[ARC5] Why "Noodling" About Sweep Tubes

[Dennis Monticelli]

Well, we might check with the audiophiles regarding the 813 in triode
service.  They have tried just about every triode and triode-connectable
tube.  If we use the tube in class C we can apply those that the
audiophiles have rejected for excessive distortion.

Dennis AE6C


On Fri, Oct 25, 2013 at 10:49 AM, Ian Wilson <ianmwilson73 at gmail.com> wrote:

> Someone mentioned the 813 - seems like a useful possibility, since
> it has the right filament voltage, plate dissipation, and will stand off
> a few kV no problem.
>
> No idea what the triode characteristics would be like.
>
> 813's aren't particularly cheap, but they are much cheaper than 211s.
>
> 803's are another possibility but perhaps getting too bulky to package
> this up and fit into the original location.
>
> 73, ian K3IMW
>
>
>
> On Wed, Oct 23, 2013 at 4:56 PM, Fuqua, Bill L <wlfuqu00 at uky.edu> wrote:
>
> >     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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