After buying my FT-1000 I became interested in doing some
polarization diversity receiving with two antennas. As a quick
check, I tried the Yaesu with my Kenwood TS-930 on 30
meters, using a high horizontal dipole plus a 225ft 'cone
of silence' optimum length Beverage. Results were quite
encouraging, so I went ahead and bought a BPF-1 unit for
the Yaesu. I also added the 600Hz filter for the sub-rx, which
really is essential for CW work. Diversity adds a wonderful
'presence' to received signals which is hard to describe-
it must be experienced first-hand. The improvement in
intelligibility is well worth the effort it takes to get it. I was
quite pleased with the results, so I added the G-mod which
allows tuning both main and sub-receivers around the band
using only the main VFO. The SPOT switch is adapted for
switching this feature in and out. Another mod I definitely plan
to do is the one by K0FF, which regains the capability for
the main rx to listen on the Beverage antennas when a BPF-1
has been installed (and also for the sub-rx to listen on the
main rx/tx antennas, even on different bands).There are not
many ham transceivers on the market that have a totally
separate sub-receiver, from separate antenna jacks all the
way through to separate audio channels. Tuning up and down
the bands in true diversity mode is a real treat! Now I am
'spoiled' by it, and single-channel, single-antenna signals
have a muffled or 'muddy' sound by comparison. Note that
some ham transceivers have sub-receivers but share the
bandpass filters or even an IF strip. Only with the added BPF-1
is the FT-1000 able to do true antenna diversity. (How does the
MP handle this?)
My observation is that diversity is especially worthwhile for the
low bands, 30, 40, 80, and 160 meters. If two antennas are
available and both can hear a signal reasonably well, your ear-
brain filter will take care of the rest, even with fairly different
signal levels between the two. Probably using two antennas
of opposite polarization will give the best results, but using
space diversity with antennas of the same polarization might
also provide some improvement in intelligibility. I was surprised
to learn that some FT-1000 owners have the BPF but do not use
it much; also some do not use the radio's DUAL function, but
rather seem to treat the separate sub-rx mainly as a remote
VFO for split transmitting, or perhaps as just another memory.
While in diversity mode, you can still use the CLARifier in the
radio for rx/tx splits up to 10KHz- this should cover many or
even most split transmit situations encountered, though certainly
not all of them. For very crowded or noisy band conditions, one
of the narrower Inrad filters in the sub-rx would be a good idea.
So far, I have only had one incident where I felt that the sub-rx
cw IF was too wide. For now, I plan to deal with that problem
using my Timewave DSP-599zx in the sub-rx audio channel.
73, David K3KY
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