[ARC5] Why "Noodling" About Sweep Tubes

[Fuqua, Bill L]

    Depending on the version of 211 you are replacing. They have plate dissipation ratings  from 75 to 125 watts.
Well over nearly 3 to 5 times that of a 807 or 1625. Also, over twice  that of 6146.  
   Triode connected 807, 1625 or 6146 tubes would behave like zero bias triodes also. So in all cases the bias
would have to be quite different as drive requirements. 
   My email was not only for those looking for a substitute for 211 tubes but for those looking into using
horizontal output tubes for projects. 
  73
Bill wa4lav
 
    
________________________________________
From: arc5-bounces at mailman.qth.net [arc5-bounces at mailman.qth.net] on behalf of Kenneth G. Gordon [kgordon2006 at frontier.com]
Sent: Wednesday, October 23, 2013 2:05 PM
To: ARC-5 List
Subject: Re: [ARC5] Why "Noodling" About Sweep Tubes

On 22 Oct 2013 at 18:24, Fuqua, Bill L wrote:

>   One other thing, when using these tubes you are allowed to let the
>   plate glow.

Well, yes, but in some cases, like with many of the Eimac tubes, plate "glow"
is REQUIRED in order to promote "gettering". Those tubes with thin,
tantalum plates are especially designed for that express purpose.

> Looks great in an amplifier.

I heartily agree! :-)

>    If you use a 4-125A

which is also the same tube as the 4D21 and 6155.

> you can later on upgrade to 4-250A, 4-400A or
>    3-500z

All of which are required to show considerable color on the plate...again to
promote and preserve "gettering".

> (if G-G amp) by
> using larger filament transformer and higher current power supply.

Yes.

> You
> may have to change the input and output ckts depending on design.

Due to the differences in plate impedances caused by the differences in
voltage and current.

> If
> you use continuously variable designs using roller inductors and they
> are conservatively rated no change needed . Sockets are all the same.

Yup.

However, for what Dave wants to do, I think triode-connected 6146 family
tubes would be quite good enough...or even 807s or 1625s or 5933s. They
are all about the same tube anyway.

Ken W7EKB
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