The change from 500KHz to 472KHz rendered a few mini Xtal controlled TX modules once used on 500 redundant so I have changed them to DDS control.
I have run the 200uW TX again which gave me my first spot on 500kHz in 20009 :-
2009-11-22 00:48 G3ZJO 0.503814 -30 0 IO92ng +17 0.050 M0BMU IO91vr 76 47
Since that first report I have made antenna improvements so assuming no changes at M0BMU these should be reflected in the report from that rig.
2013-01-28 00:50 G3ZJO 0.475790 -18 0 IO92ng +0 0.001 M0BMU IO91vr 76 47
Last night I ran a different mixer/driver to the same PA still 200uW EIRP with very much the same results.
2013-01-30 00:30 G3ZJO 0.475612 -21 0 IO92ng +0 0.001 M0BMU IO91vr 76 47
Today I completed the change of my very first test TX into a buffer, this TX could never produce enough signal into my first antenna experiments for a decode. I measured the power into a 50R load it is 10dB down on the above TX so 20uW EIRP. I tried it as the PA.
Smaller than the average MF PA this postage stamp size device produced predictable results. Low component count, the SMD chip is under the Veroboard, the LPF is in line to the antenna.
2013-01-31 14:46 G3ZJO 0.475601 -30 0 IO92ng +0 0.001 M0BMU IO91vr 76 47
After 4 transmissions (only 8 minutes on air) my best DX is 100Km.
2013-01-31 14:56 G3ZJO 0.475602 -29 0 IO92ng +0 0.001 G3SZS IO81vv 100 62
If I was calling CQ on the key I estimate 8000 Years before I got any report AT ALL.
Unfortunately the power levels shown by the WSPR reports are not correct and must be disregarded.
As a follow up to my earlier post. PREVIOUS POST
Jim G3KAF contacted me as have (several others over the years) about a problem he had with this well loved PSU. Jim had a voltage regulation problem. The Voltage dropped when current increased.
Jim like me would have liked a circuit diagram for the PSU, he managed to identify the value of a capacitor from my photograph. The fault remained though, only a few days later he found the problem.
On the small board with all the components the diode which rectifies the low voltage ac supply (next to the 470uF 12v capacitor) was highly suspect because the 470uF was getting warm!. When I took the diode out and checked it, I found it was a dead short circuit. Having replaced it the PSU is now working superbly well. I had changed all the 8 smoothing capacitors and the bridge rectifier and now I can go from zero amps to 20 amps and the voltage only drops 10mV (0.01 of a volt). I suspect it has not performed this well for years.
Thanks Jim for the information, if anyone has a circuit diagram or other information / faults found, please contact me.
My VLF Grabber has been hosted by bplaced.net for some time. The hosting is fine but does require that you log into the forum often (at least every 2 months). Golly 2 months goes quickly these days, once again my site has been suspended. I don’t need this, I want a reliable site that is there for all to view as and when.
Time to move VLF to join my other Grabbers, actually it has been there for some time but now we need to make it the default.
G3ZJO VLF and Sub9KHz Grabber
G3ZJO VHF and Meteor Grabber
G3ZJO LF and MF Grabber
Easy I don’t know why I didn’t do it in the first place, for some reason I wanted to host it separately. If I add more they will join these finding them couldn’t be easier /vlfgrabber, /vhfgrabber /lfgrabber so an hf one would be /hfgrabber. All right I admit it, it could be easier, how did I get one of them as .htm and two as .html, proof of being humnan I suppose.
I wanted BAV21 diodes for my 50 Ohm loads. They are cheap but getting them is not easy, some suppliers want to add as much as £7.50 packing and delivery charge. I had a free carriage order to go to CPC and I could have added them, however they sold the diodes in 10’s for 21p, they had only 6 in stock so I couldn’t have them. Will those 6 diodes ever get sold.
I have had them in stock for a while now but Treacle consumption went down at the ZJO house, technical problems are always getting in the way.
Today I washed out my Special Edition, Trick Or Treat Treacle tin and drilled the holes, fitted the more conventional 20 X 1K 3 Watt resistors load, filled the tin with the remains of my Baby Oil and there we have it.
I have also changed the 2 x 1N4148 diodes used in the smaller load so that the Forward Voltage is 0.64 for both.
2013-01-06 22:48 G3ZJO 0.475699 -26 0 IO92ng 0.005 OH1LSQ KP03td 1785 39
1785Km is my personal best distance nearly up to 2000Km, that doesn’t seem impossible now. My tiny 6m x 6m Inverted L antenna produces around 5mW EIRP from the home brew transveter.
For me there is so much fun to be had with QRP. I have HF 100W rigs, I have never run them at 100W, likewise VHF/UHF even if the rig is capable of 25W I rarely use more than 5W for Meteor Scatter contacts on 6m I use 15Watts only. I just love to use my 4W PEP SSB converted multimode CB rig on 10m and get through the pile ups.
That is just me and there is room for all sorts in this world.
I had a new Ford Focus on loan some years ago when insurance repairs were being done to my car. Several work colleagues asked, “what does it do”, “no idea”, “well how fast have you been”, “almost 60MPH on the urban dual carriage ways coming to work, 60 is the speed limit on those”.
It was 13:00 before I reassembled my loading coil set up after adding in the extra turns which I wound on many months ago when the 472KHz band was first announced. It was so long ago in fact that I didn’t remember whether I had got to use all the new turns or one of the taps on each new turn. I went for the top turn and it was right, I know I calculated it at the time.
The first 6 hours results are looking good both for TX and RX. Daytime DX of 1065 Km to DL4RAJ in JN68kj is good going.
The receive results are good too the band is much clearer of Plasma TV interference. I am ignoring the false looking decode from QR somewhere down in the south Atlantic.
There was a good turnout for the final hours of 500KHz operation yesterday.
I counted down the hours left on WSPR from mid day and sent my last at 23:58 UTC
Countdown xxxxxxx Hours to go x
2012-12-31 11:38 x G3ZJO/12 x 0.501510 -20 0 IO92ng +7 0.005 G8HUH IO81mg 181
2012-12-31 12:36 x G3ZJO/11 x 0.501510 -11 0 IO92ng +7 0.005 G3WCB IO91rm 86
2012-12-31 13:56 x G3ZJO/10 x 0.501513 -18 0 IO92ng +7 0.005 G0KTN IO81ti 145
2012-12-31 14:44 x G3ZJO/9 x 0.501507 -18 1 IO92ng +7 0.005 G8ALS IO92fk 49
2012-12-31 15:48 x G3ZJO/8 x 0.501511 -21 1 IO92ng +7 0.005 M0DTS IO94il 247
2012-12-31 16:24 x G3ZJO/7 x 0.501508 -31 1 IO92ng +7 0.005 PA3ABK/50 JO21it 385
2012-12-31 17:14 x G3ZJO/6 x 0.501510 -11 1 IO92ng +7 0.005 G3WCB IO91rm 86
2012-12-31 18:34 x G3ZJO/5 x 0.501515 -25 1 IO92ng +7 0.005 GW0EZY IO82ho 173
2012-12-31 19:18 x G3ZJO/4 x 0.501510 +0 1 IO92ng +7 0.005 G3XIZ IO92ub 46
2012-12-31 20:10 x G3ZJO/3 x 0.501510 -24 1 IO92ng +7 0.005 DF0WD JO42fd 636
2012-12-31 21:02 x G3ZJO/2 x 0.501509 -28 1 IO92ng +7 0.005 G6AVK JO01ho 127
2012-12-31 22:10 x G3ZJO/1 x 0.501510 -17 1 IO92ng +7 0.005 G0KTN IO81ti 145
2012-12-31 23:58 x G3ZJO__ x 0.501513 -13 0 IO92ng +7 0.005 G3WCB IO91rm 86
GI stations were copied at good strength on CW and Opera transmissions were made.
Listen to the activity by downloading the Audio from these links.
AUDIO FILE 1
AUDIO FILE 2
AUDIO FILE 3
AUDIO FILE 4
AUDIO FILE 5
AUDIO FILE 6
And finally the last few dots and dashes
AUDIO FILE 7
And the band is left to the interference from Panasonic Plasma Televisions.
You can listen to the files using your Media Player or view using Spectrum Lab.