[Elecraft] Diversity receive w/o dedicated receive antenna

[Erik Basilier]

Jon, 

My antennas are quite close together and I find that the difference in
polarization is enough to avoid overload. (My verticals are truly vertical
though, not sloping wires.) I usually run just 100W. When I turn on the
1500w amp, it has its own relays clattering rather loudly (vacuum relay for
qsk). Your comment makes me think I should verify that the rx protection
relay isn't activated; if it is then I might not have noticed. In any case,
when running barefoot, I would have noticed, and never did, whether at home
or at Field Day. As I mentioned earlier, the antenna I use for the 2nd rx is
often not dimensioned or tuned for the band in use. However, sometimes it
is, and I never had the problem. Since there is plenty of receive gain, I
would suggest you try a simple resistive attenuator between the 2nd rx
antenna and the radio. Obviously, in that situation it would be better to
use the AUX input than ANT2, so you can't transmit into the attenuator. You
could also consider a dedicated antenna for the 2nd rx which is so
dimensioned that it is not too efficient on any band. I like to have my main
antenna be horizontal and the subreceiver antenna vertical. The horizontal
antenna (a beam at home) is good for dx at low elevation angles. The
subreceiver antenna is mounted lower, but as a vertical antenna it can
somewhat make up for the lower height by the low-angle advantage that stems
from its vertical polarization. I'll admit though that sometimes a dx
station may be inaudible on the vertical. For moderate distances, every
station tends to be easy to copy on both antennas. At the home qth where the
vertical competes with the beam, I generally have to crank up the RF gain a
lot higher for the subreceiver vertical than for the main receiver/beam. At
FD, the untuned vertical competes with a not-very-high dipole, and I end up
with the RF gain at about the same setting for both receivers.

Erik K7TV

 

 

>Probably true. But I very rarely have enough isolation between my antennas.
So if I try diversity, the front end protection relays start buzzing when I
transmit. The consensus seems to be that you shouldn't rely on the relays.

 

The main antenna is simply disconnected while transmitting. Why isn't the
sub-rx antenna? You're absolutely right, as long as I can't use diversity,
dual watch would help me just as much as having a sub-rx does.

 

Jon LA4RT