[Elecraft] How effective is VFO -B (SUB) receiver?

[Bob K6UJ]

Correct me if I am wrong but I think double tapping A>B button matches both receivers on everything
except the NB and NR settings.  To match the settings also you need to press and hold the A/B button.

Bob
K6UJ





On Feb 21, 2012, at 6:40 AM, Gary Ferdinand wrote:

> Vince,
> 
> I have a loaded K3.  I use split frequently when working DX.  Think of them
> as two complete receivers, not merely two VFOs.  While it is quite possible
> to have totally independent and different settings, for that type of split
> op I frequently match the two receivers in every respect by double-tapping
> the A->B button. This transfers not only A's frequency, but also A's
> settings (bandwidth, frequency, shift, etc.). After a period of adjustment,
> I find that using the A,Ab audio split settings into my headset most
> effective.  I listen to A (the DX) in both ears, while I monitor my transmit
> frequency (the subrx) on my right ear.  Since when I use the Subrx I have
> the settings copied from the main rx, I detect zero difference in quality.
> Strength of sound is selectable.  When the subrx is on, I have the AF Gain
> control for the subrx set up to be a "balance" control, so I can vary the
> relative audio volume of the two.  I find I pretty much balance the two, and
> let the A,Ab setting do the aural differentiation for me.  I should quickly
> note that my roofing filters and their configurations are also identical for
> sub and main receivers.
> 
> Both use ANT1 for Tx and Rx.   It is VERY easy to inadvertently get the two
> receivers on different antennas.  Use b_set to verify the sub is actually
> using the antenna you thought it was both for rx and tx.
> 
> If you have low audio from the sub receiver (with all respect it is best to
> think of that little knob as a receiver versus a VFO), I suggest you first
> make certain you have done the double (or sometimes triple) tap of the A>B
> button.  If you have vastly different settings, perhaps inadvertently set,
> between the two receivers, there can be quite a difference in sound and
> performance.    Once you are certain you've set the subrx to the setting of
> the main rx (the double tap will respond with an A>B ALL message), then it's
> time to verify what filter differences in physical configuration you have.
> For example if you have only the 2.7 kHz filter in the subrx and a whole
> array of filters in the main rx (or vice versa), the subrx will "sound" and
> perform quite differently of course.  Similarly, even with identical filters
> in the two receivers, if the gain and/or offsets of the filters (as set best
> in the K3 utility) are vastly different, and incorrectly so, so might be the
> results.  Also, the obvious but sometimes forgotten RF Gain control... make
> sure the subrx's RF gain is similar to that of the main until you solve your
> problem.
> 
> If all this is ruled out as to why the two receivers sound vastly different,
> try checking your audio settings.  
> 
> By HOLDING config you gain access to the configuration menu.  Here are some
> interesting settings.
> 
> L-MIX-R :  I set this to A,Ab as described above
> SPKRS:  This is for external speakers-read the info note on page 20 of your
> K3 manual
> SUB AF:  I use this set to balance rather than normal, so I can more easily
> adjust the relative volumes of the two receivers.
> SQ:  Make sure you don't have the subrx squelched.
> Check out the troubleshooting section on page 65.  It suggests checking
> settings for AF GAIN (HI) and RX EQ settings in addition to the above.
> 
> Configured properly and with identical filters the sub and main receivers
> are identical in pretty much all respects other than the size of the knob.
> ..and everyone says size doesn't matter ... ;-)
> 
> HTH/73
> 
> Gary W2CS
> 
> 
>> Might some reader who uses (1) K-3, (2) KAT-3, the ATU and (3) the KRX3,
>> VFO-B (SUB receiver) tell me how well the second receiver does its job?
>> 
>> Is the quality and strength of sound from VFO-B comparable to VFO-A when
>> operating split?
>> 
>> What EXACT settings do you use for receiving on ANT 1 via VFO-A and
>> transmitting (up two!) using VFO-B for transmitting AND receiving in
>> SPLIT...and using the same antenna.  Not using AUX antenna?
>> 
>> My FT1000d gives me essentially the same audio on the left channel as in
>> the right channel in split.
>> 
>> With my K3 I have very low audio from the SUB VFO-B.
>> 
>> Am I expecting too much from the K3?  Am I missing something in setting
>> up the K3?
>> 
>> Vince, W1IDL
> 
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