[Elecraft] How effective is VFO -B (SUB) receiver?
Gary Ferdinand
alaparos at taconic.net
Tue Feb 21 09:40:23 EST 2012
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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