[RTTY] SO2R Problem

[Jerry Flanders]

At 09:30 AM 2/14/2012, Tom Martin wrote:
>   Excessive RF took out the front end of the FT-1000MP after 2 hours.
>                           Lost 10 meters on the PRO II on 
> Sunday.  As of Monday morning, no receive or transmit with  the PRO 
> II on any band.


When I first tried SO2R I was concerned about high RF levels from the 
tx antenna coming back down the rx stn line and zapping the receiver 
on the other band(s), so I rigged up a simple RF voltmeter and 
actually measured voltages presented to the rx.

A combination of stubs and filters got it down to <50mV on most 
bands, a max of 200 mv on only one.

This worked for me with pairs of IC756, 756P3, Elecraft K3, and now 
Flexes - I have never had any front end damage from SO2R at 1KW from 
Quadras. My antenna separation is typically 100 ft or so.

What is the most I can tolerate? I don't know, but I assume it would 
take more than a half volt to punch through the typical SS devices in 
the rx front end.

Jerry W4UK