[Elecraft] adjacent antennas and potential radio damage

[Julie Royster]

Thanks to those who wrote me privately as well as those who replied on this
list (KL7UW and  K4NH ) regarding the possibility of damage to one radio
from another radio transmitting on a nearby antenna.  For the benefit of all
I am pasting below highlights of the useful information I received.
MANY THANKS!  I learned a LOT from you kind folks.
Julie KT4JR


Dick at Elecraft said:
"At 5 watts it's usually not a problem, at 450 watts, you want to have a bit
of room (maybe hundreds of feet) between antennas.  The radios have some
protection from overdrive.  Carefully planned with antennas end to end or
facing different direction with enough space it's possible to share a band
with multiple K3s.  But if the antennas are coupling sufficiently, it can be
destructive to the front ends of the radios.  I can't offer any guidance
better than you've receive thus far. Every multioperator contest or Field
Day station has to deal with this problem, and there are solutions, but they
require some effort, either bandpass filters to keep energy from nearby
transmitters on other bands, or antenna placement planning, or some
combination."

AB9CA/4 said:
"There are certain orientations which might allow simultaneous operation of
the two stations. If one antenna is a vertical and it can be placed on a
line perpendicular to the mid-point of the Vee you should be OK. This is
when the base of the vertical lies on the vertical part of a 'T' arrangement
with the Vee forming the horizontal top of the 'T' (looking down from the
air). Place them as far apart as possible. There is minimum interaction in
this configuration. With chokes in place and proper dress of the feedlines
you could get maybe 60 dB of isolation between them...

(On Field Day) Our club has used two stations on the same band, usually 20m,
with success. One on CW the other on Phone.  We did it with two wires
arranged as I mentioned earlier, in the 'T' configuration.

Especially note that damage can occur even if one rig is turned off. 
The antenna is still connected internally with power off. To be certain of
avoiding damage it is best to disconnect the antenna from any rig not in
use. And when you connect them be certain of what band the other station is
on (and make sure you are not on it!)."