[Elecraft] Re: Question re K3 diversity reception

[Jerry Flanders]

I have been using SO2R in some of the RTTY contests for several years 
now. When I first set it up I was concerned about blowing the front 
end transistors in my (then) paired ICOM 756PRO radios. It occurred 
to me that I could simply measure RF voltage coming back in from the 
"other" antenna when under full power and verify that I was below the 
voltage that might damage the input devices. I made up a simple 50 
ohm loaded diode probe for the measurements with my DVM.

The usual techniques of stubs and filters, along with antenna 
separation of apprx a hundred feet, yielded worst-case voltages of 
around 300 mv with 1000 watts tx'ed on the "other" antenna. I assumed 
this could easily be tolerated by the radios and so far this has 
proven correct through 3 generations of different pairs of radios.

I would recommend this technique of actually measuring the incoming 
voltage, then use common sense as to what levels are 
tolerable.  Yesterday Wayne gave some guidance on tolerable levels 
with the K3, removing some of the guesswork.

Jerry W4UK


>"Subject: RE: [Elecraft] Re: Question re K3 diversity reception
>
>Wayne,
>To carry this one step more, what about when I am running multiple K3's on
>different bands at the same time? Do you recommend to use external receive
>bandpass filters on the receive lines if I am using receive antennas on  the
>Receive Antenna and/or Aux input?
>And also use transmit bandpass filters on the transmit antenna input when I
>am using the transmit antenna for both receive and transmit?"
>
>
>Julius Fazekas
>N2WN
>
>Tennessee Contest Group