[Elecraft] KPA1500 hum - problem solved

[Jack Brindle]

When he added the amplifier, the return currents on the coax became much greater. 
The second problem is that the switch then added the return currents of the vertical to those induced into the dipole and made things worse.
I see the need for chokes on BOTH antennas. Makes sure they are heavy duty. The best advice is in the choke handbook at K9YC’s web site.

73!
Jack, W6FB


> On Apr 5, 2020, at 3:17 PM, Bob McGraw K4TAX <rmcgraw at blomand.net> wrote:
> 
> If it worked correctly before then why would one need to add a choke?  
> 
> Check connections, feed line, matching unit, and radial ground system at the antenna. 
> 
> Bob, K4TAX
> 
> 
> Sent from my iPhone
> 
>> On Apr 5, 2020, at 4:52 PM, Buck <radiok4ia at gmail.com> wrote:
>> 
>> I would bet your coax shield is acting like a radial and bringing RF back into the shack.  Need a choke.
>> 
>> 
>> k4ia, Buck
>> K3s# 11497
>> Honor Roll  8B DXCC
>> EasyWayHamBooks.com
>> 
>>> On 4/5/2020 5:33 PM, Carl Yaffey wrote:
>>> No hum using a dummy load.
>>> No hum using a dipole.
>>> Hum only with my all band vertical.
>>> Thanks for the suggestions.
>>> 73
>>> K8NU
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