[TenTec] In praise of older technology

[Bob McGraw - K4TAX]

In a word  "yes".

73
Bob, K4TAX


----- Original Message ----- 
From: "Kim Elmore" <cw_de_n5op at sbcglobal.net>
To: "Discussion of Ten-Tec Equipment" <tentec at 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 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
>>
> _______________________________________________
> TenTec mailing list
> TenTec at contesting.com
> http://lists.contesting.com/mailman/listinfo/tentec
>