[Elecraft] KPA500 hum; horrendous

[Bob McGraw K4TAX]

Zero hum from mine.  From other comments, be sure the power transformer 
is correctly installed and secured.  It may have moved during 
transportation if you purchased a factory built unit.

As to 20 watts drive and 350 watts out, what bands?    With 20 watts 
drive from my K3S I see 450 to 550 watts out on all bands as seen on the 
amp LED indication and on an external {Bird 43} meter.    The HV is 62 
volts and the current is 11.5 amps into a dummy load.  Amp is operated 
from a 240 source.

73

Bob, K4TAX


On 11/6/2018 10:47 PM, Macy monkeys wrote:
> I'm certainly having my troubles with this new KPA500. The level of hum is unacceptable.
>
> The manual says it is normal to hear hum. With 20 w drive I'm getting 350 watts out but the hum is horrendous when I send CW. SSB not so bad. Is this level of hum normal during keydown? It's room filling!
>
> John K7FD
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