[Hallicrafters] SR-2000, SR-400 cyclone 2, and SR-150 A level VFO FMing fix.

[Jim Liles]

Good morning:

Corrected definition of effected radios:

All SR-2000, SR-400A, SR-400, SR-150 radios need the 5uf capacitor installed. 

It is installed in the SR-150 level “A” and the Cyclone 2 radios but in the wrong location.  Installed in that location results in a Chirp when transitioning from receive to transmit and transmit to receive.  It was removed in the SR-150 “B” and “C” level radios but is still in the Cyclone 2.  

It was not used in the SR-2000, SR-400 “A” thru “E”, or SR-400A series radios because it caused the chirp.  It somehow found it’s way into the Cyclone 2.

Regardless, it was always in the wrong location.  Moving it to the location in the provided schematic enables it to do what it was designed to do without the CHIRP problem.

It should be installed in all of these radios and has a marked effect on audio quality.  60 cycle side bands on the VFO are the culprit and become worse if the RIT switch gets dirty.

The distortion at low audio frequencies will be absent and when tuning through a carrier the fuzzy sound on the lows will be history.  You will enjoy a crystal clear audio experience.

Thanks the bringing the lack of clarity to my attention.       

Kindest regards Jim K9AXN