[Elecraft] Spurious signals heard -- K2

[Vic Rosenthal]

Vic Rosenthal wrote:


> I didn't believe you, because the signal is there with no antenna.  But 
> I decided to check some things.  When I turned of the shack computer, 
> the spur didn't disappear...but it got weaker!  Hmm, what could that 
> mean?  I then disconnected the interface cable from the K2 which goes to 
> the KAT100, the KRC2, and the computer (I like gadgets).  It 
> disappeared!  AHA!  Now I reconnected it and tried disconnecting just 
> the KRC2 -- bingo, all gone.  The oscillator in the KRC2 must be sending 
> a strong signal into the K2 via the interface cable.

Even more interesting:  when I disconnect the cable from the KRC2 to the PC 
serial port, it goes away completely, even though the KRC2 is still connected to 
the K2.  When I reconnect it, the signal comes back...even when the PC is 
unplugged from the AC line.  And when it appears it does so with a little 
'chirp' indicating that something is suddenly starting to oscillate, or the 
frequency of an oscillator is changing.

So it's something in the KRC2 which happens only when the PC serial port is 
connected, even if the PC is powered down.

-- 
73,
Vic, K2VCO
Fresno CA
http://www.qsl.net/k2vco