[Elecraft] troubleshooting # 4115

[Bud Rogers]

On Friday 02 April 2004 22:49, Don Wilhelm wrote:
> Bud,
>
> How close is your K2 to something that produces an electromagneic
> field (a power supply, a computer monitor, etc.)?  Often the
> electromagnetic field will modulate the BFO causing a distorted
> signal on both transmit and receive.
> Keep the K2 at least 2 feet from such objects.
>
> The fact that you are seeing about 10 volts AC at more than one place
> makes me think you do have an AC field from something on your K2
> chassis.  You might try grounding the K2 chassis to a good ground too
> - and ground your power supply as well to see if that helps.

Hadn't thought about that.  I've been trying real hard to find something 
wrong with my solder work or parts placement.  I've been working on the 
bench, about 2' from my PC monitor and about 18" from the power supply. 
The PS is an Astron RS-5 that I picked up at a hamfest.  The K2 is also 
about 18" from the TR-7 power supply.

I have the internal battery option, so I buttoned up the K2 and took it 
out on the deck, a good ten feet from any AC source.  The symptoms 
didn't change.  I sure was hoping they would.

The symptoms are slightly different on different bands.  On 40 where 
I've spent the most time, the signal is dirty on key down but clean if 
I go into tune, although it does seem to chirp just for a tiny fraction 
of a second as it comes up in tune the first time after a band change.  
Other bands are similar except they seem to take longer to get stable 
the first time after a band change, some as much as 2 or 3 seconds.  
All are very dirty on key down.  That led me to spend a long time 
looking around the BPF and LPF on the rf board. 

Receive audio distorts on all bands when I turn on Spot.  That led me to 
U8 and U10 on the control board, thinking there might be some 
interaction between sidetone and ALC.  Now I'm wondering if I should be 
looking around the synthesizer.

-- 
Bud Rogers	<budr@netride.net>
KD5SZ		EM05vb		K2 #4115