Heathkit SA5010A keyer

[JF]

On 10/10/05 LARRY CORREA wrote on the Heath list:

>I just purchased a SA-5010A Keyer it arrived with a partial manual. The 
>keyer arrived DOA but the problem was simple enough. The connector had 
>come off the regulator. This fixed main problem but it now only works on 
>the right paddle. Does anyone on this list have a fix for the non 
>functioning left paddle? Also does someone have a complete manual for 
>5010A this is the later manual, that they could sell?


I have a manual for the SA-5010;  I don't know how that differs from
the 5010A.  I recall that there was a production error in the original
5010 that required a small wiring change, which I made a note of on
the schematic.  If you want I could scan parts of it, if you know what
pages you are missing.

I wonder if you are trying to use the capacitive paddles that plug into
the front of the keyer:  if so, I would recommend not using them at all,
but instead use regular external desktop iambic paddles (eg: Bencher)
that plug into the rear socket. This is because reliable keying with the
capacitive paddles can never be attained due to variables in capacitive
coupling like changing hand sweat, finger pressure, proximity of other
objects, body posture, etc. No other keyers used capacitive paddles for
those reasons.

As for one paddle not working, there are a few possibilities:

- there are 2 sensitivity pots (accessible through holes in the base),
   one for each paddle - if one is set too far down then that paddle
   will not work;

- during assembly there is the option of arranging jumpers on the
   PCB to allow for right or left-hand users - if one of the jumpers
   was not installed correctly then one paddle will not work;

- if external paddles are used they go through a somewhat different
   signal path (bypassing, among other things, the left/right-hand
   jumpers and the sensitivity pots), so you should try using them to
   see if both the dot and dash external paddles work. If you don't
   have external paddles you can insert a small screwdriver in the
   3-pin rear socket to short first one then the other outside pin to
   the center pin. If they work then you know the problem is in the
   few circuits connecting to the capacitive paddles.

- If one external paddle still doesn't work, then the problem could
   be in one of the keying transistors or ICs, or in the microprocessor.
   If the microprocessor is bad I doubt you can find another, as I believe
   they were specially made for that keyer.

73

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