[TenTec] In praise of older technology

[Kim Elmore]

Ah! I've noticed this but never understood it. At least with the Globe Champ 350, the power output can increase quite a bit off resonance to the right, but the plate current also quickly gets way out of hand. I prefer using it to using my Orion II and my AL-1200 on AM, even though I suspect the Orion II may be a bit cleaner. 

Anyway, I just tried it and, if I'm careful and limit the plate current increase to no more than 5%, the power output goes up just a wee bit faster than I'd expect based on the plate current increase alone. I had always secretly worried that the PA stage wasn't properly neutralized but, after very careful neutralization, I still saw it. I've modded my Champ so that it uses tetrode 8643s rather than the unobtainable pentode AX9909s. 

When I followed this tuning, it was as the very last step in the tuning procedure, so I made no changes to the loading once I'd set the plate current. 

Have I got the procedure correct?

Kim N5OP

"People that make music together cannot be enemies, at least as long as the music lasts." -- Paul Hindemith

> On Mar 1, 2014, at 21:02, "Bob McGraw - K4TAX" <RMcGraw at Blomand.net> wrote:
> 
> I comes from many years of tuning AM broadcast transmitters.  The "right side of resonance" refers to adjusting the tank circuit tuning capacitor to a slightly lesser value of C which is normally turning the knob to the right. One will notice a slight increase in plate current, otherwise a bit more than the current at the actual "dip" value.  Typically about a 2% to 5% increase is adequate.  For my RCA BT the dip is about 425 ma and I run it at about 435 ma for 3300 volts DC.
> 
> With this method one will notice an increase in output power when tuned to the "right side of resonance" by a few milliamps while tuning to the "left side of resonance" the same amount will show a decrease in output.  The input power remains the same for both cases but the output is greater in one case and less in the other case.
> 
> 73
> Bob, K4TAX
>