Even though the Omni 6 and 6+ employs a relay to key an external amplifier,
it is possible to completely eliminate the noisy relay when using the Omni
with most modern amplifiers.
Internally, the Omni uses a NPN transistor to pull one side of the relay to
ground. If your amplifier uses a key line with less than +30 VDC and less
than 200 mA or so (see note below), the connection between the Omni's keying
transistor (Q16) and the relay (K1), on the Control Board can be cut, taking
the transistor's collector out to the Omni's rear panel RCA jack (J7). This
makes the Omni's amp keying line an "open collector," and results in
damn-fast, silent QSK into an external amp.
The second part of this modification requires changing the input to Q16's
base: One side of R29 is normally run to connector "59" on the Omni's
Control Board. Instead, cut the trace and run a small piece of enameled
wire (wire-wrap type) to "TX ACK" on connector "63."
Caveats and Notes:
The newer Omni 6+ uses a Control Board with SMD devices. Use particular
care if performing the mod on this version of the board. It can be done,
and I have done it.
For both versions of the Control Board, I highly recommend replacing Q16
with a transistor that will sink at least 300 mA, and is specified with a
Vceo rating of greater than 150 volts DC. Mine uses a 300 volt SMD
transistor from Mouser Electronics. If you are sure that you will never use
a an amp that employs greater than +30 VDC on it's key line, you can ignore
this recommendation. However, I recently purchased an Alpha PA-70V that
uses a +70 VDC key line and the stock Q16 would have never handled it.
This is not a Ten-Tec approved modification. Use extreme care if you decide
to conduct these changes on your Omni Six.
From: w6ru <email@example.com>
To: Jim Reid <firstname.lastname@example.org>; email@example.com
Date: Saturday, September 19, 1998 10:32 PM
Subject: Re: [TenTec] Omni and 87A
>Have you "turned on" the linear relay in the Omni 6 ?
>This is done in the menu number 1...the "LCO" function has to be set to
>"on". As it comes from the factory it is in the default "off" state.
>I have just the relay key line from the Omni 6 (Relay N.O.) to the relay
>key jack on my 87A hooked up and it works FB....granted I have not tried
>QSK yet...I don't like it.
>Terry - W6RU
>Jim Reid wrote:
>> Well, I have had it for nearly 24 hours now. Still fussing around
>> learning, no QSO's yet. Want to be pretty familiar with things
>> before I jump in the water, hi.
>> Ok, I cannot get the VI+ and the 87A to do their thing. I have
>> tried using the 87A in the keying loop a la Ten Tec linears.
>> The result, whenever the rig is on, it is transmitting!! I
>> connect the Omni TX Out to the 87A relay in; and the
>> 87A "c" key output back to the Omni TR EN. And it
>> is keyed continually ON, no matter what state the
>> 87A is in; Standby or Operate. There is no response
>> of any sort from the 87A, other than it indicates RF
>> power passing through, but, if the Omni is on 20 CW,
>> and the 87 was last on 40, that's where the 87 stays.
>> So the indication from the Omni to the 87 is not taking.
>> When the RF output is continuous from the Omni, and I
>> press the CW key, the sidetone appears and follows
>> the key, but the RF out is constant.
>> From what I read about
>> the Omni Control Board on pg.. 4-16 in my manual, this
>> should work, I think. The manual text says, "the Logic
>> board generates a transmit acknowledge voltage at
>> connector 63. This drives Q11 which sends the key
>> signal over to the Relay on the 87A, as I read it. Then
>> the 87A would send the key signal back into the Omni
>> TX EN connector, and we should be off an running.
>> On the Corsair II, I connected my key signal directly to
>> the 87A Relay input; and then keyed back to the
>> Corsair II key input from the "c" key output of the 87A;
>> that seemed to work fine. Again, tried this with the
>> Omni, and it didn't work either.
>> So what have I overlooked?
>> Puzzled, 73, Jim, KH7M
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