On 9 Mar 2002 at 2:55, Iowaguy (Dave, W0FLS) wrote:
> I agree with Pete. In this class, you can't expect the sub-rx to do
> everything. Besides, in my own application, the only thing I ever
> really use the sub-rx for in my 1000mp is for finding the DX listening
> frequency. I rarely find myself trying to pull a weak signal out of
> bunch of strong ones on the sub-rx.
Bingo! Although Yaesu saw great prospects in offering a high-end
radio that does true diversity, it was a feature of the FT-1000D
that apparently went largely unused. What we are left with in the
MP and the Mark V is little more like a glorified remote VFO,
as I see it- at least that is how many ops actually use their
sub-rx (and some "D" owners, too).
If that is all the market really wants, perhaps any old sub-rx
design would do fine. I would think that we would want *at least*
as solid a receiver for listening up in the pile, not a lesser one.
After all, up there we may need even better dynamic range,
because we may be trying to dig out a fairly weak signal
(whoever is presently sending to the DX), which is covered by
strong local stations in the pileup. The rare DX op may be
relatively out in the clear if he is working a split. I have been
in many pileups where some DX op is working both the US and
Eu and some of the Eu guys he comes back to are even weaker
than he is- *and* they are closer to loud callers- or covered
by them.
Much depends on how an op wants to use his radio.
If a 'stereo' setup is desired, for listening simultaneously to
the DX and to the pile, then the performance of the sub-rx
should definitely matter. On the other hand, if you just want to
keep punching a button momentarily to monitor the pile, but
find continuous stereo receive distracting, then a sub-rx is
hardly justified at all, and a 'remote VFO' might suffice.
Some hams do better than others at 'multi-tasking'. :o)
I believe that dual receivers used in 'stereo mode' ought to be
completely separate and have identical (excellent) performance.
Would we design a stereo hi-fi audio amp where one channel
has inferior specs? How many people have one favorite ear and
despise the other? :o) Perhaps this is part of the reason why
diversity reception with the "D" never got off the ground.
For true antenna diversity, completely separate receivers are an
absolute must, of course. Why not make them equal, at least
in high-end radios?
Anyway, much of this is academic. The MP and Mark V,
(plus the few competitor radios) do not allow true antenna
diversity reception at all. Besides, pretty much all sub-rx
designs across the board seem to be lower performance than
their companion main-rx.
Here I use true antenna diversity quite often, and 'stereo
receive' (dual receivers, one antenna) almost all the time,
whether I am listening only on the DX frequency or am also
monitoring the pileup.
Any shortcomings in the sub-rx quickly become obvious- I have
noticed several. The "D" sub-rx is still a pretty good one, however.
I don't think it is near as good as the main-rx. Reading pileups is
where it performs worst for me. For small offsets, I can choose to
listen to the pile with the main-rx using CLAR to set my Rx/Tx
frequencies there. This allows me to use the G3TKF Synchro Mod
that makes the sub-rx track the main-rx tuning. For larger offsets
greater than 10KHz, however, I must use the sub-rx in SPLIT mode
I do understand that improving the sub-rx performance in any
radio design would increase the cost. I don't know what Ten
Tec's marketing philosophy is. Perhaps we are seeing the
foundation here for a possible added cost higher performance
model to come later, perhaps even a 'high end' radio? A lot
of their ideas sound very good. I think it might be worth
offering better sub-rx designs, perhaps as an option. There
are some situations where having a sub-rx with performance
compromises does not make any sense to me.
73, David K3KY
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