[ICOM] Amplifier keying

[paul at w8aef.com]

I have just completed making some keying observations on my PROII.

During QSK the leading edge of each rf element trails the leading edge of 
key down by 13.8 ms.

During non-QSK the leading edge of the first rf element trails the leading 
edge of key down by 13.8 ms, but the rest of the rf element leading edges 
trail key down by only 4.8 ms.

In all cases the trailing edge of the rf element trails key up by 4.6 ms.

So during QSK my keying will sound light, and non-QSK only the first element 
will sound light.

On to the SEND output available at pin 3 on ACC(1) and ACC(2).

The leading edge of SEND trails the leading edge of key down by .06 to .23 
ms.

The trailing edge of SEND trails the trailing edge of key down by .8 to 1 
ms.

So when the SEND releases at key up plus 1 ms (best case) and the rf 
envelope ends at key up plus 4.6 ms, and I have an external antenna relay 
that follows the SEND line, I will be transmitting into an open line for 3.6 
ms, best case, and 3.8 ms for the worst case.

And the PROII's alc sees no antenna and clamps the output down for the 
subsequent element.

However, I recall someone suggesting using the SQLS line that is available 
on pin 6 of ACC(1).  The leading edge of the SQLS line always follows the 
leading edge of key down by 1.0 ms.

And the trailing edge always follows the trailing edge of key down by 16 ms.

So it would appear that the hot setup for keying my Alpha is to use the SQLS 
line instead of the SEND line.  With a couple of caveats:  That line is used 
for other purposes during FM and AM modes of operation.  While in FM or AM 
and the receive audio is squelched the SQLS line is high and when 
unsquelched the line goes low.  If I never use FM or AM and an amplifier 
then I am in like Flynn.  The only thing to consider is that the SQLS line 
operates oposite to the SEND line.  The SEND line is high during receive and 
lo during transmit, the SQLS line is lo during receive and high during 
transmit.

And then the timing.  The period of a 30 wpm waveform is 85 ms +/-.  If I 
use the SQLS line during QSK my receive time will be down by 25%.  At my 
maximum speed of 20 wpm I will not notice a 15 to 20% reduction in receive 
time so I will be moving my Alpha's keying line from the Icom's relay output 
to the SQLS line.

And then all I will have to do is adjust my CMOS Super Keyer III to add 5 ms 
to each element and I will be sending perfectly weighted QSK cw and not 
switching the PROII's output into an open circuit at the end of each 
element.

Hopefully it will really be this easy.

de Paul, W8AEF