[Amps] ICOM PRO III QSK

[Joe Subich, W4TV]

I don't have the link at hand or time to go looking for it right now
but I've seen a rather extensive examination of T/R switching that
shows the Icom rigs generally hot switch on returning to receive in
QSK when using the "SEND" or "HSEND" line from the ACC jack.  That
is, the SEND/HSEND signal releases roughly 5 ms *before* the Icom
transceiver stops producing RF.

Drive to the "send" relay includes roughly 5 ms delay necessary to
prevent early release of the amplifier relay.  AD5X has a circuit for 
the ACC output at; www.ad5x.com/images/Articles/QSK%20Delay.pdf.

An amplifier with vacuum relays will need at least 10 ms delay - 5 ms
to overcome the "early" release on the SEND line plus 5 - 7 ms for
normal operation.

73,

    ... Joe, W4TV

> From: "rick darwicki"<n6pe at yahoo.com>
> Sent: Wednesday, December 07, 2011 11:12 AM
> To:<amps at contesting.com>
> Subject: [Amps] ICOM PRO III QSK
>
>> Hi all,
>>
>> Does anyone know it the timing on the ICOM PRO III linear amplifier SEND
>> line is such that the AMP will not be hot switched on FULL BREAK IN?
>>
>> I have an old Alpha 76 and can install vacuum relays for QSK if the timing
>> is OK out of the PRO III.
>>
>> Thanks,
>>
>>
>> Rick, N6PE