[Amps] ICOM PRO III QSK

[Joe Subich, W4TV]

 > Here is the site I was thinking of:
 >
 > http://w0qe.com/amplifier_timing.html

Yes, that's one of the sites I was looking for.  You will notice that
in all of the Icom radios shown, *including* the IC-746Pro and 756Pro,
the HSEND line (cyan in the scope pictures) went high between 4.5 and 9 
ms *before* RF ended in full QSK.

Using the HSEND/SEND output from the ACC jack with a vacuum relay will
result in hot switching the relays on the transition from transmit to
receive and will result in relay destruction unless the amplifier has
some (10 ms minimum) delay on break.

73,

    ... Joe, W4TV


On 12/9/2011 12:23 PM, Jim W7RY wrote:
> Here is the site I was thinking of:
>
> http://w0qe.com/amplifier_timing.html
>
>
> 73
> Jim W7RY
>
>
> --------------------------------------------------
> From: "Joe Subich, W4TV" <lists at subich.com>
> Sent: Friday, December 09, 2011 8:01 AM
> To: "Jim W7RY" <jimw7ry at gmail.com>
> Cc: "rick darwicki" <n6pe at yahoo.com>; <amps at contesting.com>
> Subject: Re: [Amps] ICOM PRO III QSK
>
>>
>> > I have seen that too but it was strictly limited to the IC-7000.
>>
>> The study I saw (not the AD5X article) was not limited to the IC-7000.
>> The "premature release" applied to all of the "small" radios 706/7000
>> as well as several of the full size radios - including 7700, 746Pro,
>> and I believe the ProIII - when using the ACC jack instead of the
>> Send relay.
>>
>> 73,
>>
>> ... Joe, W4TV
>>
>>
>> On 12/9/2011 10:36 AM, Jim W7RY wrote:
>>> I have seen that too but it was strictly limited to the IC-7000.
>>>
>>> 73
>>> Jim W7RY
>>>
>>>
>>> --------------------------------------------------
>>> From: "Joe Subich, W4TV" <lists at subich.com>
>>> Sent: Friday, December 09, 2011 7:12 AM
>>> To: "rick darwicki" <n6pe at yahoo.com>; <amps at contesting.com>
>>> Subject: Re: [Amps] ICOM PRO III QSK
>>>
>>>>
>>>> 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
>>>>
>>>>
>>>> _______________________________________________
>>>> Amps mailing list
>>>> Amps at contesting.com
>>>> http://lists.contesting.com/mailman/listinfo/amps
>>>
>>>
>