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Date: Tue, 3 Jul 2007 16:03:49 +0100 (BST)
From: John GM4SLV <gm4slv@sighthound.demon.co.uk>
To: rsgb_lf_group@blacksheep.org
Message-ID: <Pine.LNX.4.64.0707031529250.8263@lurcher.twatt.local>
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Subject: LF: 500 k/c Update from Shetland
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Status: O

Hello all,

After receiving some encouragement to get involved on 500k/c I've spent 
some time getting a rudimentary RX setup in place.

I now have an inv. L at 8m high with 10m top loading section which I've 
been able to tune via series cct formed by a 1.5mH L and 500pf variable 
capacitor.

Initial calculations showed an estimated ant capacitance of ~110pF and 
the behaviour of the tuning cct would seem to back up the calculations.

I hope to re-assemble it all again this evening and do some listening.

Over the weekend I heard G3XEV, along with the BHZ beacon, but there was 
a bit too much QRN being coupled via the connection to the PC soundcard 
to see down to the real noise floor using Spectrum Lab etc. 

With the RX disconnected from the PC the band was quiet enough, so I've 
just added audio isolating xfmrs to the lead between the AR7030 and PC - 
hopefully this will help (I'll only know when I get home from work). If 
it works this will allow me to use the PC as a monitoring device. I can 
use a VNC connection from work to keep an eye on the monitoring PC 
during the day.

When I heard G3XEV finishing a QSO with G3XIV at the weekend I 
frantically tried to find some other inter-G traffic on 40m or 30m (only 
bands I can radiate any sort of signal - 10w from a K2) but it was all a 
bit "long" so didn't bother suggesting a crossband QSO. 

On reflection I think I'd better plough on and start building a TX for 
500, and gain some RX experience, rather than spend time being diverted 
attempting x-band contacts.

I will probably resurrect my old plan to use the AR7030's 1st LO to 
generate my 500kHz. I long ago started a project to mix the 1st LO with 
a 45MHz xtal osc to create a signal source that tracked the dial 
frequency of the receiver. I even had the 45MHz xtal cut and tested the 
idea. Now would be a good time to put it to some use! All that's needed 
then is some gain, a keying cct and some form of PA & LPF. 

Is it worth applying for the NOV before getting the TX built? And is 
anyone aware of any pitfalls to avoid, or vital bits that are needed, 
when filling in the form?

Best 73 and hope to hear you on 500k/c

John GM4SLV

-- 
G-GRP-Club 2377, QRP-ARCI 12384, SKCC 3214
Member : RSGB, ARRL
Shetland Islands (EU-012) IP90GG
Lerwick Radio Club : http://www.gm3zet.org