[ARC5] "Curing Chirp in Command Transmitters"

[Kenneth G. Gordon]

On 6 Oct 2014 at 20:54, J Mcvey via ARC5 wrote:

> Well, when in doubt refer back to the original design parameters. I looked up
> the 1626 datasheet and I think it answers some of the questions of the Why and
> how of the MO circuit. http://www.r-type.org/pdfs/1626.pdf

Ah, yes! Two "issues", 1) keep the voltage difference between the cathode 
and filament as low as possible, and 2) the source for grid bias, how much,  
and why.

> So, from what I gleaned from the notes, the circuit was designed to use a fixed
> DC bias otained from the LV line. I believe that applying AC to the filliments 
> will affect the MO circuit deleteriously . a) 60HZ modulation b) loss of
> stability due to lack of, or improper bias c) possible damage shortening the
> useable life?

Well, Gentlemen, from all the foregoing discussion it seems very clear to me 
now that 1) leaving the circuit exactly as designed, and 2) using DC on the 
filaments may go some considerable distance towards a) eliminating some 
chirp, and b) contributing towards greater stability.

All of this is what I suspected from the beginning. After all, as I have 
REPEATEDLY stated here, IMHO, the designers of our favorite equipment 
were sheer geniuses. I have yet to find anything they DIDN'T address.

Conversely, ham-hacking results in WORSE operation of the equipment, not 
better.

Ken W7EKB