Hallicrafters HA1 Keyer

Rinkie & Ron Pollack rinkies at ADELPHIA.NET
Mon Apr 12 00:18:31 EDT 2004

I've had this nice keyer for at least 30 years, and I'm kind of embarrassed
that I can't figger out this problem, even tho I'm not a technical type.

Cannot get the sidetone to work.  Here's what I've done:

Checked that the jumper is in place on the accessory socket.

Replaced the tube (V4)

Replaced the NE2 bulb

Replaced C8 and C9

Checked tube voltages

Checked speaker

Checked resistances of resistors and pot.

Checked the relay.  (Am using the relay contacts meant for the sidetone to
key a Heathkit code practice osc for temporary sidetone!)

Still no sidetone!   It appears that the oscillator runs continuously and
the output of the transformer is keyed by the relay.  I assume that the
transformer is ok, since if the primary were open then there would be no
voltage on the plate, and I checked continuity on the secondary.

Should the NE2 bulb be lit all the time ( It is not).  Is there any way to
check the bulb itself?

With fewer than a dozen parts in this circuit, it should be a cinch!  What
am I missing?

Also, occasionally the keyer will give just dots in either the dot or dash
position, but it goes away quickly.

I have used the keyer on and off for many years, but with a  SB401/303 combo
that has a built in sidetone, so I turned the volume down on the keyer, but
I seem to remember it not working years ago, but I never bothered to check
it out because I wasn't using it.

Any ideas on either of these problems?


Ron K2RP

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