Jim,
I haven't seen a radio which brings T8 outside of the radio which may
not be of importance to you. Additionally T8 and R8 control the radio
mode so T8 might not actually coincide with the RF exactly but I do
agree with you that T8 goes to +8V BEFORE any RF flows and RF stops
BEFORE T8 go to 0V. I did measure this one time on one of the
IC-756Prox radios but don't remember which 756Pro model. With the
exception of the IC-706 and IC-7000 the other Icom radios all had a
keying line (relay) that did have good timing to use with sub 8mS.
relays in an amp. I may have missed something here but why not use the
key line if it is available? A very simple circuit can hold the Hsend
line active for 10mS before driving an amplifier if you want to drive
the amp from a 706/7000.
There must be a little more to what you want than what I have read.
73,
Larry, W0QE
On 12/10/2011 10:11 PM, Jim W7RY wrote:
> Larry.. I observed the same timing on my 7000. But if you measure T8,
> (8 volts on transmit) I think you will find that the RF does not
> continue after T8 goes back low. I also measured the 7200. T8 is about
> the same on it.
>
>
> T8 controls the transmitter. I don't think that RF COULD flow after T8
> disappears.
>
>
>
>
> 73
> Jim W7RY
>
>
> --------------------------------------------------
> From: "Larry Benko" <xxw0qe@comcast.net>
> Sent: Friday, December 09, 2011 8:10 AM
> To: <amps@contesting.com>
> Subject: Re: [Amps] ICOM PRO III QSK
>
>> Joe,
>>
>> I made measurements on a lot of transceivers which can be seen at
>> http://www.w0qe.com/amplifier_timing.html
>>
>> It needs a little updating but might be useful.
>>
>> 73,
>> Larry, W0QE
>>
>> On 12/9/2011 8:12 AM, Joe Subich, W4TV wrote:
>>> 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@yahoo.com>
>>>> Sent: Wednesday, December 07, 2011 11:12 AM
>>>> To:<amps@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
>>>
>>> _______________________________________________
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>>>
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>
>
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