[Elecraft] 12 meter K3 RFI from nearby FM station

[Jon Zaimes]

Yes, that is the case. Hearing it on both of my K3 transceivers with only
the 12v power cable connected, nothing else (listening on speaker).

Thanks to all for the tips. Still absorbing the advice before proceeding.

73/Jon AA1K
Felton, Delaware
www.aa1k.us

-----Original Message-----
From: Elecraft [mailto:elecraft-bounces at mailman.qth.net] On Behalf Of Alan
Sent: Thursday, February 11, 2016 12:04 PM
To: elecraft at mailman.qth.net
Subject: Re: [Elecraft] 12 meter K3 RFI from nearby FM station

On 02/10/2016 03:57 PM, Jim Brown wrote:
> Yes, this hit me between the eyes as well. The K3 has Pin One Problems 
> at many (most?) connectors, so RF current flowing on shields of cables 
> plugged into those connectors will couple into the K3. I've been 
> preaching to Wayne about Pin One Problems since 2004, when we met in 
> Dayton.
>
> If the problem is around 90 MHz, I'd use multiple one-turn and two 
> turn chokes with #43 material on every cable except the SO239 output, 
> which IS actually bonded to the chassis. Also choke the power cable.

But it sounds like he was still getting the problem with no cables connected
to the K3:

On 02/10/2016 06:58 AM, Jon Zaimes wrote:
...
 > Even when ALL cables are removed (only the power lead connected).
 > Grounding or ungrounding made no change. I tried the radios on a  >
battery but still had the RFI. Tried some ferrites on the power  > lead but
no change.

I suppose it could be a "pin 1" problem on the power leads.  It's kind of
hard to avoid that with an Anderson PowerPole connector.  Probably
additional low-pass filtering on the DC input would help.

Alan N1AL

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