[Elecraft] [K3] Noise from P3

[John Lemay]

Well, I have undertaken a lot of work to address this problem:-

1. taken apart the P3 and doubly made certain that contact between the
various chassis parts is good.

2. taken apart the K3 and paid particular attention to the contact areas
around the rear panel and IF output area.

3. placed ferrites at both ends of the DC lead to the P3.

4. used the P3 on a separate power supply.

5. placed ferrites on the IF lead between the P3 and K3.

The problem remains. In fact if anything it is a little worse this morning,
but these are not lab measurements.

So, Dxing on 2m with the P3 running is a non-starter for me.

John G4ZTR


-----Original Message-----
From: elecraft-bounces at mailman.qth.net
[mailto:elecraft-bounces at mailman.qth.net] On Behalf Of Jim Brown
Sent: 24 March 2011 06:03
To: elecraft at mailman.qth.net
Subject: Re: [Elecraft] [K3] Noise from P3

On 3/23/2011 9:39 PM, David Pratt wrote:
> That being so, Alan, is there any value in supplying screened cable for
> the power lead rather than the twin 'bell wire' used at present?

Not if it is common mode current, coupled from signal common onto the V- 
wire. Go to my website and study the material on "The Pin One Problem."  
While it is written about audio interconnects, it applies directly here 
to the V- lead.

http://audiosystemsgroup.com/publish.htm

Shielding only matters with respect to DIFFERENTIAL circuit (that is, 
RFI between V+ and V-).

73, Jim K9YC


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