Hello John,
My K3 is driving my 30L1 without any problems. However I did need to
construct an interface to key the amp. The key line is a -170 vdc and
requires 100 ma. to actuate the relay. You can check this by measuring
the - volts before keying. And then put a ma meter in series to ground
and measure the keyed current. No drive required for these measurements.
I used a NPN high voltage transistor, (NTE 397), for the interface.
And a couple of resistors all in a small plastic box.
The collector is attached directly to the keying line of the 30L1. I
attached the emitter of the transistor the 12 dc supply on the rear
apron of the K3. I attached the base of the transistor through a 2.7k
resistor to the key output on the rear apron of the K3. Between the base
and emitter I placed a 4.7k resistor. Noting trick about the
arrangement but you want to be sure that the transistor is saturated for
cool operation.
Smith Bradford
W9HAK
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