[AMRadio] Ranger... good news, bad news


Jack Schmidling jack at schmidling.com
Sat Nov 4 19:13:02 EST 2006


Gary Blau wrote:
> Read it again.
> The 6146 screen adjust lets you put the RF out anywhere you want from a 
> low of ~8 watts to full tilt.

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

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