[Elecraft] Hum on KPA1500

[Bob McGraw K4TAX]

I find it interesting where it is stated  "I have developed a loud 
hum........" which would imply the hum did not exist prior to this point 
of observation.   That being the case, then one must ask "Ok so what has 
changed, been added or removed?".   If it wasn't there before and 
nothing has been changed, then why is it there now?    Something has 
failed, connections have corroded or broken, PL-259's is not tight, coax 
jumper has failed due to movement.  Thus I would suggest one find the 
problem and correct the problem.   I see no value and no point in adding 
to or re-designing a system which previously worked correctly.

Now, if something was indeed  added, removed or changed, that opens up 
another area for investigation.   What was not done correctly to 
accommodate the new configuration?

Jim, K9YC has some good points on bonding, grounding and proper use of 
chokes.

73

Bob, K4TAX



On 4/5/2020 3:50 PM, Carl Yaffey wrote:
> I have developed a loud hum with the KPA1500 on 17m and 15m. A slight hum on 20m. All other bands, no hum.
> It’s power dependent. Loud at full power, hum reduces as power is lowered. Not too bad at 500w.
> Suggestions?
> 73.
>
> Carl, K8NU.
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