[Hallicrafters] HA-1 keyer

[V.A. Weiss]

     Bob,

     I experienced the same thing when overhauling my HA-1 last year. Some 
excellent suggestions originated from Roy K1LKY and I would urge you to 
follow them:

     1. New OB2 and 5963s (if you have them)...although this did not solve 
my "extra" dit problem.
     2. Replace all paper caps, C12, C13 (0.02 uf), C1 and C2 across 
multivibrator(0.02) and C3, C4, C5
         (0.001 uf).
     3. Replace all high value resistors, including R1, R6, R17, R19 (2.2 
megW) and R2, R7 (5.6 megW). This
         had the most pronounced effect on eliminating my "extra" dits.
     4. Check the 470 KW   and 680   kW   resistors for drift and replace if 
necessary.
     5. Replace filter caps (20 uf, 250 volt) (Cleaned up sidetone nicely).
     6. Verify R32 (10 W) and R30 (2200 W) not changed in value.
     7. Replace rectifiers with 1N4007s (See my note on number 5)
     8. Of course, add 3-wire plug and fuse.

     Also, be aware that the mercury relay will not operate correctly if on 
its side.

     I played with my TO Keyer for a long time, fussing with the tubes and 
was not able to eliminate the extra and erratic dits added until I replaced 
the paper caps (0.02) and high value resistors.

     Good luck.

     Vern W9STB
     telegrapher at hotmail.com




Might this have
something to do with the suggested use of 5963's in place of the 12AU7's?

Thanks and 73,
Bob, WØYVA

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