Cathode Keying tubes with...

Brian Carling (Radio G3XLQ / AF4K) bry at MNSINC.COM
Fri Apr 4 12:33:25 EST 1997

Can someone help me decide which scheme is best for cathode keying of
a typical medium tube power xmtr?

I can use either of three parts to pull this off but I am not sure of
their maximum voltage ratings.

TWO of them are small 14-pin DIP relays, and the other is a power
transistor, which is type TIP22

The relays are:

3570 1210 053
07-93 Date code


The voltage I need to be able to switch is typically up to 200V DC or
a little more in the un-keyed condition.

The relays are designed for 24 V DC or 120V AC service respectively,
but I have no idea what the max ratings would be.

The TIP22 is used to switch 24V DC solenoid valves so I am sure it has
plenty of current handling capacity. They typically drive the TIP122
with an iso-optical/darlington device like the 6N139 from HP.

Anyone have any specs on these? Or recommend which I ought to be using
between my CMOS keyer's bipolar 2N2222A NPN output transistor and my
cathodes of the old 1625s etc. ??

I really don't want to go find a horizontal output transistor, as I
would rather use what is already in the junk box here!

It SEEMS like the relays would be the best way to go since they are
probably fast enough for up to 35-40 wpm and could still be also used
for grid-block keying if called-upon for that duty too at some point!

Regards - Bry, G3XLQ / AF4K

More information about the Boatanchors mailing list