thanks for the idea. I do believe the hf2500dx has the qsk feature,
however I will have to confirm this when I get back home. In any event it
would appear that the linear relay on the OMNI is more than up to the task
of switching this load in non-QSK mode which I'd be quite happy with in any
>------- Original Message -------
>From : Ken Brown[mailto:email@example.com]
>Sent : 6/4/2005 9:17:37 PM
>To : firstname.lastname@example.org; email@example.com
>Subject : RE : Re: [TenTec] Keying Amp with my new Omni VI+
>You may not even need to use the relay in the Omni VI to key the
>amplifier. The TX OUT line on the Omni VI which is used with Ten Tec
>amplifiers is connected to the open collector of Q11 (on the Control
>Board) a MPS-6514. When connected to a Titan 425 amplifier there is 28
>VDC from the 425 connected here. That transistor pulls this line low
>with 10 k ohms to the +28 VDC supply. That works out to 2.8 mA if Q11
>pulled it all the way to ground. This does not prove that the MPS-6514
>can handle 80 mA, but it can certainly handle 28 VDC so 12 VDC should
>not be a problem. I suggest looking up the specs on a MPS- 6514 ( check
>out the fairchild spec sheet I found) to see if it can handle 80 mA. If
>it can, then you need not activate the relay in the Omni VI, and you can
>just use the open collector TX OUT line of the Omni to key the HF-2500.
>I found a spec sheet which says the maximum collector to emitter voltage
>is is 25 Volts, which is kind of strange since the Titan 425 puts 28
>volts on it. It also says the the maximum continuous collector current
>is 200 mA. That indicates to me that you could safely switch 12 VDC at
>80 mA directly with the open collector TX OUT of the Omni VI and not use
>either an intermediate relay or even the Omni VI internal relay.
>If the QRO HF-2500DX is not QSK capable, and you need a "hang time" on
>the keying, you will probably want to opt for relay control.
>Here is what I found on the MPS-6514:
>> whether I will require an
>>intermediate keying relay between my "new" Omni VI+ and a QRO HF-2500DX amp.
>>Amp manual states that the t/r relay should be capable of switching 12v@
>>80 ma. The OMNI op's manual indicates its to be used to switch low
>>voltage DC only but does not provide a current rating.
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