http://www.pvrc.org/~n4zr/Articles/simple_protection_for_the_fledgl.htm
Here is a link that may help? It has been posted here before.
73 de jay/w5jay..
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
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