[Hallicrafters] halli "to" keyer

[W4AWM at aol.com]

Hi Joey,

There are three TO Keyers.  The HA-1 and HA-1A are tube type and the HA-4 is 
solid state.  The HA-1 I have has a  front panel recess of about 1/8 inch but 
I have seen others with a recess of about 1/2 inch. It is possible that the 
larger recess is the HA-1A but I am not sure.  There were come component changes 
between the two units but as far as I know, they are otherwise identical. The 
HA-4 has a lower profile and cannot be mistaken for the HA-1 series.

One problem with the HA-1 series is the mercury whetted relay. They tend to 
be a problem as they get older. Unfortunately, they are not adjustable and 
difficult to find.

73,

John,  W4AWM


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