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Message-ID: <001d01c75f82$df054440$87318351@w4o8m9>
From: "James Moritz" <james.moritz@btopenworld.com>
To: <rsgb_lf_group@blacksheep.org>
References: <PAEFLMFGBDKKCONLMLBIAEMJCJAA.ganymede444@btopenworld.com>
Date: Tue, 6 Mar 2007 00:03:29 -0000
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Subject: LF: Re: 500 GI4DPE-M0BMU MF QSO
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Dear LF Group,

Pleased to work Finbar GI4DPE and Pete M0FMT in my first foray onto the =
500kHz band just now. The QSB on Finbar's signal was very fierce, going =
from 569 to inaudible and back over a minute or so. It is quite =
surprising how good the signal strength is - then again, the noise level =
is much lower than on 136kHz.

 I had a few problems getting the system working over the weekend - =
mostly to do with having nearly as much signal from Radio 5 on 909kHz =
coming down the feeder into the TX as was going the other way on =
503kHz... it seems the combination of antenna tuner, coax feeder and TX =
harmonic filter had an unwanted resonance close  to the 909kHz TX =
frequency, which is running 150kW about 500m away from me. Changing the =
position of the low-pass filter  to the tuner end of the feeder seems to =
have solved  the problem for now.=20

I am using a linear amplifier I built a while ago for experimental =
purposes, turned down to about 4W output (it actually uses some of the =
components, including the output MOSFETs, from my first LF TX from =
1999). The antenna tuner is similar  to my LF set-up, with loading coil, =
variometer and toroidal matching transformer, but with only around 300uH =
total inductance. The antenna is  the same wire I use for LF. For =
receive, I am using the RA1792 with a loop antenna and preamp.

Cheers, Jim Moritz
73 de M0BMU
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<DIV><FONT face=3DArial size=3D2>Dear LF Group,</FONT></DIV>
<DIV><FONT face=3DArial size=3D2></FONT>&nbsp;</DIV>
<DIV><FONT face=3DArial size=3D2>Pleased to work Finbar GI4DPE and Pete =
M0FMT in my=20
first foray onto the 500kHz band just now. The QSB on&nbsp;Finbar's =
signal=20
was&nbsp;very fierce, going from 569 to inaudible and back over a minute =
or=20
so.&nbsp;It is quite surprising how good the signal strength is - then =
again,=20
the noise level is much lower than on 136kHz.</FONT></DIV>
<DIV><FONT face=3DArial size=3D2></FONT>&nbsp;</DIV>
<DIV><FONT face=3DArial size=3D2>&nbsp;I had a few problems getting the =
system=20
working over the weekend - mostly to do with having nearly as much =
signal from=20
Radio 5 on 909kHz coming down the feeder into the TX as was going the =
other way=20
on 503kHz... it seems the combination of antenna tuner, coax feeder and =
TX=20
harmonic filter had an unwanted resonance close&nbsp; to the 909kHz TX=20
frequency, which is running 150kW about 500m away from me.&nbsp;Changing =

the&nbsp;position of the low-pass filter&nbsp; to the tuner end of the =
feeder=20
seems to have solved&nbsp; the problem for now.&nbsp;</FONT></DIV>
<DIV><FONT face=3DArial size=3D2></FONT>&nbsp;</DIV>
<DIV><FONT face=3DArial size=3D2>I am using a linear amplifier I built a =
while ago=20
for experimental purposes, turned down to about 4W output (it actually =
uses some=20
of the&nbsp;components, including the output MOSFETs,&nbsp;from my first =
LF TX=20
from 1999). The antenna tuner is similar&nbsp; to my LF set-up, with =
loading=20
coil, variometer and toroidal matching transformer, but with only around =
300uH=20
total inductance. The antenna is&nbsp; the same wire I use for LF. For =
receive,=20
I am using the RA1792 with a loop antenna and preamp.</FONT></DIV>
<DIV><FONT face=3DArial size=3D2></FONT>&nbsp;</DIV>
<DIV><FONT face=3DArial size=3D2>Cheers, Jim Moritz</FONT></DIV>
<DIV><FONT face=3DArial size=3D2>73 de M0BMU</FONT></DIV></BODY></HTML>

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