JIm,
I think you find that is caused by 50 hz mains hum .... may be a hum loop
in the audio system / pc-tx earthling , not likely to be psu problem as
frequency is 50 (fund) and 150 ( 3 rd harm)
I had a similar problem with my valve HF set , that was a slight ripple on
the PA HT line caused by the 100% duty cycle of wspr, not part of the
design criteria for ssb/cw , caused spots to appear +/- 100 Hz due to
the full wave rectification in the psu
G .
--------------------------------------------------
From: "James Moritz" <[email protected]>
Sent: Wednesday, September 16, 2009 9:40 PM
To: <[email protected]>
Subject: LF: Re: G7NKS multiple spots
Dear Jim, LF Group,
Me too. I am getting 3 traces (!) from Jim M (he is 9+10 and audible!)
and
a biggish one from Gus too
I am seeing low-level (about -25dB) sidebands on your signal at +/-50Hz
and
+/-150Hz, which are giving rise to the extra spots. I think something
similar is happening when you receive my signal. I am not getting similar
multiple spots from other nearby stations, nor am I seeing the same
sidebands on other strong signals, so I think they must originate in your
station somewhere - possibly audio being affected by mains noise, or some
sort of residual FM of an oscillator in your rig?
Cheers, Jim Moritz
73 de M0BMU
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