[ARC5] 12 V Power pentode.

Sun Apr 10 20:12:14 EDT 2016

The 6AG7 is truly a great one.  Is there a 6 Volt version with same filament draw as the 6AG7 that could substitute for one of the 12V tubes to follow the 6AG7?? 

73 - Mac, K2GKK in OKC

Sent from my iPad

> On Apr 10, 2016, at 18:22, Kenneth G. Gordon <kgordon2006 at frontier.com> wrote:
> 
> On 10 Apr 2016 at 15:27, Arden Allen wrote:
> 
>>> Does anyone here know of a power-pentode, which is 1) not a beam-tube, 2)
>>> has a 12.6 V filament, and 3) might have an octal base?
>> 
>> Two tubes immediately come to mind, Dave.  The 12V6 and the 12A6.  But both 
>> are beam tubes.  So what's the matter with a beam tube for your application?
> 
> It wasn't David who needed it, Arden: it was I. 
> 
> And I want such a tube for an ECO VFO in a rig in which all the other tubes have a 12 V 
> filament. Also, I am just plain curious if there ever was one.
> 
> Beam-tubes do not make very effective ECOs because their construction defeats the 
> entire purpose of an ECO. 
> 
> In addition, in most cases, what is shown on the tube-base diagram as being a 
> screen-grid, is in fact a pair of "beam-forming" plates, 
> 
> Trying to use such a tube as an ECO results in the oscilator energy being coupled 
> around the "screen" directly to the plate.
> 
> In an ECO, the screen grid is supposed to be the "plate" of the oscillator.
> 
> As I remember it, the ECO also requires a tube with a suppressor grid, so tetrodes don't 
> make good ECOs either: not enough isolation between the oscillator-section and the 
> amplifier-section of the tube.
> 
> The 6AG7 makes a superb ECO tube, but there isn't a 12AG7. The 12BY7 is also 
> excellent in this regard, but it is a 9-pin miniature. Although I could make an adapter for 
> this one, I would rather not.
> 
> Ken W7EKB
> ______________________________________________________________
> ARC5 mailing list
> Home: http://mailman.qth.net/mailman/listinfo/arc5
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:ARC5 at mailman.qth.net
> 
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html