[Elecraft] Sub-Rx Filters

[Lane]

Richard,

Thanks for your reply, very helpful. Never had the rig to try this before.
Looking forwards to learning to operate in split, diversity, and any other
way possible. Seems like one could write a few books on operating w/
sub-receivers alone.


On Sat, Aug 8, 2015 at 6:37 AM, Richard Ferch <ve3iay at storm.ca> wrote:

> Your understanding of diversity mode is incorrect. What you described is
> NON-diversity mode, i.e. normal or default use of the subRX. In this normal
> subRX mode, the two receivers are on different frequencies - the main RX
> (left ear) is on the VFO A frequency (upper display) and the subRX (right
> ear) is on the VFO B frequency (lower display). The transmitter is on VFO A
> if SPLIT is off, and on VFO B if SPLIT is on. You can use this for split
> operation in either orientation (RX on A, TX on B or RX on B, TX on A), or
> you can use it to monitor two frequencies at once, and choose which of the
> two to work on depending on whether you turn SPLIT mode on or off. You can
> also control which RX is/are heard in each ear with a configuration option,
> but the default is A(main) left, B(sub) right.
>
> Diversity mode is quite different. In Diversity mode, BOTH receivers are
> on VFO A (upper display). You would use a different antenna for each
> receiver (otherwise there is no point) - because the two receivers are
> using the same VFO and are phase-locked, the relative strengths and arrival
> times of signals in the two ears gives you a kind of panoramic soundscape,
> where the signal you want is localized at a particular position in space
> (seems to come from a particular direction), while noise is spread over the
> whole space, and QRM often comes from a different direction relative to the
> signal you want. It's kind of like stereo (diversity) vs. mono
> (non-diversity, both receivers on the same antenna).
>
> In Diversity mode, the lower VFO B display works just like it does with a
> single receiver - it tells you where the transmitter will be when SPLIT is
> on, but it has no connection with either receiver. Do not make the mistake
> of thinking it tells you where the subRX is - that is only true in
> non-diversity mode.
>
> Normal non-diversity dual receive is usable in all modes, including phone
> modes, although the level of activity and the likelihood of split operation
> might be low enough in AM and FM that it might not be economically
> worthwhile to add subRX filters for these modes.
>
> Diversity mode is very useful in CW. It is not useful in digital modes
> (unless someone can write software to emulate what the human brain does
> with the inputs from two ears). I don't know how useful it would turn out
> to be in wider bandwidth modes like SSB, AM and FM - never tried.
>
> I don't know how the filters are installed in a factory build, but the
> arrangement you suggested looks reasonable to me. I don't think there is a
> hardware requirement to line the filters up in corresponding slots in both
> receivers, but from a human interface point of view that makes sense.
> Certainly that's what I did, and like you I left room for the filters I
> thought I would be most likely to want to add later.
>
> 73,
> Rich VE3KI
>
>
> (unknown call sign) wrote:
>
> My understanding of diversity reception is that I can receive two different
>> frequencies and though used more for CW when working pile-ups, it's not
>> something I'd likely use for FM, hence the single FM roofing filter. So I
>> was wondering about installing AM on the sub just so that I could have
>> that
>> as well.
>>
>
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