[ARC5] "Curing Chirp in Command Transmitters"

[David Stinson]

My "2 cents" and worth about 3:

In my experience, if a Command Set transmitter has an 
objectionable chirp, here are the most likely causes:

1.  Something is changing the load on the Osc. 
    after start-up.  Keying the B+ as-designed does
    not result in objectionable chirp in my sets.
    There are several possible causes for this,
     cathode-keying the PA after Osc. start
     being the most common offender.

2.  Inadequate power supply.

3.  Failure to completely refurbish the set (capacitors,
     contact-cleaning etc.)

4.  Leakage, heat failure or other swings 
    in external loading parts.

None of my sets which have been refurbished
incorporate shielded filaments,
extra bypassing or anything else not "as-designed."
although I have listened to Mike Hanz and installed
some "back EMF" diodes in the control boxes and 
modulator.  They exhibit little or no chirp .
Of course dynamotors are good at regulating voltage
under big load swings ;-)

YMMV, of course.

73 Dave S.