Yes, the screen mod can be made on its own, as can most of the others.
Although it will change the Z the modulator works into it will not have
a dramatic effect on audio performance which, quite frankly, already
isn't too hot with the stock audio stages and mod xfmr. (Hence the more
involved audio mods.)
I certainly would not lump a screen adjust mod into the same power
reducing option basket as a T connection and a dummy load or reducing
loading, both of which I would agree are bad (lazy) ideas.
The compromise in adjusting the screen is a small one.
Try it and see, if you don't like it it's simple enough to take it out.
FWIW it worked great for me.
If all you want is to reduce the RF to feed a linear then just do the
screen mod, or something like it. Many ways to skin this cat. All
depends how complex you want to make things.
g
Jack Schmidling wrote:
Guess I missed that "detail". Question though... can that change be made
on it's own?
Secondly, I found this contrary statement on another site....
................
Most often mis-modification:
Reducing output power when driving a linear amplifier through the use of
a T connection and a dummy load and/or reducing loading or screen
Voltage. This situation wastes one of this rig's better resources namely
modulator headroom. When altering the R.F. final's impedance through
reduced plate current, the modulation transformer no longer sees the
designed load.
The correct way to reduce output power is to use an external plate
supply with a Variac on the primary or switch the low B+ Voltage to the
final (removing the high B+) through the accessory jack. Either way the
high B+ is left on the modulators. This gives an immediate improvement
to the audio as the modulator requirements are now cut way down without
forcing the modulator into an unknown load. With the accessory low power
mod, the rig will put out abour 12-14 Watts carrier which is a good
level for driving quitea few linear amplifiers. Every available effort
to clean up audio distortion should be considered when runnung QRO AM!
................
Whom do I believe?
js
______________________________________________________________
AMRadio mailing list
List Home: http://mailman.qth.net/mailman/listinfo/amradio
Partner Website: http://www.amfone.net
Help: http://mailman.qth.net/mmfaq.html
Post: mailto:AMRadio@mailman.qth.net
