DX40 CW Keying with Keyer

[w9bea]

Good Evening All:

I got my DX40 back on the air after recapping it and fixing a few cold solder joints.

I am trying to use it with a Keyer.  My HAM KEYER HK5 (Sold by Sold by Ham Radio Center in Missouri long ago) seems to "swamp out" when I connect it to the key jack.  It does this whether the transmitter is connected to the grid keying jack or the direct jack on the back of the keyer.  Also my IDIOM CMOS4 kit does the same thing.

When I say it swamps out, the transmitter stays keyed until I pull the keyer out of the key jack on the radio.

I recall as a novice long ago that my EICO 717 worked just fine.  Guessing it was the relay contacts in that keyer that keyed the transmitter.  Well that 717 is gone.

Any ideas on how I can hook up a keyer to the DX40 and having it work okay?

Also, is there any worthwhile mods to make to the transmitter to improve performance or reliability?

Thanks for the input.

73--Wally W9BEA

[WQ9E]

The DX-40 uses cathode keying of the oscillator and final stages so a direct keying output is needed.  But most keyers of the somewhat vintage era (mid 70s through 80s) were designed either for grid block keying a tube type transmitter or direct keying a low voltage solid state transmitter and most weren't suitable for direct cathode keying.

You can use a relay, build your own solid state interface, or the Heathkit Shop sold a universal keying module just for this purpose.  Some of the MFJ keyers were designed to handle cathode keying also so if you are willing to switch keyers that is a possibility.

[w9bea]

I appreciate the info.

I am thinking about lashing together some kind of a relay box for now.

The radio has been a  ball so far.

73--Wally W9BEA