[Elecraft] Interesting K3 QRM problem

[Joe Subich, W4TV]

> Maybe, and if you're right, my suggestion may not help. But you
> misunderstood my suggestion. There is an insert point between the
> T/R switch and the RX input. That's the RX loop I was talking about
> -- you insert the filter there.

The insert point is *after* the PIN diode T/R switches for both the HPA 
(KPA3) and 10W LPA.  Given Vic's description, it is likely the noise is
being generated in one or more of the PIN diodes in the T/R switching
and placing the highpass filter in the insert point will not resolve
the noise.  Vic, you can bypass (disable) the KPA3 to see if the noise
generation is in the KPA3 T/R switch.

73,

    ... Joe, W4TV


On 2014-10-23 4:36 PM, Jim Brown wrote:
> On 10/23/2014 10:36 AM, Vic Rosenthal 4X6GP/K2VCO wrote:
>> It isn't necessary to filter the loop. What is happening is that BC RF
>> is coming into the ANT1 connector of the K3 from the vertical, where
>> it is mixing up with every other signal around, probably in the t/r
>> switch section. Then the IMD products (which are on numerous
>> frequencies) are getting re-radiated by the vertical, and they are
>> picked up by the loop.
>
> Maybe, and if you're right, my suggestion may not help. But you
> misunderstood my suggestion. There is an insert point between the T/R
> switch and the RX input. That's the RX loop I was talking about -- you
> insert the filter there.
>
> 73, Jim K9YC
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:Elecraft at mailman.qth.net
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
> Message delivered to lists at subich.com
>