Date: Sun,  7 Sep 2003 23:15:06 +0200
From: "Marek Przybyszewski" <sq5bpm@wp.pl>
To: rsgb_lf_group@blacksheep.org
Message-ID: <3f5b9fda251e5@wp.pl>
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Organization: Poczta Wirtualnej Polski S.A. http://www.wp.pl/
Subject: LF: Re: LF tests from Poland
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Dear all,

First of all thank you for all the reports. It seems that the 
only place we were heard was at SM6PXJ. Christer has put some 
pictures of our signal on his webpage ( 
http://www.xpress.se/~adsl1522/capture/sp5zcc/index.html ). I am 
very happy because I started to doubt whether the 
TX+coil+antenna combination work at all. Especially because my 
friend in the centre of Warsaw didn't copy me at all (now I know 
that probably due to QRMs). SP2PZH was not transmitting this 
Saturday at all due to some unexpected work duties.

Now I know that 150W is not enough. This "low power" is due to a 
power transformer 12V/20A which I simply had and the whole TX 
has been built around it. With 2 pairs of IRFP450 FETs currents 
above 12A are impossible. At least in my configuration FETs 
start to dissipate a lot of heat + less voltage goes to the 
output transformer, thus further increasing of power is 
impossible (at 12A at least 2V out of 12V are left on FETs). 
This week I plan to build a new power supply, with voltage 
around 60-70V which will probably work much better.

I am sorry, this is my "first try" TX and it works even better 
than I thought. As for the QRG - I had two quartz crystals in 
my "parts box", one at 10.000MHz and the second at 11.350MHz (I 
use the frequency difference). The VXO starts to work unstable 
above 1.37MHz (10MHz quartz is working at 9.98MHz then), that's 
why we have set this unsusual frequency for sked. I am sorry if 
that caused some troubles. I will build the VXO once again, now 
better screened etc. 

The antenna here is a rebuilt 160m dipole ca. 15m heigh 
(two "arms" were shorted) and a wire has been put, not totally 
vertical, of a total length around 50m. Grounding is a normal HF 
grounding plus 20m of 3mm copper wire put 5cm deep into the 
ground. Receiver is FT-990 with a typical two-stage bandpass 
filter with a pre-amplifier on BF245 and an emitter follower.

That is our equipment for now. We hoped to make some QSOs with 
this and it almost happened today. Of course, for serious work 
something new will be built as soon as possible!

Again thanks to everyone for trying, all the best and CU on the 
air! The 136kHz chapter has just started in Poland! 

vy 73! de Marek SQ5BPM
SP5ZCC Scouts Radio Club
http://www.sp5zcc.waw.pl/


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