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

[Ken Brown]

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