[TenTec] a T/R circuit question...

[TROY WIDEMAN]

Ronald, I've been using a transistor "switch" for several years with good luck.
The circuit is extremely simple and comes from Ham Radio, March, '89, pge. 38.
The circuit is as follows: -- use a 2N6515 or similar (+250 Vdc at 0.5A max).
             -- connect a 1.2K ohm resistor in series with the rig control relay
out to the base of the transistor.
             -- connect a 1 K ohm resistor from the base to ground.
             -- ground the emitter.
             -- connect the collector to the amplifier relay control.
   That's it, hope this helps. 73, Troy, W6HV
Ronald D Rossi wrote:

> Folks,
>
> Put on the thinking caps! ANY comments are welcome. I have very thick skin.
>
> I am looking for a sort-of design review of a simple circuit I want to try out
> on the T/R connection between my Ten-Tec Omni-D and a Collins 30L-1 amplifier.
> The problem is the RF gets to the amp too quickly or alternatively the two
> mechanical relays inline take to long to energize.
>
> I see two possibilities: 1) replace the T/R relay in the Omni with a fast reed
> relay. 2) suppliment the present relay with a transistor.
>
> Here is my idea for the transistor in parallel with the relay:
>
> http://www.together.net/~larossi/tr_schem.jpg
>
> The Collins 30L-1 is somewhat unique in that the T/R line has the negative
> grid bias voltage setting there. The circuit I am proposing should provide a
> virtual ground at the T/R connection for the time between the transistor
> turning on and the relay in the Ten-Tec kicking in.
>
> Let me know what you think.
>
> --
> 73 de KK1L...ron (rrossi@btv.ibm.com) <><
> QTH: Swanton, Vermont
> My page: http://www.together.net/~larossi/kk1l.html
> My wife's page: http://www.together.net/~larossi
>
> --
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