[Amps] More instability problems

[N1BUG]

The regulator supplies power for switching transistors Q1, Q2 and 
the opto-isolator U2 (which handles bias switching). The relay coils 
are powered directly from the ~35V supply (before the regulator) 
with appropriate dropping resistors so that the coils are at 26V 
when energized. R14 sets coil voltage for the RF relays.

I have checked relay timing vs. exciter RF output. I see no sign of 
problems there. The relays pull in very quickly, well before any RF 
output from the exciter, and remain energized. Going back to 
receive, RF drive stops well before the relays switch.

73

Paul



On 04/16/2013 08:40 PM, Jim W7RY wrote:
> I have a question...
>
> Why are you using a regulator for the relay coils on your RF relays?  Are
> you sure the voltage is holding up on initial keyup? Are the relays
> chattering? It would be better if you dispensed with the regulator
> and went with a simple resistor to lower the voltage to the coils if needed.
>
> I'm curious as to your design in this area.

> -----Original Message-----

> http://www.n1bug.com/tech/4CX1500B-6m/6m4CX1500Bsch-hires.jpg


-- 
Paul Kelley, N1BUG
RFI Committee chair,
Piscataquis Amateur Radio Club
http://www.k1pq.org