Dear Roger,

please don't give up too soon! If you were willing to go to longer symbol 
durations (say a minute or more), you could certainly cover several hundred 
kilometers.

A rewarding target would be to reach the F1AFJ grabber, about 600 km south of 
you. It is remarkably sensitive, and I believe that the noisefloor in the 24 
mHz 
FFT bandwidth.may sometimes be as low as 10 nV/m. Across a nighttime single-hop 
path, 20 uW ERP from you could theoretically produce about 30 nV/m there - ie. 
a 
comfortable 10 dB SNR.

Good luck, and thanks for sharing your good work.

73, Markus (DF6NM)

----- Original Message ----- 
From: Roger Lapthorn
To: [email protected] ; G6ALB
Sent: Friday, September 03, 2010 10:54 AM
Subject: LF: 137kHz activity

My QRPp 137kHz experiments are now on hold until next week as we've our younger 
grandson and his mum and dad with us for a few days, so I lose the shack as it 
doubles as a bedroom. Thank you for your reports thus far to my QRSS3 and WSPR 
tests.

>From the tests this last couple of weeks I'm beginning to think Mal G3KEV was 
right.

On 137kHz QRP just does not "do the business", unless one is prepared to erect 
a 
much beefier antenna, run more power than 5W from the PA, and be very patient 
with slower QRSS and DFCW modes. My "sphere of influence" would seem to be out 
to about 75km maximum with the system I currently have. Going up in ERP 
requires 
me to look more carefully at higher output PAs, heatsinking, rating of 
capacitors, thicker antenna wire (more obvious in the air to neighbours). It 
moves me away from my, self-imposed, QRP ethos in which I wanted to explore the 
limits of a truly simple QRP station on 136kHz. It has been a great learning 
experience for me though and there are still a few more dBs to squeeze out yet.

I'll be on again next week from Monday, probably giving 137.5kHz WSPR a good 
go, 
before drawing the tests to a natural close and leaving the band to the big gun 
stations.

73s
Roger G3XBM

-- 
http://g3xbm-qrp.blogspot.com/
http://www.g3xbm.co.uk
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G3XBM   GQRP 1678    ISWL G11088