Northern Electric R221-DX Tube Info?

[VA3NGC]

Does anyone have a datasheet or tube information on a Northern
Electric R221-DX Tube? This doesn't appear in any of the usual (RCA)
tube manuals. This tube appears was manufactured in Canada in the mid
1920s.

Charles...

[Dale Carlson]

I Googled the number and came up with a page in Japanese, which is
translated here:

<http://translate.google.com/translate?hl=en&sl=ja&u=http://homepage.mac.com/ryomasuda/VT/num/221/index.html>

It's a type 201 variant. Click on the "201C" link for a chart.

Dale

[VA3NGC]

Thanks. That is what I thought as they were found in an AK20 that had
one 201a in it along with these R221's. Physically the R221's are
different looking than the 01a's as they have a double filament like a
071a has. The filaments also burn much redder than the 01a filaments.

[Dale Carlson]

On Sun, 8 Jun 2008 12:21:03 -0700 (PDT), VA3NGC >
wrote:

>Thanks. That is what I thought as they were found in an AK20 that had
>one 201a in it along with these R221's. Physically the R221's are
>different looking than the 01a's as they have a double filament like a
>071a has. The filaments also burn much redder than the 01a filaments.

If they were mine, and the AK20 was used very much, I'd swap them out
for regular 201A's. I bet their 0.6A filament's life is a lot shorter
than the regular .25A ones...

But what do I know? :)

Dale

[Dale Carlson]

On Sun, 08 Jun 2008 16:37:50 -0700, I wrote:

>... I bet their 0.6A filament's life is a lot shorter
>than the regular .25A ones...

Err, I meant to type "0.06A".

Dale

[terryS]

On Jun 8, 9:48*pm, Dale Carlson > wrote:
> On Sun, 08 Jun 2008 16:37:50 -0700, I wrote:
> >... I bet their 0.6A filament's life is a lot shorter
> >than the regular .25A ones...
>
> Err, I meant to type "0.06A".
>
> Dale

Doesn't that have something to do with older tubes being 'bright
emitters'?

Later, thoriated tungsten cathodes were introduced that could produce
sufficient electrons with lower cathode heater current?

[terryS]

On Jun 14, 11:52*pm, Ron in Radio Heaven >
wrote:
> terryS wrote:
> > Doesn't that have something to do with older tubes being 'bright
> > emitters'?
>
> No, bright emitters were 1 amp filament tubes.
> It took a good battery to run a set full of those.
>
> Ron W4RON

Thanks Ron. Info appreciated. terryS