[Elecraft] [K3] clarification on VFO and 2nd Rx

[David Ferrington, M0XDF]

I seem to be very confused about the way VFOa and b control transmit and
want to get some clarification please.

I started (in 2004) with an Yaesu FT-857 and am still using that, the way it
works may well have coloured my understanding. If I may, let me describe
what I understand based on that:

The 857 has 2 VFOs, A & B and at any one time you can see the freq, mode etc
set up on a specific VFO displayed, along with the VFO (id - a or b) that it
is. If I press A/B, it switches from A to B and vice versa. If I have VFOa
selected and Tx, it uses that freq & mode etc to transmit. If I have VFOb
selected and Tx, it uses the settings for VFOb to transmit.
It also has A=B which is slightly confusing and wrong, because it actually
copies VFOa to b - as the A>B button on K3.

A K3 without 2nd RX (KRX3) has 2 VFOs and each VFO can be set up to a
specific frequency and mode, using certain roofing filters and DSP settings
etc.

You always listen and transmit using VFOa settings.
To use the VFOb settings you must tap A/B, which swaps the settings between
VFOa and VFOb, therefore meaning that VFOa is now using the settings that
were on VFOb? And when you transmit, you're using those. When you do this,
the TX and ^ (black arrow above TX) icons will show you as transmitting on
VFOa?
This is pretty much as per the FT-857, I just never thought of it in that
way (I also think of the rig using different circuits to transmit, but I
doubt now that it is).


If you are working split, you transmit on the freq, mode etc., set up in
VFOb - it uses VFOb for transmit. In this scenario, SPLIT, TX and v will be
shown to indicate you are transmitting on VFOb?


If you have the 2nd RX (KRX3) fitted and ON (SUB on), VFOb is used to
control it. In other words, the KRX3 module does not have VFO circuits on
it, it requires a VFO (B) to set it up etc.
All the other rules above apply though?

If the SUB is not on, its pretty much as first described?
Can you even turn on the SUB if its not fitted and if you can, what happens?


Finally, the [REV] button described on pg 15 as exchanging VFO a & b
temporarily - what does that mean - while you have it pressed it swaps and
if you release, they go back? If so, while you have it pressed and you Tx,
does if use VFOb settings?

Thank you Elecraft for making think about what is actually going on inside
my rig - please now help me to think about what is going on inside my head!
Hi 
-- 
Once upon a time a man whose axe was missing suspected his neighbour's son.
The boy walked like a thief, looked like a thief, and spoke like a thief.
But the man found his axe while digging in the valley, and the next time he
saw his neighbour's son, the boy walked, looked and spoke like any other
child. -Lao-tzu, philosopher (6th century BCE)