[Elecraft] KPA1500 RFI on 10 Meters

[Eric Swartz - WA6HHQ, Elecraft]

Hi Scott,

We have seen this in rare cases on a few 1500s. It appears to be caused by the 
ground connection between the rear RF INPUT SO-239 flange and the chassis.

Very slightly loosening (not too far!) and then firmly re-tightening all four 
screws on this SO-239 connector will insure a good ground connection between 
this connector and the rear panel. (There are lock washers between the nuts and 
the SO-239 inside.)

If the screws are loosened too far, you may have to remove the bottom cover of 
the amp to hold the interior nuts in place while you re-tighten the four 
screws.  (Make sure the 50V power and control cables are disconnected when you 
remove any covers on the amp.)

73,
Eric
/elecraft.com/

On 12/14/2019 1:43 PM, K9MA wrote:
> I guess it just shows how little I've been on 10, but I've had the KPA1500 for 
> over a year now, and I just noticed that when I turn it on, my noise floor on 
> 10 goes up about 3 dB. (And that's from an urban noise floor.) It's pretty 
> flat over much of the band, not typical switching supply noise. Has anyone 
> else experienced this and found a cure? (Other than using the old amp tube.)
>
> 73,
>
> Scott K9MA
>