[TenTec] Interfacing to 444 Amp

[Dave]

your comments, your thinking look good - I have the 444 and Omni C - 
no stability problem any band.....
definitely use the T voltage from transceiver.... nothing else works - 
I have attempted with various older Kenwood and amp would default/shut 
down.

good luck,  amp has, in my opinion, been given a bum wrap.
DAve K8BBM


On Tue, 27 Apr 2004 13:58:48 -0500
"Jim Brown" <jim at audiosystemsgroup.com> wrote: 
> I am the lucky (?) owner of a used 444 that the previous owner used
> with an Omni C. Yes, I know the output devices are long unavailable,
> that it could be unstable, and that Ten Tec wishes they had never 
> made
> it. All that aside, I want to use it with my Omni V and my TS850. 
> 
> What I've learned so far by studying the 444 manual, the Omni V
> operating manual (sad, compared to my Omni A manual), the TS850 
> manual,
> and the keying traces in QST product reviews:
> 
> 1) All of these radios accomplish QSK by delaying transmit by 5-15 
> ms
> after the key has been pressed. The keydown signal is called the
> T-line, and is used to run the antenna relay. The transmitter is
> actually keyed by a delayed version of the keying signal. In the 
> Omni
> A, it's about 5 ms, in the Omni V and TS850, it's more like 10-15ms. 
> 
> 2) The Omni A and the TS850 bring the T-line out to the amplifier
> interface connector. On the Omni A, it's pin 2 of the 9-pin Molex 
> that
> also runs the amplifier's bandswitch. It's pin 7 on the TS850 
> amplifier
> connector. 
> 
> 3) The Omni V does NOT bring the T-line outside the radio, so I've 
> got
> to drill a hole, add a connector (RCA, BNC, or whatever).  
> 
> 4) TheHercules II use a different keying system -- the amplifier 
> keys
> the radio and does the delaying -- and the Omni V (and later) are
> designed to work that way. 
> 
> 5) The 444 is designed to work with the Omni A, so 5 ms is enough
> delay. I interpret that to mean that the additional delay provided 
> by
> the TS850 and Omni V will work fine with the 444 Hercules. 
> 
> 6) The keying signal (T-line) is buffered by the 444 (a 2N5087), 
> thus
> the 444 doesn't load the T-line, so I I don't need to do anything
> special to isolate the T-line. 
> 
> 7) The TS850 lacks a receive antenna input, so I need to add one. 
> That
> also involves drilling a hole. 
> 
> 8) With the Omni V and TS850, I key the radio and it keys the 444
> amplifier. 
> 
> Questions:  
> 
> Can anyone find anything wrong with what I've outlined?  
> 
> Any problems I haven't thought of? 
> 
> I see two sets of T-R relays in the 444 -- one seems to be 
> essentially
> a PTT relay that switches the amplifier to transmit and would be 
> held
> in by the VOX delay. This one seems to be driven by grounding the 
> relay
> jack. The others are a pair of QSK reed relays keyed by the T-line 
> that
> short the receiver input and connect the ampfier to the antenna. Can 
> I
> run non-QSK by not using the receive antenna input of the 
> transceiver
> and keying onlly the PTT relay? 
> 
> Jim Brown K9YC
> 
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