[Elecraft] Samlex 1223 & 1235 power supplies

[Jim Brown]

On Mon, 24 May 2010 13:05:03 -0400, Paul Christensen wrote:

>Jim, that's probably the strongest coupling mechanism most of the time 
>although some receivers have poor shielding from the immediate environment 
>and noise coupling can occur from the SMPS to the receiver's front end.

>An example of this is the IC-7800 and IC-7700.  There's a product review on 
>the web of the IC-7800 that boasts how the reviewer can hear many stations 
>without the need for an antenna!  It's written as if that was a positive 
>attribute of the receiver.  In fact, it only demonstrates how poorly the 
>front end is shielded between the preamp/mixer and the antenna ports.

HAH!  Very interesting. 

>Another disturbing attribute of the '7800 and '7700 is that harmonics from 
>its internal SMPS can be heard when the receiver is tuned from ~ 80 kHz 
>through 160m with decreasing amplitude as the receiver is tuned upwards. 
>Oddly, the noise increases as the antenna ports are deselected. 

Yet another great feature of a $10K radio. :) 

73,

Jim K9YC