[Top] [All Lists]

[Amps] T-R switching

Subject: [Amps] T-R switching
Date: Thu, 30 Aug 2007 02:34:03 +0000
List-post: <>

I preface this with I am not a EE (I write code for a living) ;)   

With the help of a few books, I have attempted to design and build a circuit, 
but I am having trouble making it work consistently without destroying various 
components.  I have at least two problems that I know of.

The first is that either T17, or Z1, fail after some time, 30 minutes to an 
hour which results in the TR switch staying in the keyed position.  

The second is somewhat of a stranger issue, perhaps they are related.  This 
circuit is going into a small solid state amplifier circuit 5 - 10 watts in 
will produce 50 - 100+ watts output.  When the TR is "working", it seems if I 
excite the amp with 1 to 5 watts, the TR circuit relay RL17 switches on and off 
extremely rapidly, as if RF were getting into the relay and causing it to 
switch on/off, this produces almost a buzzer type effect.  As I increase the 
exciter power above 5 watts, the relay starts holding and behaves normally 
(until I get an all out failure).  I've tried what I think is obvious, ferrite 
beads, and 0.1uf cap from the vcc to ground at the relays, still no change in 
behavior .

 RL17 & 18 are RTE24012F, SPST2 in my schematic is the input from the key 
circuit of the exciter, in this case, a Kenwood ts680 on 6 meters.  SPST1 is 
just a delay circuit and not populated right now.  RL18 is populated, but not 
connected, and it does not buzz, only RL17.  

If anyone has any comments or suggestions on things to try, I've pretty much 
run out of ideas, the circuit works forever as long as it's not connected to 
the PA strip.

Thanks, 73s,
Paul kg7hf.
Amps mailing list

<Prev in Thread] Current Thread [Next in Thread>