TX OUT does not come on until all the T/R switching is complete. This
guarantees that when TXEN is returned, all is well to transmit.
Carl Moreschi N4PY
121 Little Bell Drive
Hays, NC 28635
www.n4py.com
----- Original Message -----
From: "Ken Brown" <ken.d.brown@hawaiiantel.net>
To: "Discussion of Ten-Tec Equipment" <tentec@contesting.com>
Sent: Sunday, December 13, 2009 3:33 PM
Subject: Re: [TenTec] OmniVI: question about T/R control logic
> Hi Allan,
>
> You are correct about much of the logic going on inside
> microprocessor chips in the Omni VI. Yet there is still a lot of T/R
> control logic going on is simple resistor/transistor/diode circuitry in
> the Omni VI, and a lot can be learned from the schematics.
>
> My best guess it that "keying" the key or PTT input of the Omni VI
> does all of the antenna switching and receiver muting stuff BEFORE the
> TX EN signal comes back from the amplifier to say "Ok everything is
> ready, now you can really transmit" I do not suggest risking equipment
> damage, or hearing loss, based on a guess though. One way to confirm
> what happens in what order would be to use a dual trace oscilloscope.
> One input could be the PTT or Key input. Then you could probe around
> other places, with and without the TX OUT and TX EN jumper in place, and
> determine the time relation between keying input and PIN diode
> switching, and the dependency (or not) of the TX EN signal.
>
> DE N6KB
>
> Allan Taylor wrote:
>> I now have a pair of OmniVIs and would like to use them in a sort of
>> poor-man's SO2R. Actually I
>> believe what I want to do is called SO2V but will actually be with two
>> radios. What I would like to do
>> is to have both radios functional on receive, and have the alternate
>> radio's (radio B) T/R PIN diode switch activated when the primary
>> radio(radio A) is transmitting, thus protecting the front end of the
>> alternate radio (radio B). Thus the question: Does the PIN diode
>> switch activate a) when the key is pressed/entered, b) when the signal
>> from the QSK loop / amp is returned, or c) at some other time. The
>> easiest solution would be to use radio A's QSK loop in some way to
>> activate radio B's T/R PIN switch. As the control logic is inside a
>> chip rather than in hardware, staring at the schematic does no good.
>>
>> Any takers for this question??
>>
>>
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