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

[James Bennett]

Fred - can you get access to another receiver, preferably not another K3? If you can, then unplug your K3 and see if that signal is present on the other rig. Might help pinpoint if the signal is from within your rig or external.

73, Jim / K7TXA

> On Jul 20, 2021, at 4:43 PM, Lyn Norstad <Lyn at LNAINC.com> wrote:
> 
> 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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