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Re: [TenTec] Tentec XCVR Keying Loop and Amp Supply Amp Question?

To: Discussion of Ten-Tec Equipment <tentec@contesting.com>
Subject: Re: [TenTec] Tentec XCVR Keying Loop and Amp Supply Amp Question?
From: Ken Brown <ken.d.brown@hawaiiantel.net>
Reply-to: ken.d.brown@hawaiiantel.net, Discussion of Ten-Tec Equipment <tentec@contesting.com>
Date: Fri, 04 Dec 2009 11:03:15 -1000
List-post: <mailto:tentec@contesting.com>
Hi Dennis
The amp has a pair of RCA jacks for "Key In" and "Key Out." Does anyone know if it is possible to use the "TX EN" and "TX Out" keying loop in late model Tentec xcvrs to key this amp?
Maybe.

I would suggest you read for more details about those ins and outs, or if the details are not there in verbal form, look at the schematic of the amplifier. At the very least you need to determine what voltage is present at the "Key In" when it is open circuit, before you connect it to the TX OUT of a Ten-Tec transceiver. From the description you have provided already, the sense of the logic is compatible with Ten-Tec transceivers. That is to say, pulling the "Key In" to ground is what changes the logical state of the amplifier from "waiting for transmit command" to "transmitting". The problem is that is not the only thing to consider. Some amplifiers have a relatively high negative DC voltage there, for example around -170 VDC for a Heath SB-200. The Ten-Tec TX OUT is intended to pull a fairly low positive DC voltage to ground. If you connect -180 VDC to that output, the best case scenario is it just won't work. More likely though smoke will be released from parts in the Ten-Tec.

Try to keep it an amplifier and not turn your rig into an ampli fire.
DE N6KB

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