good for 80m experiments.

The grabber is expected to run with an older, low powered PC, together with the 10 MHz grabber.

The new grabber receivers should be installed before the end of the year.

I am playing with an idea for a more stable grabber receiver for 3500/7000/14000 kHz, more on that later.
It will be a bit more complicated to build, so I will be taking my time.

Thor's Hammer again

2010-08-23T13:40:00.004+02:00

Yet another alignment,

The receiver is drifting quite a bit, so the 'window' has been widened to 550 Hz, at least some signals are visible.

Further improvements to the grabber will happen later.

Thor's Hammer with frequency drift

2010-07-31T21:26:00.002+02:00

The receiver has a considerable frequency drift, even more than I expected.

When I visit next time I may have a better RX at hand. - if there is enough time to ge one going.

Thor's Hammer Realigned

2010-07-26T19:27:00.002+02:00

I was visiting the house of OZ9QV and got the 10 MHz grabber realigned.

I broadened the viewing frequency window, since the receiver has some temperature drift. In any case, QRSS signals are now visible again on the grabber.

Thor's Hammer, by OZ9QV :

QTH JO65cp
Frequency 10.140 MHz
Cheap transistor synthesized receiver
Older low spec PC

URL :
http://www.xs4all.nl/~jgander/qrss-p/

Update IC-703 500kHz

2010-07-15T16:17:00.002+02:00

After having made a study of the IC-703 manual I see that there is a high pass filter in the TX path , cutting off at 1.6 MHz.
This is most probably for avoiding the IF frequency (455kHz) reaching the TX output.

A switch - switching in a 500kHz bandpass filter (alt 136kHz filter for LW) or bypassing the filter - would probably be possible, but the *tiny* SMD components at this place in the radio makes me think twice about making the attempt.

It *may* be possible to tap the signal out to an external amplifier, but then there is still 30mW out of the TX at 500kHz, so that could as easily be used.

Conclusion : 500kHz looks possible with the 703, but I doubt the internal filter mod is worth the risk of ruining a perfectly good TRX.

Modifying the IC-703 - - and 500kHz

2010-07-11T14:46:00.005+02:00

Ham radio manufacturers are funny (funny-strange, I mean).

They make 100 W radios needing lots of cooling, yet the PA's work through.

On the other hand, making QRP radios, PA transistors go KAPUT, drivers go KAPUT (FT-817 and IC-703 respectively)

SInce I have a FT-817 with a PA that died, I know it is just a matter of time before it happens again, unless the correct mods are made.

This week end ( with temperatures up around 30 C) I got to do the necessary mods for the IC-703

1) Driver modification. This one is not too bad, a matter of cutting a single PCB track and rerouting a piece of wire on the accessible side of the PCB, no need to remove the PCB. When at it, I adjusted the bias to the driver down to the recommended .5V, so the driver should be safe even with high temperatures now. In the original IC-703 the driver is connected directly to the full supply voltage, now it is connected to the 8V supply line.

2) CW Keyer input. For some obscure reason the keyer jack is grounded through a choke, giving rise to RF making it impossible to release the TX key. The solution, connecting the keyer jack ground directly to RF ground can be made provisionally outside the radio, but the more elegant solution requires the main board PCB to be lifted from the housing. Not too tricky, but beware of the flat cables (connectors).

3) 500 kHz TX option. This one required moving a *tiny* SMD diode. I managed to do it with a "normal" small solder tip, but the result is not that pretty.
The mod does open for TX on 500 kHz, but max output is about 40mW, and it looks like something is heating up, because the output reduces a bit after key-up, then stabilizes. I would probably not try to use the max output, but reduce it a bit, them make a power amp.

All in all not too bad for a hot summer's week end.

New Toy, Heavy Stuff

2010-07-06T22:09:00.003+02:00

Just picked up a Maritime transceiver, the IC-M710.
The station operational from 1.6 to 30MHz, so TX on all bands 160 - 10m.

Now I need to learn to operate the thing, it is not quite the same as a normal HAM transceiver, but there will be time for playing, the set tunes in 100Hz steps, but with a clarifier.

Capable of running 150W out continuously (I have heard), the radio can be used for heavy duty operation

Now for some playing...

Crystals and oscillators . . .

2010-06-19T15:05:00.004+02:00

For some time I just had a few boxes full of crystals and oscillators- some found at ebay, others at rallys etc - not very practical when trying to find a particular one, or know which ones I have.

So the last week I have sorted out a bit, so that crystals with standard values (and in large quantity) have been separated into their own drawers. Others have been grouped in similar frequencies. some are still left unsorted, but that will have to wait.

Now to make a list of what I really have.

The idea is to write a small program for calculating possible uses of the crystals I have - for simple single frequency (or vxo controlled) receiver or transmitter circuits. After all, not all TX/RXs need to be DDS controlled. Yes - I know that there are lists out there with frequency combinations from standard crystals, but I have some additional frequencies in my stock, so will have to figure those out myself.

At least I got a *little* bit more order in my very messy shack ;) - even if I could use some more sorting out - that will have to wait.

DDS-60 has arrived

2010-06-19T11:21:00.003+02:00

Just received a DDS-60 "daughter-board".

Now will be the time to look into getting the DDS programmed, there is no controller yet.

For very simple stuff a PIC or PICAXE processor programmed in BASIC will probably do. For more functionality (and mor memories) I should probably go for a more advanced processor. IFor that I consider the Arduino project, using AVR ATMEGA processors. It uses a variation of C (with a limited functionality and special commands for controlling I/O pins), something I have not yet done anything with, but is it ever too late to learn ?

Arduino is an open source project, so even the bootloader can be loaded on to a processor without one, unlike the PICAXE bootloader which is proprietary. I now have an Arduino board and a few processors on the way.

More to think about, more to try out ...

This summer I also have a large reading project going on, so a bit less radio building activity is expected.

Enter the DDS

2010-06-13T16:04:00.002+02:00

Just received a kit, the DDS-2 from N3ZI.

The kit contains all parts, including a simple display, for making a functional DDS.

The kit is relatively easy to assemble, all parts were present. The SMD integrated DDS chip is somewhat more tricky to solder without creating solder bridges. I think the pads are a bit wider than the pads for the NE612 SMD mixer on the Rockmite/Warbler kits from Small Wonder Labs.

First the bad news : Tuning the DDS-2, as it is, is an exercise in patience. it is slow, when trying to use the fast function (turning the knob faster), the tuning becomes erratic. The lack of a keyboard entry function is serious with such a slow tuning.

It looks like a modification of the firmware should be attempted. Quite a daunting task, given that (as far as I know) the source code is not available, and my programming skills are not that good.

The good news is that the temperature stability looks fine. the crude "switching on and off the fan" method revealed about 20 - 25Hz drift on 10 MHz, of course relatively less on lower frequencies. For a non- temperature compensated clock oscillator this feels quite good, and I would expect better stability when the DDS is boxed.

Other good new on the DDS-2 : even if tuning is a bit of a pain, there are two redeeming qualities :

- the standard firmware has 10 "memories", acting like the "Band stacking" feature of many modern transceivers. so a multi frequency MEPT with 10 (11) pre-programmed frequencies is quite doable

- the application of the RIT should be quite useful for generating FSK easily, eg for a relatively frequency agile MEPT.

However, for more experiments I did order a DDS60 daughterboard that should be programmable from a PC or an external (PIC, PICAXE etc) microprocessor board.

More RM30 info

2010-06-06T19:04:00.004+02:00

The RM30 was tested a bit this week end before the shack update, and the results look encouraging and disappointing.

The sensitivity of the RM30 looks really good, noise increases more than 30dB when a piece ow wire (in the shack) is connected, indicating sufficient gain for a grabber.

The frequency response shows the unmodified RM30 to have a slightly too low peak frequency, about 1kHz, so next test will be a (variable) capacitor in series with the input crystal, the main problem is mounting it on the PCB.

The frequency stability, however is not nearly as good as I would want. I may have to get some of the clip-on heaters that DB6NT has for sale, but initially the RM30 will be boxed and thermally insulated.

Update :

47pF in series with the input filter crystal brings the peak (rather broad) up to 10140.5 , this is quite acceptable since the bandwidth of the filter is about 1 kHz in the RM-30 setup.

Shack update

2010-06-06T18:52:00.002+02:00

Some time ago I moved the shack from the "attic" position, especially because it gets extremely hot up the in the summer and very cold in the winter. Also the mess there is "rather visible".

Today I was digging out some of the test equipment from upstairs, so the shack downstairs is now sort of usable. The soldering iron was , of course there already, but now I added my Lab power supply, oscilloscope, frequency counter is now set up, as weel as an old "Bolometer" for RF power measurements. oh yes, a step attenuator from 1 - 110dB is not bad to have in the shack - and an ancient AF signal generator. An old digital multimeter running off mains seems to be out of service at the moment, but a portable one will have to do for now.

The RF signal generator, running from 10 - 500 MHz is not that good for SSB/CW measurements, but will have to do for now. It seems I should build a DDS or synthesized RF generator and just use the external attenuator.

And finally the heavy equipment : a spectrum analyzer, yes old surplus, but looks like in working order still, all will now have to be powered up some time every day to make sure it does not burn out.

WSPR BFO offset test

2010-05-31T11:59:00.002+02:00

Tried the BFO offset function on the WSPR2 program.

Using the FRoG receiver I set the USB frequency to 10137.490, same in the WSPR settings, and set the BFO offset to 1710Hz in place of 1500.

Spots are coming in nicely on 10MHz with just a piece of random wire indoors.

Later : tests with the RM30 grabber rx input filter, and see if sensitivity is sufficient - then some compact antenna.

RockMite 30/80 Update

2010-05-30T19:01:00.006+02:00

I have run a simple test of temperature drift of the two RockMites :

Using a fan blowing on the PCBs lying on the desk the RM80 drifts less than 10Hz when the fan comes on or off for about 5 minutes, that is quite acceptable, given that the RMs will be boxed, and likely I will use some insulating Styrofoam.

The RM30 is a bit more tricky. I tried to lower the frequency with a choke in series with the tuning trimmer capacitor I mounted, and the drift with fan was about 50Hz at on/off.

It turns out that grounding one side of the crystal resulted in a frequency of 10138.490. Not ideal for WSPR, but should be useable with WSPR2 and "BFO offset". Not tested yet, but will be in the near future. Temperature drift at the fan on/off is now 20Hz, and with a bit of insulation that should result in an acceptable temperature stability.

It looks like the drift is more due to the capacitors in the oscillator than the crystal in itself.

Oh, and I am a bit disappointed that the RMs have several zener diodes, but the oscillator itself runs from the raw supply voltage. Where did that idea come from ? I find it surprising that there is not more stability problems with the LO in the RMs

Next step with the RockMites : input crystal filter tuning - if necessary.

RockMite 30 Experiments

2010-05-23T22:47:00.002+02:00

In addition to mounting all but the inductors and transformers for 80m the Warbler and a few more components for the 40m WSPR Warbler I have built a RockMite 30, for use as a Grabber RX only for 30m.

The evening welt with getting the Local oscillator (10.140MHz Xtal) down to 10.138.700. This is done by bypassing the frequency switching, using a simple serial connection of a 10uH inductor and a variable capacitance ( 12 - 30pF ).

The input Xtal filter will be added later, after stability test of the local oscillator, and will probably be a simple SIngle Xtal tunable filter.

Tomorrow will be busy with some non radio activities, so progress will be much slower than it has been this week end.

Warblers update

2010-05-23T00:02:00.002+02:00

I have made myself busy today, mounting the vast majority of resistors and capacitors on my two Warbler kit PCBs.

Tomorrow I should be able to get at least one of them in good receiving order, I will try to make that the 40m WSPR one.

We will see how things go.

Sporadic E Season and 10m

2010-05-19T10:35:00.003+02:00

At the start of the sporadic E season I have retuned my main grabber to 28.321/28.322MHz , still retaining the secondary image for 500kHz.

The 28MHz grabber is using a FT-817 and the 500kHz grabber is still using the ATS909.

As per the previous post I am in the slow process of building more (simple) grabber receivers and some WSPR equipment for 500kHz and several HF bands, at least 3.5, 7 and 10 MHz.

I am interested to participate in the 160m WSPR summer project, so looked for a suitable set of Xtal frequencies. It looks like 9MHz, BFO 8999.5 (I have a Xtal filter, or could probably use some 9 (27) MHz Xtals) and 7159kHz, pulled a down about 4kHz, this should work.

I may need to add sound cards to the grabber PC in order to monitor more than two frequencies.

RM80 update

2010-05-17T22:07:00.004+02:00

I have been operating the soldering iron and modified the RockMite 80 for 3500kHz.

The kit will be used as receiver only, so I bypassed the crystal tuning, ending up on a LO frequency around 3499.920, nicely suited for a grabber on 3500.800kHz

The receiver is probably not too sensitive, so I intend to test it, first with my 30m tuned loop, then most likely with an active antenna of some variety.

The first test has been monitoring the drift of the LO, it looks fairly stable, so a later test will be the rx sensitivity.

Next on the workbench will be the 80m Warbler, usable for PSK31 (of course) and a grabber on the colour burst frequency. I will be building it exactly as intended in the original design, then later build another for use on 40m WSPR.

QRSS Grabber in OZ

2010-05-08T20:48:00.006+02:00

This week I have been in Denmark on Holidays.

During this I have set up a grabber receiver at the QTH of OZ9QV

The receiver is a simple one running on the 30m band, 10.140.0 - 10.140.1

QTH : JO65CP

Antenna : Indoor dipole (I don't want to risk too much in thunderstorms).

The system is running SpectrumLab and ArgoUpload, as well as WSPR in receiving mode

I hope to keep this running 24/7, but no guarantees, Internet may go down, power may be out, etc.

I hope some people will have fun using this grabber, and will try to get a bit more up and running there at a later stage.

Update : the OZ grabber seems to lack sensitivity, but is still operational.

WSPR on the Mac

2010-03-29T11:39:00.003+02:00

This past week end I have, among other stuff, made a few attempts to get WSPR running on a Mac running Snow Leopard.

Tried a few "Tips and Tricks", using MacPorts and other stuff but none of the tricks were useful.

I was finally pointed to a HowTo for making the install, and this is what will be going on next in that part of the story.

SpectrumLab seems to be running under Wine for the Mac, so it looks like that part is usable.

Fldigi exists as a package and runs, if a bit touchy in the user interface.

Update :

WSPR installed mostly according to the guide, but only on a pristine installation. Not ideal. Thanks to G4KLA for assistance. Now I need to see if I *can* get it installed on my already installed system.

One problem, however : While the >WSPR program starts and runs, it exits at unexpected times with an input overflow message, so not very useful for long term deployment. Back to using Windows for WSPR. (Or possibly Linux, will have to be tested)

Active antenna experiment.

2010-03-14T19:59:00.002+01:00

Having visitors this week end put a limit to my radio activities, but one thing got done.

I built (did not take that long) a small balanced amplifier with a TL592 IC. The aim is using it with small loops and ferrite antennas.

The amplifier can be found at Low Frequency Antennas , I made it for a bit higher gain and with a manual tuning capacitor in stead of the varicap, but essentially everything is as in the circuit diagram.

Going through resonance on 80m and 160m the noise increases by 20 - 30dB, so the noise figure and amplification looks good. It looks like the amplifier will support even smaller antennas than my 80-160m tunable loop.

Further experiments with the amp. should include smaller loop/frames and ferrite antennas. It could be interesting to see if the small (50 - 60mm long) ferrite antennas from small transistor radios will work in the indoor noisy environment, or even what they will do outdoors in the open (less noise)

A bit of 500kHz experimentation

2010-03-07T20:23:00.004+01:00

The new cardboard box frame antenna with better wire turns out to be a bit better. A few dB increase of S/N has been gained.

The loop was at first connected to the HF-3 receiver, and gave some WSPR spots from local stations like PA0A, PA3EGO (also seen with QRSS) and PA3FNY, with relatively good signals if considerably lower than Joachim gets with his Octaplumb. Also G4JNT during night time and one or two other spots from G stations. All in all not very impressive, but not too bad for an antenna inside the noise field of the apartment. Also every night DI2AM with QRSS, and occasionally a good signal from OK0EMW.

A test with the ATS909 receiver, using just the built-in ferrite antenna gave surprisingly good results, almost as good as the cardboard loop with the HF-3, with DI2AM in every evening.

Test with the FT-817 gave a marginal improvement over the HF-3, maybe 1 - 2 dB.

Test with a FRG-100 receiver showed that the receiver is considerably more sensitive than the FT-817, but due to "antenna noise" (apartment noise) the improvement was again marginal, 1 - 2 dB.

The antenna has now been moved upstairs, still indoors, and another 1 - 2 dB has been gained. interesting to see how much signals will come from the G stations now.

An improved loop for outdoor mounting, like Joachim's Octaplumb will be built here, and some tests with larger transmit antennas are in the plans. Well, and a TX, too, probably beginning with some 50 - 100 mW, so ERP will be in the microwatt range.

This week I am having a visit from a friend staying over, so not much time for building activities, but after that it should go on.

I still have some experimentation on the Rockmites and a Warbler, so more than enough to do here.

Also some experiments with the TL592 amplifier for active antennas (LF,MF,HF) is in the thoughts here, such as variations on the antenna from this site

Some experiments on the (V)XO of the RM80

2010-01-30T14:26:00.005+01:00

After Joachim's experiments with the RM80 frequencies and MEPT, using the varicap, giving some problems with chirp I decided to try another approach, and we will see what the results are.

In place of the varicap I mounted a trimmer capacitor, in parallel with the R10 (feeding the varicap through I mount a 2.2nF capacitor, so that Q2 creates a RF-short of the trimmer capacitor, giving rise to the lower frequency RX LO of about 3579.350.

Just trying, and as expected the oscillator does not oscillate on the stray capacitance of the circuit without any capacitor in stead of the varicap.

First test was with a 2-10pF trimmer, giving rise to a frequency above 3580 (even with full capacitance), and stopping oscillation at low cap. values. Not good enough.

A 2-18 trimmer with a parallel fixed capacitor of 10pF is better : the (high) frequency range is now about 3579.75 - 3580.10. I noticed that the oscillation on the higher frequency is weaker on the higher frequency by about 10 dB, still the oscillation holds. A lower value coupling capacitor to the buffer, as Joachim indicates, is probably in order.

This makes me think that it should be possible to replace the trimmer with another varicap with lower capacitance than the one supplied., and with a zener stabilized voltage make the tx frequency tunable. A range of about 250 Hz should be attainable with one or two BB105 diodes - and I should have some of those somewhere.

On with the experiments, I will leave the RM80 with the trimmer cap for a while and see if the TX frequency remains stable when transmitting.

Update :

The lower value coupling capacitor to the buffer increases the oscillator frequency by 50 - 100 Hz - the oscillator now tunes down to .830 .
Parallel capacitor changed to 22pF, trimmer still 2-18pF, tunes (upper frequency) about .760 - just above 3580.000. nice range.

Rock-Mite 80 update

2010-01-25T20:48:00.004+01:00

A new crystal in the oscillator brought the lower frequency down to 3579.350. That is quite acceptable for a grabber, the audio range for the 3579.500 - 3580 will end up at 150 - 650Hz. Not ideal, but workable.

Here is what it looks like with a few minutes of low - high - low frequency :

Still, with the 5V shift the TX frequency only went up to 3579.500, the shift is just too low at 150 Hz.

Enter the Q2 switch transistor and the 12V pull-up resistor. Voila, the upper frequency is now 3579.850, a 500 Hz difference, bringing the TX frequency just inside the 3579.800 - 3580.000 band.

It looks like it will be a good idea to have more than 2 crystals on 3579 for this construction, so a selection of the most suitable frequency can be made, alternatively find a better suitable varactor diode with more capacitance variation at 0 - 5 V.

The other point, with the current (original) "firmware", the RM starts up at the higher frequency rx local oscillator and will have to be switched manually to the lower lo frequency.

Later the test of the receiver as such, enough done for today.

I am optimistic that this will work as a MEPT tx and Grabber rx, but the rx test will show.

Rock-Mite 80 Initial Test

2010-01-24T22:01:00.003+01:00

The RM-80 is essentially assembled, first test has been done.

As opposed to Joachim I have only 100 Hz shift between the two steps, that is not enough to be useful. This has to be a fault, and I will seek it out later this week.

Rock-Mite Kits Have Arrived

2010-01-23T15:42:00.002+01:00

In the mailbox I found a nice little package today :

Two Rock-Mite kits , one for 80m and one for 30m.

This week end I see soldering in my "crystal ball"

Now which one to begin with ? .... well I started unpacking the 80 kit, so 80m it will be, most likely the color burst frequency around 3579.5 kHz.

DI2AM reception on 505 kHz

2010-01-20T19:48:00.003+01:00

The 500 kHz grabber is now set to two narrow frequency ranges, the "WSPR segment" and 100Hz around the frequency of DI2AM.

DI2AM reception seems to be there essentially all the time after sunset, albeit with some (expected) QSB, and WSPR signals coming and going.

Nice result with a "cheapo" frame antenna wound on a cardboard box 35x40 cm small.

A new somewhat bigger frame antenna (more than 70x70cm) will be made some time, but that will have to wait.

In the week end the construction of the 500 kHz TX should begin

500 kHz transmit permit

2010-01-19T21:07:00.003+01:00

Today I received a permit for experimental transmissions on the 500 kHz band, 501.000 - 504.000 kHz.

Now I will need to build a transmitter, I will most probably go the way Joachim proposed, using a 27 MHz crystal on the fundamental frequency (9 MHz), then dividing by 9 with a 4017, then by 2 with a flip-flop, followed by a "buffer amplifier" , and later an IRF510 as power amplifier.

The hard part will be the antenna, it needs to be compact, so a "magnetic loop" is probably the only way to go here.

Rock-mite kits

2010-01-19T18:15:00.003+01:00

A discussion with Joachim today made me go buy some more kit stuff.

The Rock-mite kits look very suitable for a simple QRSS modification , as seen on Joachim's blog.

I ordered the 80 and 30m versions, one of each.

The best thing is that it is useful as both a grabber receiver and a QRSS MEPT - and the price of $32 a piece to have it sent here should not discourage anyone from doing QRSS.

The Rock-mite is a simple crystal controlled CW transceiver and can be used as such. It is a single frequency device with a crystal as the input filter and another one as (VXO) local oscillator/TX oscillator.

160m - 80m Experimental Loop

2010-01-18T21:49:00.003+01:00

Yet another receive loop is born.

The construction is similar to the first 500 kHz loop, i.e. cardboard box loop, but made with Litz wire and with only 6 turns.

The calculation of resonance frequency found here indicates a frequency range covering the whole of the 160m and 80m band, and this looks like what I have.

The coupling is made with a further full loop, and it looks like that creates a too hard coupling to the antenna (not really unexpected), making the antenna rather broadband.

Later this week some experimentation on the coupling loop size is in the planning.

Better antennas for LF/MF

2010-01-17T19:53:00.003+01:00

In order to make loop/frame antennas with higher Q for the low bands (160m, 600m, 2.2km) I have ordered some Litz Wire from across the "pond".

It will be interesting to see how much improvement I can get from this.

"eBay" , of course. It can be a dangerous place, but it is our last, best hope for strange raw materials.

TVEPG up and running from The Netherlands

2010-01-16T10:56:00.004+01:00

I got the TVEPG set up with the HF-3 and the 500 kHz antenna, you can find it at here

The grabber is running on an Acer Aspire One 110, the old model with 8 GB SSD, under Linux, running SpectrumLab under Wine and an upload shell script originally written by Allan OZ5AR.

The frequency range is set to 503.5 - 505.5 at the moment, but I do have another setting for the 500 kHz WSPR band.

Update :
New setting for the 500 kHz Grabber : split screen with WSPR segment and a wider segment shown together.

500kHz antenna connected to the HF-3

2010-01-15T22:39:00.003+01:00

The antenna is now connected to the HF-3 and receiving there. DI2AM is visible, if not too strong. Some WSPR signals are easily visible, with the WSPR program they should decode nicely.

For now I will leave it running, and in the week end the 500 kHz system could come on the TVEPG grabber page. no time now, and tomorrow some non-radio activity.

Still the signals are not all too strong, so a better antenna is required here.

The noise levels, however seem very low here.

"Progress" report 500kHz RX antenna

2010-01-15T21:22:00.005+01:00

Well - let us say - the antenna tunes down to 500 kHz, but the output looks lower than I get from the ferrite antenna of the ATS-909. The S/N, however sounds like it is better.

The source of the lower output ? I am not sure, but suspect the small size of the loop contributes, and perhaps the coupling winding is not enough with a single turn. further tests are needed.

OK - this antenna is rather small and uses standard hookup wire, so the highest efficiency is not to be expected. a somewhat larger antenna, say 1x1 m made from Litz wire should provide substantially better results.

The first test was with a "dual gang" variable capacitor, but with only one plate set used. of course the hand capacity detunes the antenna so it is essentially untuneable.

SO the second test was with both plate sets, and now we are getting there. because the hand is at the center of the capacitor, no detuning or hand capacity effect is noticeable.

With the 25 windings, the antenna tunes down to just under 500 kHz, so the antenna is a qualified success.

The ATS 909 seems to have a rather good sensitivity on MW, so it is a bit difficult to fully judge the efficiency and usability of the antenna.

The tuning is not *very* sharp, but with a decent maximum at resonance.

The next test should be connecting the antenna to the HF-3 RX which should have a very high sensitivity on 500 kHz. Oh, now for soldering another connector to the cable and see what it will do.

Another solution to the low output could be to build an amplifier, but that sort of defeats the purpose of a 'simple antenna'.

More room for experimentation.

500 kHz Receiving Antenna in the Make.

2010-01-12T21:04:00.003+01:00

I have been looking into the options for receiving amateur signals on the 600m band (500 kHz). Since I live in an apartment size does matter, so looking for a small sized antenna I looked around and found this article from VK2ZAY , showing a simple 'frame antenna' made with a cardboard box.

Being close to all kinds of noise sources I think the loop is probably the best option for a receiving antenna on such a low frequency.

Since I intend to use the antenna indoors the support material does not matter much.

The box measures are on the small side - 35x40 cm (14x16 inches if you like) - but as a proof of concept I have put 25 windings with taps at 15 and 20 windings, as well as a single winding coupling loop.

Now I will be looking in my junk box to find a suitable variable capacitor to complete the project (this may take some time).

If this works out to my satisfaction I will try out frame antennas for 80m, 160m and 2.2km as well, at some time.

Since there seems to be an experimental license available here in The Netherlands I may even try to put out a 600m signal, yes, I am considering joining the experimental group. The decision, however, has to be made soon before the opportunity expires.

Idea Box : Direct Conversion RX for Color Burst Frequency Grabber

2010-01-09T18:13:00.007+01:00

Using 3.579 crystals as crystal oscillator and filter for a PSK31 receiver/transceiver is well known. Getting a decent sideband rejection with a simple circuit is not easy with this design.

Here is a thought : One of the reasons for the lower sideband rejection is the proximity of the 'BFO' frequency to the signal frequency. Possibly oscillator phase noise is contributing to the problems. Here is a trick for a simple QRSS receiver for 3579 :

N4ESS has crystals on 3575.6kHz this is quite a bit further from the signal frequency than is easily done with 3579 crystals. OK, the beat (AF/'IF')then is at about 4kHz, but using SpectrumLab that is not really a problem, since it can 'convert' and filter signals. Of course, the input filter as in Joachim's 30 QRSS Grabber RX is necessary to get some unwanted sideband suppression.

This should make for a simple design for a DC RX Grabber for the color burst frequency on 80m.

Edit : I looked in the 'stock' and I have a 3575.6 crystal (and of course 3579.5 as well, so building this rx for color burst rx is possible. Other projects come first, such as finishing the setup of the 80m SDR from Box73.

Note :

The same concept should be usable with a 160 RX at 1843kHz with a 1856kHz Xtal, also available at N4ESS, albeit with a somewhat higher 'IF' of 13 kHz.

Idea Box : Simple Two Band Grabber Receiver

2009-12-26T21:42:00.002+01:00

This could be extended to 3 or 4 bands with some effort, but here is the basic idea :

I have some Crystals on 3500 , 7000 and 14000 kHz. This could make for an easy setup of a dual band grabber using a single local oscillator :

Here is the trick :

- make a single oscillator on 3500 kHz
- use two buffers (possibly use the gates as buffers)
- take one signal and use a direct conversion receiver circuit on 3500kHz, using the crystal filter of Joachim's QRSS receiver

- take the other signal and use the 3500 kHz LO signal for a receiver almost exactly as PA1GSJs receiver,

- making it a *simultaneous* dual band grabber receiver for :
- 3500.800 - 3500.900 kHz
- 7000.800 - 7000.900 kHz

Of course, the same idea could be used to make a 7000 / 14000 kHz dual band grabber receiver using 7000 and 14000 kHz Crystals.

There is even the option of making a doubler for the 3500 kHz signal, using this for extending the dual band grabber to a 3-band grabber for 3500/7000/14000 kHz.

Actually Joachim and I have been talking about the 3-band idea, but I have come to think that the 2-band idea is better in terms of simplicity of construction

Idea Box : Long Wave SDR

2009-12-26T21:20:00.003+01:00

I found those 4.224 Crystal oscillators (ex equipment) on eBay .

Divide 4224 by 32 (first 8 and then make the quadrature signals), and the LO frequency ends up on 132 kHz. Not bad for a 136 kHz SDR.

Idea box : 10.7 MHz spectrum scope (1)

2009-12-26T20:49:00.005+01:00

I found a nice crystal frequency on eBay : 10.6875 MHz

Yes, 10700 - 12.5 kHz.

Combined with a 15 kHz wide 10.7 MHz FM filter and a direct conversion receiver this should make a 10.7 MHz spectrum scope with 15 kHz bandwidth, so :

10.7MHz signal from R7000 or similar receiver -->
possibly a preamplifier, in any case some termination for the filter -->
10.7MHz FM filter for 25kHz channel spacing (BW = 15 kHz) and 2nd termination -->
DC-mixer with oscillator frequency of 10687.5 kHz (possibly pulled up to 10690 kHz) -->
AF amplifier -->
output to PC running spectrumLab

Looks like yet another 'little' project.

should be good for looking at satellite transponders with (not too wideband) digital signals, and some Doppler tracking at the lower satellite frequencies.

TVEPG in JO65CP now on 40m

2009-12-24T11:46:00.004+01:00

The TVEPG has been set to monitor 40m. QRG 7059.850 - 7060.050 kHz

Colin, G6AVK is coming in nicely with his 500mW into a dipole.

The TVEPG will be running mostly on 40m during daylight hours, for the next few days.

TVEPG success : G6AVK strong tonight on 80m

2009-12-22T22:56:00.003+01:00

Tonight is really good on 80m.

G6AVK is showing nicely on the TVEPG :

Lovely signal, peaking over 30dB S/N, I think it is the best I have had here with my little portable setup.

News about the grabber script

2009-12-20T13:33:00.004+01:00

The script was running smoothly until some time yesterday when it just seemed to stop (freeze).

I suspected the number of files in the backup directory and moved them away, and the script runs again. It looks like the script will have to be able to move the files, eg. to directories per date, or alternatively avoid saving the files when running unattended for extended periods.

I am conferring with Allan (the script author), but I could at least change the moving of the file in the script to a deletion.

Otherwise the script has been running very nicely, I am quite happy with it.

600m test for the TVEPG

2009-12-18T15:29:00.005+01:00

I tried this afternoon, the first identifiable Amateur radio signal comes from DI2AM, a museum ship in Rostock. The signal has a nice S/N of about 20dB, and given the distance of somewhere between 150 and 200km it is not very surprising to receive it.

Not bad for a very portable setup : EeePC, Sony SW-100 RX and a wire of about 20m length.

Update :

Just tested with the built-in ferrite antenna of the RX : The signal is now just visible and barely readable. The wire antenna does its work. Back to the wire antenna.

The Very Experimental Portable Grabber has been om 600m.

Tests with frame antennas and external ferrite antennas could become interesting.

The Portable QRSS Grabber runs on Linux now

2009-12-15T21:42:00.005+01:00

I visited a friend having done a script for uploading grabber images today. We tweaked the script to my server etc and it is now running.

The portable grabber uses a Sony SW-100 receiver capable of setting the frequency with 100 Hz steps. this means that the maximum frequency error should be contained within 50 Hz

In the first tests, the frequency was not properly calibrated, so nothing at all was seen.

The grabber software runs on a EeePC 1000H, and was running the grabber the past few days in Windows XP .

The whole setup with Linux, (the distribution JoliCloud is used here), installing JoliCloud, WINE and SpectumLab took a few hours from a purely XP machine to a running grabber.

Back home I extended the antenna - well, added a lenth of wire outdoors, extending the indoor part with a part away from the PC, and voila, G6AVK's signal appeared.

I hereby declare The Very Experimental Portable Grabber (TVEPG) a success.

Portable Grabber Setup

2009-12-13T21:47:00.008+01:00

Experimenting with a portable setup for a grabber I am trying out the following :

A Sony SW-100 portable receiver (top) with SSB with a piece of extra wire connected to the telescopic antenna, using a EeePC with SpectrumLab running under Windows XP, upload software is ArgoUpload.

At the moment looking at 3599.850 - 3600.050 kHz for QRSS signals.

Grabber changed to other capture machine

2009-12-09T21:47:00.002+01:00

The experiment with running Spectrum Lab in a Virtual Machine under Mac OS did not look so good. There seems to be some small frequency shifts, even on a fully static carrier.

The Grabber has been moved to a Windows machine I had anyway. I will probably add WSPR later, but it is getting late, so stopping activities for today. The activities with the Chinese "active loop" took up some time today, so this is it.

The grabber already looks better.

Non ? Active loop antennas

2009-12-09T19:03:00.005+01:00

I found some Chinese "active loop antennas" on eBay the other day, the price
was reasonable at $25, so I decided that it was worth the risk trying it out.

Since it had the brand name "Degen" (type "31MS" - guess that would mean MW and SW) Joachim and I joked about it being a "degenerative" antenna.

I picked the antenna up at the post office today, and gave it a brief try, and it looks like it lives up to its name and that the joke was not really a joke at all.

The first thing that happened was that a suction cup for mounting the antenna on a window would not stick to any window at all, poor manufacture quality, even for a Chinese product. It did not bode well.

On MW the S/N is lower on the Degen than on the built-in ferrite antenna. on a part of shortwave it looks like it has some minor gain on frequencies in the 5 - 15 MHz range, but its effectiveness was not easily detectable.

I may have to try it during daytime, but I am not optimistic.

If you see it for sale, it does NOT have my recommendation. I may be able to use parts of it for experiments, but I doubt it will do much for me.

In any case I intend to take it apart and see how they managed to do so little.

Conclusion : Cheap antenna with cheap performance.

FAIL.

Grabber mostly on 30m

2009-12-08T15:42:00.002+01:00

When no experiments on other bands are going on, the experimental grabber will be on 10 MHz for now

I did not check the images, but I suspect nothing came form the 160m experiment yesterday evening.

Experimental grabber moves around a bit

2009-12-07T21:17:00.002+01:00

Tonight I will be on 160m, "listening" for G6AVK and who else might be visible.

Grabber URL

It will move around a bit - hence the "experimental".

Experimental QRSS Grabber online

2009-12-06T20:03:00.005+01:00

I had some trouble getting Linux running on a newer machine here, so decided to test out my Mac and Win XP running in a VM under Parallels.

Using the FT-817 with a 30m loop antenna, the Grabber is set to monitor the low band QRSS frequency on 40m, 7000.780 - 7000.920 kHz

The software is Spectrum Lab in conjunction with ArgoUpload

The Grabber can be found here , subject to change, updates and possibly extensions to more bands.

Linux QRSS grabber on the way

2009-12-05T18:10:00.002+01:00

I just received a bash script for Linux from OZ5AR.

This script looks at the directory where Spectrum Lab puts its capture files, looks if a new file has been saved by SL and uploads it to the website.

The script need a bit of adapting to my needs, but should be tested this week end.

QRSS on 80m

2009-12-03T11:52:00.011+01:00

On Monday evening I was watching out for Colin (G6AVK) on 3559.9 kHz

He was transmitting QRSS3 with about 1W out, and propagation was rather poor. but at 2100Z the signal popped up :

... and stayed for about 20 minutes before fading out :

I am using a FT-817 with a 30m circumference loop antenna strung above the rooftop of the apartment building, and fed inside the apartment with 450 ohm air spaced ladder line and a good balanced tuner.

RFI hunting.

2009-09-19T16:14:00.004+02:00

I have been doing some RFI hunting today, in order to find some of the noisy switch-mode power supplies in the appartment.

I found a rather noisy one (cheap "universal" laptop supply) with wideband "carriers" every 70 kHz and the noise level dropped considerably when that one was disconnected.

I have been considering replacing as many as possible of the switch-mode PS's with linear regulated ones, because it is far too noisy here, Maybe not worth it, since some neighbours probably have some noisy ones as well.

In any case I am enjoying the little bit more quiet environment here.

It is far from over yet, but a good beginning.

New toy : HF3

2009-09-07T16:40:00.003+02:00

I could not resist any more, so got me a new LF/MF/HF receiver, the Target HF3 covering 30kHz - 30MHz

It will take a while to get used to the frequency settings, though I can see why it is made like that.

Otherwise the receiver is simple enough to operate, I used the same method of QRSS calibration as I did for the SW-1, so now it is test receiving the 30m QRSS band.

Just had the 50Hz sidebands in here, stopped a few minutes ago, presumable an OTH radar system.

Mini QRSS system

2009-09-06T22:21:00.005+02:00

I am back from a visit to Denmark, and found a nice little setup for watching QRSS.

I was using the Eee 1000H - running SpectrumLab - with a Sony SW-1 receiver (and an audio cable)

Everything can be run from a battery, so no problems with hum.

The SW-1 has AM and SSB reception from 150kHz to 30MHz with 1 kHz steps, so by calibrating with the Russian RWM time signal transmitter I could find the QRSS band on 30m. The SW-1 needs a bit more antenna than the built-in telescopic whip, so a wire antenna was attached to the whip. The SW-1 does have an input jack for an (active) antenna, so that will be tested later. Probably a small tuned loop antenna.

I was not using it a lot, so very few signals were heard. The concept worked well enough, and the frequency drift was not excessive. I set the bandwidth of the "grabber" to 200 Hz, though.

Nice and easy low power portable receiver setup, I may use it at home as well, with external power supply.

Update :

Next step ? : maybe using the Asus Eee4G with linux/WINE, running SpectrumLab - it could hardly get any smaller.

Further, a simple DC-RX - maybe powered by the USB port ?

Too close for comfort - poof !

2009-07-22T20:10:00.003+02:00

Looks like I blew my sband LNA.

I noticed that I could not hear the "beacon" sat signal on 2242.488, so checked. changed the LNA to another one, and signals came back - probably with a slightly higher Noise Figure (L-band LNA).

so - I opened the LNA and what did I find ? it is not a GaAs Fet amplifier as such, but a GaAs MMIC. Not really a problem, I have a replacement with the same pinout - only snag - it is SMD, so I hope my soldering and vision will up to the challenge.

LNA Spiritus Basta !

Why did this happen ? I transmitted on 2m with an antenna too close to the sband antenna. Oops !

half hour antenna for satellite reception

2009-07-21T14:54:00.005+02:00

I was growing tired of having poor reception of the transmissions from ISS on 145.800/825 and 143.625 MHz, so decided for a quick ground plane antenna. What to do for a quick antenna ?

Here we go :

1) use a piece of coax, strip about 53 cm of the shield off
2) connect 2 pieces of (insulated) wire about the same length to the shield connection
3) insulate with duct tape for a quick weather protection (will not hold long, but this is a temporary setup)
4) string the thing up between the clothesline and the balcony railing
5) pull the cable through the wall/door/window
6) add connector indoors to the radio and connect to radio
7) done

Results receiving ISS were better than using mu uhf-satcom log periodic array (no real surprise there)

I still need a better antenna/antenna position (poor reception when the ISS signal has to go through the buildin), and since I have some noise, so more to do.

Probably a 2m antenna with preamp (cable length) in the dormer.

A bit of slow progress for S-band

2009-07-18T14:41:00.002+02:00

In order to test the filter I got via ebay, I just connected it outdoors, not really the best thing to do.

Today I went to the local "elektronica-boer" and got some connector adapters making it possible to move the filter indoors. I had to retain the filter before the extra indoor amplifier in order to avoid IMD problems, so a bit of extra adapters were necessary.

One day I will have to make a web page describing the whole thing, but that is for later.

Busy day tomorrow with non-radio stuff, so hope to get a bit more done today.

Another alternative for S-Band

2009-07-17T21:11:00.004+02:00

I just found yet another alternative for "watching" satellites on S-band.

I have an Icom R3 receiver, covering up to 2.5 GHz, albeit only for FM and ATV. However, I found a rather simple modification for an IF output at the site of G6LVB where he describes the mod.

I think I will do that one and see how it works, even before I start modifying the converter. Only problem seems to be frequency stability.

The IF in question is 26.05 MHZ, but I have one of the Elektor programmable SDR's covering up to 30 MHz, so that looks like a useable, if not ideal solution.

This could, of course also be used with a HF receiver for receiving SSB or CW on the 13 cm amateur band

So many ideas, so little time.

MMDS converters have arrived

2009-07-16T21:19:00.003+02:00

About two weeks ago I decided that my setup for S-band reception needed to be upgraded seriously.

So I looked into possibilities for improvements. I found the filters necessary for the AR8200 receiver to work, and looked around to see if I could find some converters that were (relatively) easily modifiable.

I think I found it . MMDS converters cover the bands around 2150 MHz and around 2600 MHz, and it should be possible to modify the filters

TranSystem Inc makes some MMDS converters, I found some on ebay, TranSystem Model EIDC 3033 Down Converter, apparently with the following spec :

RF bands :
2150 - 2162 MHz and
2500 - 2682 MHz,
Intermediate frequencies :
116 - 128 MHz and
222 - 408 MHz

This is possible with a LO frequency of 2278 MHz. Since I want to use the converter for the 2200 - 2300 MHz band, some modifications are necessary :

RF filters - one pair at the input and one pair between the RF amplifier and the mixer - must be modified to cover 2200 - 2300 MHz

The Local Oscillator (LO) needs to be moved away from the wanted passband, preferably for a low side LO.

I took a look at the inner workings of the converter, and the RF frequency filters are stripline filters made of copper with air insulation (not microstrip etched on the PCB), so they are expected to be fairly high Q filters. For satellite S-band I think the best strategy will be to shorten the 2150 MHz strips (careful - we do not want to get too high in frequency), then disconnect the higher frequency filter (hmmm - that may not even be necessary).

The other modification concerns moving the LO down. The LO is a PLL with a frequency divider (256x) 2278MHz down to 8.898438 MHz. (Xtal in the reference oscillator).

It would be nice to have the oscillator running on a "rounded" frequency like 2000 or 2100 MHz, but that would require new Xtals to be made. Since I would like to be able to lock the LO frequency to a stable source that complicates things.

The other option will be to use a 8 MHz crystal oscillator, then lock that to a 10MHz TCXO or other standard. This will provide the converter with a LO frequency of 2048MHz. not exactly very "rounded", but still with a full MHZ, so the readout of the converted frequency should not be all too confusing (that remains to be seen). After all, a computer can do wonders in calculating the correct frequencies and control the receiver(s).

Time is a bit tight this week end, but I hope to be looking into it after all.

LRO without GSM

2009-07-15T11:43:00.002+02:00

This morning I woke up early and saw the moon was out. Tested the reception of the LRO, and it was not loud but clearly there, even audible in the speaker, more details later.

GSM interference not quite gone .... well - it was, really

2009-07-11T18:05:00.005+02:00

It looks like I spoke too soon.

The interference from the GSM has re-appeared, tough not as strong as it was. After setting up some 260MHz antenna and preamp again, it came back. I may have to use a different preamplifier (tuned) for that system.

More work to do ....

*****Update : It was *not* the dreaded return of the GSM interference ....

Apparently , by adding the second amplifier (and a second receiver) in the system, I inadvertently made a loop creating humm in the system.

with less "MIC boost" at the pc sound card input the problem disappeared (only the base 50Hz and the 3rd overtone 150 Hz are visible on the spectrogram now), and I am now back to a quiet S-Band reception.

Phew !

S-Band filters have arrived

2009-07-11T14:41:00.004+02:00

I picked up the S-band filters on the post office today, and it turns out that there are indeed two different filters

1) Centre frequency 2125 MHz, Bandwidth 295 MHz (I assume 3 dB B/W)
2) Centre frequency 2375 MHz, Bandwidth 295 MHz

I tried both filters and it looks like the lower freqeuncy filter does not - to a sufficient amount - attenuate the unwanted signals, so I will use the second one .

The GSM sidebands have completely disappeared, much to my relief. (Not a trace of them in the spectrogram). I need a bit more amplification, but that is easily arranged using a second satellite TV in/line amplifier.

It looks like my theory of insufficient image rejection in the receiver is correct.

Now for some S-Band satellite signal hunting - and of course the LRO on S-Band.

S-Band Filters

2009-07-06T19:04:00.003+02:00

I found someone selling some filters on eBay. The description said centre frequency 2125MHz and bandwidth 295MHz

However, when looking at the photo it looks like there are two different filters :
2125/295MHz and
2375/295MHz.

If that is correct I will have two very useful filtersone covering approx 1975 - 2275MHz (useable for most of the satellite S-band downlinks (2200 - 2300MHZ), and one covering 2225 - 2525MHz also useable for a good part of the Satellite S-Band downlink band , as well as the Amateur radio *and ISM) band from 2320 - 2450MHz.

Both filters are indeed usable for reception of the LRO on 2271.200MHz

If the two filters in the photo are indeed what I will receive.

When I receive the filters, I will be able to test whether my theory of poor image rejection in the receiver is correct, or if the problem is caused by IMD outside my RX system.

In any case this is going to be interesting.

Lunar Reconnaissance Orbiter

2009-07-02T13:39:00.004+02:00

The last week or two I have made an attempt to receive signals from the Lunar Reconnaissance Orbiter (LRO).

The LRO is currently in a polar orbit about 50km above the surface of the Moon, and has a transmitter on 2271.200MHz. It is possible to receive on Earth, as several people have done, already in it early days.

I decided to see if I could do this using "off the shelf" equipment with the antenna on a balcony.

I started my efforts using a handheld scanner , the AOR 8200 Mk3 which covers this frequency in SSB mode. Since I know that the sensitivity is insufficient on that frequency I started out using a LNA2227 (LNA), having a Noise Figure of less than 1.5 dB and finally a logarithmic-Periodic antenna (LPDA). no luck, but got a grid of "carriers" spaced about 215 Hz .... hmmm ... sounds like GSM.

After a few days I found myself digging out a WiFi grid dish with linear polarisation. still no results, and still GSM carriers.

Testing if this was Intermodulation Distortion (IMD) in my receiving system was done with a 10 dB attenuator ... the interference duly reduced by 10 dB, eliminating the suspicion of IMD in my system. I suspect two possibilities : Either IMD created somewhere outside my RX system or poor Image Rejection of the receiver. Most likely is the Image Rejection problem, since the GSM sidebands are strongest in the direction of a nearby base station.

Testing the connection between LNA and receiver revealed that the LNA had insufficient gain to overcome the high noise figure of the receiver, so what to do now ?

A quick test was set up using a satellite TV in-line amplifier, powered by a satellite receiver (off-the-shelf, remember). Still no success, but the noise performance was clearly better, as witnessed by other satellite signals in the 2.2 GHz band. Well, the moon was hidden by a tree at the moment of testing, making it difficult to point the antenna in the right direction. Still no signal from the LRO. I was beginning to doubt the usability of my system, but not yet giving up.

Finally, yesterday evening, the Moon was clearly visible, the antenna was pointed to the Moon, and bingo .... there was the signal ! A slanting line on the spectrogram showing a downwards change in Doppler shift.

Preliminary image 1 : http://www.xs4all.nl/~jgander/LRO1.jpg

I followed the signal till the LRO disappeared berhind the Moon, with the Doppler change getting much lower.

Preliminary image 2 : http://www.xs4all.nl/~jgander/LRO-gone.jpg

So - after a week of experimentation, finally success.

The receiving system need much more work, the first test will be making a filter that should (ideally) get rid of the GSM interference.

Acer Aspire One as QRSS grabber ?

2009-06-13T22:27:00.003+02:00

Today I installed the Ubuntu version made for netbooks - the "Easy-Peasy" distro - on my Acer Aspire One.

The install rendered the Wireless LAN inoperable, but after a standard update (via the wired LAN) it was working fine.

After installing a few of my well known applications I tried to get SpectrumLab up and running under WINE.

After an attempt to install on the "Z" drive failing, I finally got it installed to the "drive_c"

It took a bit of playing around with the mixer to get the input from the radio running. Apparently the sensitivity of the AA1 mic input is somewhat lower than on an older machine I have working here.

After some hours of work with the AA1 I intend to leave it for now and continue my reading. Later for trying to get WSPR/WSJT running - that should be "fun" (yeah - right!).

With SpecLab I should be able to make some simple grabber software for image upload, possibly with a script. I will need more knowledge of Linux than I have now, but this is part of getting things working.

80m SDR, p3

2009-06-09T22:03:00.002+02:00

Finished the PCB (except the canned oscillator), needs testing , but later. the box needs one more hole for external LO connector - not originally provided for.

Finished second novel of the marathon reading, now 3 mopre novels, some novelettes and novellas until July 3rd. Let's see what can be done.

80m SDR, p2

2009-06-03T20:33:00.002+02:00

More solder smoke released, only missing the ICs and the oscillator - I am going to leave out the oscillator and make a local oscillator input, making a switchable Local oscillator possible.

Now for some more reading.

Building SDR for 80m

2009-06-02T21:13:00.004+02:00

Today I received the kit from the magazine "Funkamateur" with all necessary parts to build a "single frequency SDR", similar to the SoftRock, along with a few other components for my constructions.

Like for Joachim, one resistor had a 1000 times larger value than the one needed. No problem, since I had one of the correct value.

Some solder smoke generated, not quite finished yet, but it is time for some reading.

Spotted on 10m

2009-06-01T22:37:00.002+02:00

Twice today I spotted IZ1ERR on 28 MHz, and now I see he spotted me, too :

Spot Database

Specify query parameters

Timestamp Call MHz SNR Drift Grid Pwr Reporter RGrid km az
2009-06-01 17:14 PA9QV 28.126170 -22 -4 JO22db 0.2 IZ1ERR JN35 758 164

Nice to see someone else is there. Now let us get some activity on 28 MHz WSPR before the Sporadic E season is over

Wspr on 10m

2009-06-01T15:49:00.002+02:00

I am currently running the WSPR station on 10m, Dial setting : 28.124600MHz, also looking for QRSS signals on 28.125900 to 28.126000MHz.

Using a FT-817 running 10% tx-ing when I am home, otherwise just rx-ing.

I have only had a single spot today from IZ1ERR in JN35, so I guess activity is quite low atm.

I am looking forward to the peak(s) of the sporadic E season.

FT-817 PA

2009-06-01T13:54:00.003+02:00

The FT-817 PA seems to be prone to overheating.

I have been running the 817 on 13.8V till now, and since it runs fine down to about 9V, I am thinking of finding a 10V regulator to take some heat out of the equation.

Will be looking for a 7810 IC, or possibly using the LM317 for that purpose.

More soldersmoke coming out some time here.

Back to some radio stuff

2009-05-31T20:15:00.002+02:00

I have been away for about a week and I am back from the holidays. My spare FT-817is now here and will be set up for WSPR/QRSS and other experiments, while soldering.

I know there is some stuff waiting for me, eg. a "single frequency oscillator" SDR kit like the softrock design, that I will solder as soon as it is here.

I do have quite a bit to read in the next month, so the radio activity will be somewhat limited. I will have to solder a bit between th words ;)

FT-817 PA failure

2009-05-19T22:09:00.004+02:00

Looks like the PA of my FT-817 gave up the ghost. Maximum 50 - 100mW out of the transceiver, whatever I do.

It looked for a day or two like my WSPR signals on 10MHz were soewhat down, and quite right, minimalist output there.

I have decided to leave it as is for now, a bit of output is still there, but a repair has to be done at a later stage.

Also, I decided to move the FT-817 *as it is now, on 10 meters, so listening and *really* WSPRing on 28.126120 MHz if anyone pops up there I will be leaving the reporter on and with an estimated output power of 50mW, running concurrently with SpectrumLab for QRSS on 28.125900 - 28.126000 MHz, running with a full wave 10m loop inside my balcony, tuneable from 10 - 20m with reasonable efficiency.

First test 10 MHz RX

2009-05-17T21:22:00.004+02:00

looks like the AF amplifier is fine now, using abt 3 mA at 12V, Xtal oscillator uses abt 5 mA at 5V. Quite a bit lower power than the FT-817.

Having only one power supply in the shack for experimantation, I need to find a 78(L)05 in my pile of components, so I can test the XO and mixer. I wonder if the output of the XO is sufficient to drive the relatively low impedance (abt 2kohm) of the mixer. but guess it will.

No more soldersmoke for today. maybe a bit of reading for now.

WSPRing away

2009-05-17T14:12:00.004+02:00

As an intermediate solution I have set up my FT-817 for running WSPR on 10.140MHz - with 200mW out. The receiver does QRSS reception, too, but of course blacks out while WSPR is transmitted.

I made myself an interface similar to the VK2ZAY one, and it works nicely. The AF level out of the computer is a bit low for operation of the "VOX" circuit, and should be modified a bit, but otherwise it works fine.

Now, it is a bit of overkill to use the FT-817 for just 200Hz of the spectrum, after all it covers all bands from 160m to 70cm. So the 10MHz direct conversion receiver of the previous post is just the beginning, a "proof of the concept", used for WSPR transmission and reception and QRSS reception

The intention is to build, at a later stage, a full, but simple, "single frequency ssb direct conversion transceiver" and a dedicated 30m antenna tuned to 10.140 - probably a "magnetic loop".

For now I have a fairly large reading project, so the ful TRX will have to wait a bit.

10MHz qrss rx

2009-05-17T01:05:00.003+02:00

I left the 10m TX for a while and got started building a simple 30m direct conversion QRSS reveiver.

Discussions with Joachim resulted in two receivers one already built by Joachim and the one I am building now, with a local oscillator at half the RX frequency and using a RA3AAE type mixer

For this RX I am generally following this concept found at PA2OHH, the difference is that I - like Joachim - use a canned oscillator at 5.0688 MHz

The Oscillator/mixer and the AF circuit is ready for an initial test (tomorrow), and the RF input circuit is yet missing.

QRSS transmitter under construction

2009-05-12T20:12:00.000+02:00

In talks with Joachim, PA1GSJ we decided to build the simplest possible (construction wise) transmitter for 28MHz.

Using a "canned" - in my case IC-like housing - oscillator on 28.322 MHz and a 74HC(T)240 as the "power amplifier" it is possible to get an output of around 50 mW, sufficient for a QRSS MEPT.

Joachim already has his model working, and I am in the process of building mine. The oscillator is there (duh)and the "PA" is just about wired, now I need to make the keyer , will be using a PICAXE processor, and the output matching circuit/low pass filter.

PA9QV on Ham radio

2009-05-11T14:53:00.000+02:00

This will deal with my Amateur (HAM) Radio activities, newly started with a bit of QRSS and WSPR activities, more later.