>
> My SB220 contains a small transformer with two windings. One winding
> supplies the filament voltage for the 3-500zs and the other supplies
> bias and relay voltage at 120volts. One side of the relay coil is
> connected to this little half wave supply. The other side of the relay
> coil goes a jack on the back of the linear. When this jack is grounded
> it closes the relay and the linear goes into the transmit. From the
> banded end of the diode rectifier, a 20ufd, 160 volt electrolytic
> capacitor is connected from this point to ground. Without this
> capacitor the relay will not close. It just chatters from the pulsating
> dc voltage. Just what you'd expect.
>
Install a larger (voltage) capacitor or a series resistor (47 Ohm 2 watt)
ahead of the capacitor. 120 volts * 1.4 (for a capacitor input filter)
is 168 volts on the capacitor ... it's too close for comfort particularly
if the line voltage is a little high. Also, make sure the polarity is
correct on the capacitor!
73,
... Joe Subich, W8IK/4 ex-AD8I
<W8IK@IBM.NET>
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