[Elecraft] K2 noise on receiver when switching from transmit

[Don Wilhelm]

Mike,

With the blue toroids, you do have the updated KPA100.  Can I assume 
that this problem is a recent occurrence rather than a problem that has 
always been there?

Yes, removing and jumpering out the KDSP2 will likely stop it (or just 
try putting it in bypass), but that is not the source of the real 
problem, it is just the source of the 'pop'.
I would suggest digging into the KPA100 a bit.  Lay the KPA100 on its 
'back' on a book or box to the right of the K2, remove the shield and 
make the diode voltage measurements.  Hopefully that will reveal an anomaly.

73,
Don W3FPR


On 6/10/2015 12:45 AM, Mike Fanning wrote:
> Thanks for the quick reply Don!  I checked the 8R setting and it was indeed set to hold (and is set there again after toggling it to make sure).  I do have the KDSP2 option with the KPA100, but after peeling off the right side panel I see two baby blue toroids.  The K2 is serial number is 5882 and it was purchased in December 2006.  The KPA100 was bought at Dayton in 2009.  I think it took me another year to get around to building it, so it was probably buttoned up about 5 years ago and has been the backup/receive only rig since doing all the alignment checks.  This will be the first time I have really done any transmitting with it since adding the KPA100 (I’ll make sure to revisit the PA screws as instructed).  You have given me something else to check though - I need to pull the KDSP2 and see if that affects the problem.  I’m wondering if there were other upgrades to either the K2 or KDSP2 that might affect this as well?
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