"Progress" report 500kHz RX antenna

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.

600m test for the TVEPG

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

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

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.

Non ? Active loop antennas

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.

Mini QRSS system

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 ?