On Sun, 13 Apr 2003 13:34:15 -0400 "Jim White, K4OJ"
<k4oj@tampabay.rr.com> writes:
> while we are on the subject of the six pak...
>
> any consensyus as to a cure for relays that sometimes do not
> close...
> WX0B told me to stretch the springs slightly and that did not seem
> to
> fix the problem which seems to keep coming back...
>
> I woukld run the relays a little hotter if I knew where to find a
> zener
> that would run just a little higher...I have a supply which can
> supply >
> 12V for the box but the zener defeats that...
>
> thoughts? respond and I can summarize...
>
> Thanks,
>
> Jim, K4OJ
I use 13.8 vdc regulated on mine, and have never had a problem.
I'd worry about stretching the springs. The normally-closed
contacts of those relays carry signals too, and they could
become intermittent if the tension is lower.
You could add some regular forward-biased diodes in series with
your zener. Each one adds about 0.6 volt. The relay coils would run
hotter though, and the heat is an e-squared function, so it goes
up pretty fast. Those coils can be energized for hours at a time.
Another idea is to use a "hot-shot" circuit, with a higher supply
voltage, and a resistor in series. For example, you could use
24 vdc, and a resistor equal to the DC coil resistance of the
relay. When power is first applied, almost the entire 24 vdc
appears across the relay coil, and helps to snap it in. This
happens because the coil is inductive. After a few milliseconds,
the voltage will split 50/50, and the coils will run at normal
temp. You would need 12 resistors, one for each relay.
Dave Hachadorian, K6LL
Yuma, AZ
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