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Date: Fri, 18 May 2007 22:15:18 +0100
To: rsgb_lf_group@blacksheep.org
From: Alan Ibbetson <alan@g3xaq.demon.co.uk>
References: <ySM$64Ar6gTGFw98@g3xaq.demon.co.uk>
 <008001c7998e$b3f608c0$34556a58@wgt01>
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Subject: Re: LF: Re: G3XAQ on 502.0 KHz
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Hello Gary,

When you say "see anything", do you mean you are expecting me to be 
using a computer based transmission? I'm actually using ordinary morse, 
currently at about 12 wpm. I wonder if you can "hear" me? I got a 569 
SWL report from G3XVL in Ipswich, so I seem to be getting out OK.

Best wishes,

Alan

In message <008001c7998e$b3f608c0$34556a58@wgt01>, Gary - G4WGT 
<g4wgt@tiscali.co.uk> writes
>Congratulations Alan,
>
>I can't see anything of you up here in Lancashire but there is a signal 
>keeps showing on Dave's (G3YXM) 500 KHz grabber on 502.000 KHz, could 
>it be you ?
>
>Go to :-
>
>http://www.wireless.org.uk/grab/
>
>73
>
>Gary - G4WGT - IO83qp
>
>http://myweb.tiscali.co.uk/wgtaylor/
>Web site updated 07/05/2007
>
>
>----- Original Message ----- From: "Alan Ibbetson" 
><alan@g3xaq.demon.co.uk>
>To: <rsgb_lf_group@blacksheep.org>
>Sent: Friday, May 18, 2007 9:38 PM
>Subject: LF: G3XAQ on 502.0 KHz
>
>
>>I have today got my 500KHz station on the air. I am located near 
>>Canterbury, locator JO01md. Here are some technical details.
>>
>> The aerial is an inverted-L with a 15m vertical and a 35m horizontal 
>>section. This was originally my top band aerial. I have added a 1mH 
>>end loading coil (460 turns of 0.5mm enamelled wire on a 38mm OD white 
>>poly  waste pipe occupying 275mm of winding length). The loading coil 
>>is 14.7m  from the far end. I trimmed the 14.7m for resonance at 
>>502KHz because I  wanted a roughly resonant aerial to simplfy feeding, 
>>but from the way the  resonance wanders about as the wind blows I'm 
>>not convinced this was such  a great idea. Standard formulae suggest 
>>this aerial has a radiation  resistance of almost exactly 1 ohm.
>>
>> The aerial is end fed against a reasonable earth system comprising a 
>>20m x  20m mat of stock fencing with the sections crimped together. I 
>>also have  about twenty 30m radials. On top band I can work east coast 
>>US easily with  100W and I have worked VK and W6 with 400W. I was 
>>quite surprised (well,  p****d off) to measure the return loss of the 
>>aerial system at 502KHz as  22dB. This suggests the input resistance 
>>is a little over 40 ohms, almost  all of which is earth loss 
>>resistance! So much for my "killer" top band  earth mat.
>>
>> I am using a link-coupled series tuned ATU with a loaded Q of 7 
>>placed at  the base of the aerial to get the SWR very close to 1:1. 
>>The 2:1 SWR  bandwidth of the aerial system is less than 2 KHz (1KHz 
>>either side of  resonance).
>>
>> I have built a QRP transmitter using an ECL82 triode pentode, as 
>>popularised by G0UPL and others. Output is 4 watts. Cathode keying 
>>with a  small choke and 0.5uF capacitor gives a clean 3msec rise and 
>>fall on the  keying waveform, but the un-neutralised PA has a backwave 
>>that is only  40dB down. I've added a "half wave" filter after the pi 
>>tank in an effort  to avoid QRMing MW broadcast stations. Harmonics 
>>are over 50dB down.
>>
>> The main HF station FT1000MP Mk5 seems just OK on 500KHz. Band noise 
>>is S  1 in a 500Hz passband on the meter.
>>
>> The rig is crystal controlled on 502.0KHz, so you know where to find 
>>me!  All I need now is some stations to work. "Can you hear me, 
>>Mother?".
>> --
>> Cheers,
>>
>> Alan G3XAQ
>> alan@g3xaq.demon.co.uk
>>
>>
>>
>
>
>

-- 

Cheers,

Alan G3XAQ
alan@g3xaq.demon.co.uk