[TenTec] OMNI VI and fast switching amp hook up ?

[Hank Phillips]

Lots of good comments on the reflector already, but I will pass along my 
observations.

Getting an amplifier to close relays quickly enough is not a problem, maybe 
even without resorting to the vacuum relay speed-up circuits.  Even 
sequencing them to close and open in the correct order is relatively easy, 
depending on the relays you have available.  All of this has been covered 
in excellent detail by Rich Measures, AG6K and others.

Background:

When you go key down on the Omni 6+, after some setup delay in the 
transceiver, the "TX OUT" line on J-1 goes low (to ground).  When the 
factory jumper is installed, it pulls "TN ENABLE NOT" on J-2 down and the 
transmitter goes on the air.

This is important:   In my Omni 6+, if you pull "TX ENABLE NOT" down on 
J-2, no matter what the state of the operator's mind or the condition of 
the remainder of the station, the transmitter goes on the air.  This allows 
a failure external to the transceiver to put Omni into transmit, even 
though that may not be what you had in mind.

I believe the optimal solution would be for the Omni to go into transmit if 
both J-2 and J-1 were driven low, that way only a response to the Omni 
transmit request would put the transmitter on the air.  That would require 
additional logic in the transceiver.

I tried to the "Y-cable" trick, and the Omni didn't like the pull-up 
voltage on the opto-isolator I ground to key the amplifier.  You might be 
able to get around that with either an emitter-follower or FET input to the 
amplifier that didn't confuse the existing Omni signalling.  Another 
possibility might be to pick off the collector of Q-16 and bring it out to 
an external connection, and you could still keep the TXHang programmability.

Anyway, I wimped out before solving the problem, settling out of court for 
the relatively inoffensive built-in relay.  If anyone nails this, I would 
like to hear your approach.

Very 73,

Hank

AA4HP


At 01:59 AM 12/1/2005 +0000, you wrote:
>Hi-
>  I have an OMNI VI and a TL-922a amp which I just finished wiring with 
> vacuum relays for QSK fast switching. Works great but, the OMNI relay 
> used to key non Ten Tec amps is annoying on CW. (Not real annoying but....)
>  Of course when not using the amp, which is 99.9% of the time I can 
> switch the relay off and have quiet CW.
>  Is there any reason why I can't tap into the TX EN and TX OUT jumper 
> with a "Y" connection and run the quiet transistor switching to ground 
> since TX OUT does go to ground when its active and then leave the relay OFF?
>
>73 de Dave in NH  K1OPQ
>
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