Message-ID: <4FFE753D.4060507@gmail.com>
Date: Thu, 12 Jul 2012 06:57:01 +0000
From: John P-G <gm4slv@gmail.com>
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Subject: Re: RE : LF: Opera QRP test on 477
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Stefan, LF


01:47    477 DK7FC Op4 +0 dB

Best spot of the night, 0dB

I notice that today the spots ceased around sunrise - no residual 
groundwave at this power level.

As for "hearing" - I don't know.

A few years ago (September 2007)  Finbar EI0CF and I did some QRPp tests 
on 501kHz using CW and I managed to read a 4-figure group he sent with 
TX power of 100mW. I think we may have done some more tests at lower 
power, but I can't find the details at the moment.

I generally find, on HF as well as MF, that my WSPR reports are 10dB 
better, or I need 10dB more power to get equivalent reports, between 
myself and other stations. I assume this is due to a low local noise floor.

I've done some 5MHz Olivia operation over the last few months, and found 
similar results, even with stations in "rural" locations.

Summertime isn't the best for weak signal work on MF due to the QRN, and 
the long daylight period at this latitude, but I've had some good 
results, even in summertime, which is why I thought I'd put a grabber up 
now, to see what's possible.

My Perseus is currently showing a noise floor of -120dBm in the marekr's 
122Hz RBW, or -104dBm in the 8.8kHz demodulator RBW.

https://dl.dropbox.com/u/3551430/gm4slv_mf_noisefloor.JPG

This is around -140dBm/Hz, between QRN bursts. I imagine this is rather 
lower than most MF stations experience.

I hope to be in a position to transmit on 502kHz soon, but other 
commitments are delaying my progress at resurrecting my MF TX.

Cheers,

John
GM4SLV


On 11/07/2012 23:03, Stefan Schäfer wrote:
> John/GM4SLV, MF
>
> You must have a superior receive system and location!
> I just got -8 dB from you and i have only 1 W transmitter power here.
> Can you even hear me at this level?
> Maybe i should connect the VFO without the PA, in series with a 1k pot
> to adjust to 100 mW and 10 mW TX power? :-) It works like on 40m...
>
> 73, Stefan/DK7FC
>