[CW] OT - AWA Telegraph Station (Landline)
Richard Knoppow
1oldlens1 at ix.netcom.com
Wed Feb 9 17:28:46 EST 2022
I think (but you should check) that no 3-500Z has tantalum
plates. I think Eimac switched to the new material before the
3-500Z was made. Red or orange is the correct color.
I am not sure about the graphite plate tubes. The graphite is
coated with a zirconium gettering material. I would check with RF
Parts to find out the preferred operating conditions.
On 2/9/2022 1:24 PM, abqcooks--- via CW wrote:
> Yes I have the older Eimac 3-500Z in one amp and the plate looks
> metallic. On RTTY I get a dull orange glow which I'm told is
> healthy for gettering the tube.
> But newer RF Parts 3-500ZG tubes have a graphite plate and I'm
> not sure if they are supposed to develop some glow for gettering
> or not. I hate to push the plate xfmr in my Drake L4-B harder
> just to see a glow that maybe is never supposed to happen in the
> graphite plate tubes.
> Guess a call to RF Parts will answer the question. In any case
> the tubes do help heat the shack nicely in winter !
> BTW back to the landline telegraph post, I do have a copy of one
> of those mentioned large Dispatcher Train Sheets.
> It was part of my exhibit. It's probably 4.5 MB in size so I
> can't share it on the reflector but if anyone wants I can email
> it directly.
> Sent from the all new AOL app for Android
> <https://play.google.com/store/apps/details?id=com.aol.mobile.aolapp>
>
> On Wed, Feb 9, 2022 at 2:02 PM, Richard Knoppow
> <1oldlens1 at ix.netcom.com> wrote:
> The Z in the type number means it is designed for zero bias
> operation, an advantage when using it as a grounded grid linear.
> The idea of the glowing plate is really a left over from when
> Eimac used tantalum for plates. This had to run very hot to act
> as a getter. Sometime around the late 1940s Eimac changed to
> another type of plate material which used a zirconium coating
> for
> gettering. These needed to run hot but not like the older tubes.
> Note that it is the plate material itself which is the getter.
> There are also tubes with carbon plates, these also do not need
> to run hot for gettering. I think (but am not sure) they use
> either a separate getter or a coating similar to the metal
> plates.
> One reason Eimac changed from the tantalum plates is that
> hams and others tended to try to run the tubes cool to increase
> their life. This doesn't work for tantalum since it depends on
> high heat to make the getter function work. For modern tubes
> (and
> modern is anything since the late 1940s) any visible glow is
> enough to activate the getter function.
> Eimac still has considerable technical literature on line
> with more details (and maybe more accurate information than my
> ancient memory).
>
> On 2/9/2022 7:35 AM, abqcooks--- via CW wrote:
> > I maintained a setup just like that for our local railroad
> museum
> > for 7 years.
> > Visitors loved it. For kids, we would teach them how to send
> > their name and then give them a certificate of proficiency.
> > It was the most popular exhibit in the museum. Covid shut
> the
> > city owned museum down so I brought all the gear home.
> > Hey, a side question concerning 3-500Z and 3-500ZG tubes.
> The Z
> > tubes were meant to glow a dull orange in operation so as to
> > release getter from the plate.
> > The newer ZG tubes don't seem to get any color. Maybe I'm not
> > pushing them enough or maybe they are not meant to glow
> ?? Any
> > thoughts ? Jim N5KY
> >
> >
> > Sent from the all new AOL app for Android
> >
> <https://play.google.com/store/apps/details?id=com.aol.mobile.aolapp
> <https://play.google.com/store/apps/details?id=com.aol.mobile.aolapp>>
> >
> > On Tue, Feb 8, 2022 at 9:24 PM, David J. J. Ring, Jr.
> > <n1ea at arrl.net <mailto:n1ea at arrl.net>> wrote:
> > I'm sure some might like to watch this very interesting
> video.
> >
> > https://www.youtube.com/watch?v=TvwuOUdwvdI
> <https://www.youtube.com/watch?v=TvwuOUdwvdI>
> > <https://www.youtube.com/watch?v=TvwuOUdwvdI
> <https://www.youtube.com/watch?v=TvwuOUdwvdI>>
> >
> > 73
> >
> > DR
> >
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> --
> Richard Knoppow
> 1oldlens1 at ix.netcom.com <mailto:1oldlens1 at ix.netcom.com>
> WB6KBL
>
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--
Richard Knoppow
1oldlens1 at ix.netcom.com
WB6KBL
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