[Elecraft] Weird signal on 80m on K3 S/N 642

[Lyn Norstad]

Fred -

What you describe sounds like signals I have seen here emanating from a medical facility about a mile away.  It comes and goes, usually during normal working hours but sometimes on weekends.

I believe there are still some diagnostic machines in broad use that will produce signals like that.

Play detective, and check out anything within a mile or two.  Some of these machines, especially older ones, put out a pretty bodacious signal.  Most are higher frequency, but there are still some in use that could produce exactly what you're seeing.

73
Lyn, W0LEN


-----Original Message-----
From: elecraft-bounces at mailman.qth.net [mailto:elecraft-bounces at mailman.qth.net] On Behalf Of Fred Jensen
Sent: Tuesday, July 20, 2021 4:36 PM
To: Elecraft Reflector
Subject: [Elecraft] Weird signal on 80m on K3 S/N 642

1.  Is this list still active?  Seems like ages since I've seen any 
activity.  Wonder if foothill.net has it blocked?

2.  I have a strange noise on 80.  It consists of what appears on the P3 
to be two slightly fuzzy carriers about 3 kHz apart, about S5-6.  
Sometimes that's all there is, but much of the time, the signal slides 
back and forth between them forming a rope-like pattern.  The pattern is 
repeated about 25 kHz lower, and both are synchronized.  The lower pair 
is centered on 3518, the upper pair on 3542.

I've done all the usual [K3 on battery/main breaker off], DFing some, 
and I've searched down to 100 kHz and don't find it.  My P3 is in fixed 
tune mode so the noise display remains constant on the screen as I tune 
across it.  Then, I noticed that when I tune the K3, it disturbs the 
steady back and forth, creating a much finer rope-like pattern.  It is 
totally repeatable, and happens on both the lower and upper signals.  
Tuning either direction does the same thing.  When I stop tuning the Big 
Knob, it reverts to the slow back and forth about once per second.

Wondering if there's something amiss in my K3.  It works normally in all 
other respects, and these signals do not appear anywhere else up to 29.5 
MHz.

73,

Fred ["Skip"] K6DGW
Sparks NV DM09dn
Washoe County
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