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From: "Dave Sergeant" <dave@davesergeant.com>
To: rsgb_lf_group@blacksheep.org
Date: Tue, 17 Jul 2007 20:41:06 +0100
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Subject: Re: LF: Re: RE: LF 500khz
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On 17 Jul 2007 at 19:51, Vic@VicsFloridaVilla wrote:
> 
> I would ceratinly appreciate a scan of your tx design . That would
> give me a good start. My design skills are rather limited - my only rf
> qualification is the RAE which I tookin 1978 but I love tinkering and
> homebrew. Having built a K2 and recently a KX1 I have gained a lot of
> confidence to have  a crack at a 500khz rig. So far the transverter
> looks very promising. 

If you have not found it already, you might also be interested in my 
transmitter - see http://www.davesergeant.com/mf/
 
> Having followed the postings on the reflector I agree a pre selector
> on rx looks essential and I think a resonant antenna. But some
> stations seem to get quite good results with fairly modest antennas so
> there is hope !

I along with a few others use the Datong UC/1 upconverter (feeding my 
K2) and get excellent results. Good sensitivity and no problems 
whatsoever from MW crossmod. The UC/1 has a fairly sharp preselector 
at its front end so guess that helps.
 
> My progress on 500 will be slow due to other comittments but I am
> determined to put out a signal on that band !
> 

I guess the 1 year experiment will be over before some of us really 
get going on the band. I seem to be going one step forward and one 
step backwards at the moment. This afternoon I took the opportunity 
between the showers to establish the impedance of my vertical at its 
base - Gould sig generator on a long extension lead in the garden. 
Using G3LDO's 3-meter impedance tester I carefully adjusted the 
tuning inductor and matching ferrite transformer to get a nice 50ohm 
resistive impedance at the antenna base. Went back in to the shack 
and found a diabolical swr there..... Maybe I have some very strange 
coax if 50 ohms at one end produces silly impedance at the other....

73 Dave G3YMC

http://www.davesergeant.com