In a word "yes".
73
Bob, K4TAX
----- Original Message -----
From: "Kim Elmore" <cw_de_n5op@sbcglobal.net>
To: "Discussion of Ten-Tec Equipment" <tentec@contesting.com>
Sent: Saturday, March 01, 2014 9:42 PM
Subject: Re: [TenTec] In praise of older technology
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@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
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