[Hallicrafters] HA-4 Keyer Questions

[Mike Peron]

Just bought an HA-4 keyer that should arrive shortly. I didn't know Hallicrafters produced a transistorized version of their venerable HA-1. Can anyone tell me the vintage of this fine looking keyer and its popularity (I'm guessing late 1960s)? Any comments on its performance/shortcomings would be appreciated. Will it key my old SR-150? 

It is arriving without a manual and none is available on BAMA. I see a few web site selling copies so can someone steer me to a reputable outfit? 

Many thanks and 73's

Mike WB6UTW