[Hammarlund] Possible solution for 6C4...

[Carl]

Johnson went to the 6AH6 very early in 122 production, like after 300 units.
Heath didnt learn from their betters(-;

Carl
KM1H


----- Original Message ----- 
From: "Glen Zook" <gzook at yahoo.com>
To: <hammarlund at mailman.qth.net>; "James A. (Andy) Moorer" 
<jamminpower at earthlink.net>
Sent: Thursday, June 09, 2011 7:17 PM
Subject: Re: [Hammarlund] Possible solution for 6C4...


> The 6AH6 is inherently more stable than the 6AU6.  Heath found out with 
> the Apache VFO.  The first "run" of the transmitters had VFO frequency 
> instability whereas replacing the 6AU6 with a 6AH6 (direct substitution) 
> solved the problem.
>
> Also, replacing the 6AU6 with a 6AH6 greatly stabilizes the Heath VF-1 
> (the same VFO is in the DX-100 and DX-100B), Johnson 122 (and the same VFO 
> is in the Ranger, Valiant, Navigator, Five-Hundred, etc.).
>
> The only thing is that the inter-electrode capacitance of the 6AH6 is 
> slightly different from the 6AU6 and that may require "touch up" of the 
> variable capacitors used in the calibration.  Just the capacitors, not the 
> inductance.
>
> Glen, K9STH
>
> Website:  http://k9sth.com
>
>
> --- On Thu, 6/9/11, James A. (Andy) Moorer <jamminpower at earthlink.net> 
> wrote:
>
> Anyone have a clue as to why the 6AH6 should be any more stable? Is it 
> just the presence of the screen grid?
>
> Any why the 6AH6, which is more of a power tube? Why not our old friend, 
> the 6AU6?
>
> Unclear on the concept, as usual.
> ______________________________________________________________
> Hammarlund mailing list
> Home: http://mailman.qth.net/mailman/listinfo/hammarlund
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:Hammarlund at mailman.qth.net
>
> List Administrator: Duane Fischer, W8DBF
> ** For Assistance: dfischer at usol.com **
>
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
>
>
> -----
> No virus found in this message.
> Checked by AVG - www.avg.com
> Version: 10.0.1382 / Virus Database: 1513/3691 - Release Date: 06/09/11
>