Cathode Keying tubes with...

[Scott Cowling]

Bry,

I would use the Teledyne if it is rated for 120VAC. I would NOT use a
transistor, as you will be limited in what you can key.  With the relay, you
can cathode key, grid-block key as well as SS key (if you have any new
radios :-)

I built a Digi-Keyer back in 1970 (remember those?)  It used RTL and had a
PNP output transistor to key my DX-60.  I always wished for a relay output
like my old Eico 717 keyer (3 tubes) had.

73 es GL,
Scotty WA2DFI
Tempe, AZ

At 09:33 4/4/97 -0800, Brian Carling (Radio G3XLQ / AF4K) wrote:
>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:
>
>GUNTHER
>3570 1210 053
>07-93 Date code
>
>TELEDYNE
>641-1
>
>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
>
>