That's an excellent idea Bill. I will have to try that the next time I test GS-35B's. Don't know if I will be able to see much with the ceramic but I would bet it would be easy to see with glass tubes. Maybe someone else could report on that one. One of these new small space age magnets should produce enough magnetic field. Stuck on the end of a large tywrap should make it safe enough.

73, Tony W4ZT

Bill Turner wrote:

ORIGINAL MESSAGE:

On Sun, 24 Sep 2006 17:59:19 -0700, R L Measures <r@...> wrote:

They can't reverse direction quick enough?

------------ REPLY FOLLOWS ------------

Perhaps so, but if they can accelerate to a certain speed in the half
inch or so between cathode and anode, why could they not decelerate an
equal amount a half inch after passing the anode? They would be
stopped in mid-space and immediately return to the anode like good
little electrons should. :-)

Or maybe the glass is too close to the anode so there is no time for
reversal before impacting the glass?

Bill, W6WRT

ORIGINAL MESSAGE:

On Sun, 24 Sep 2006 13:38:32 -0400, Tony King - W4ZT
<w4zt-060920@...> wrote:

We had a discussion about fluorescence in ceramic tubes some time back
and I posted a few pictures of GS-35B's glowing in the dark
<>. The best explanation was electron bombardment
as opposed to soft X-rays. Just not enough voltage to accelerate the
electrons enough to generate the X-rays. Most of the pictures were taken
with less than 2500 Volts on the anode.

73, Tony W4ZT

------------ REPLY FOLLOWS ------------

One way to prove it once and for all would be to try to deflect the
beam with a magnet. Electrons would be deflected, x-rays would not.

Sound reasonable?

Bill, W6WRT

I use HN connectors for high voltage and use RG213 as a conductor. the chassis side I found a mate with a long leakage path. wa1gfz

pentalab wrote:

On Sep 24, 2006, at 10:25 AM, Bill Turner wrote:

ORIGINAL MESSAGE:

On Sun, 24 Sep 2006 10:12:39 -0700, R L Measures <r@...> wrote:

I have seen this on 807s running at 750v with this glow on Tx. Soft
X-rays are more like >10,000v.
As I see it, the effect is caused by electrons from the cathode
missing the anode, striking the glass, and bumping electrons in the
fluxing agent up an a higher orbit When the electrons slow down they
fall back to their normal orbit and emit visible photons.

------------ REPLY FOLLOWS ------------

Wouldn't electrons which "miss" the anode be immediately attracted
back to the outside of the anode? Why would they continue out to the
glass instead of circling back?

They can't reverse direction quick enough?

Some interesting physics here.

Bill, W6WRT



Yahoo! Groups Links

R L MEASURES, AG6K. 805-386-3734
r@...

--- In ham_amplifiers@..., R L Measures <r@...> wrote:

On Sep 24, 2006, at 8:40 AM, Bill Turner wrote:

ORIGINAL MESSAGE:

On Sun, 24 Sep 2006 12:05:38 -0000, "pentalab" <jim.thomson@...>
wrote:

### Are u talking about 3-500Z's and 4-1000's ???? [glass
tubes] I have had new 4-1000's that glowed blue. It was
not gas either.... it was an anomoly/defect in the glass....per
Eimac. The glass would glow blue.... only when drive applied.

------------ REPLY FOLLOWS ------------

I don't think this is a defect. Many tubes show a fluorescence on

the

inside of the glass when operating. I was told it was "soft" x-

rays

caused by electrons impacting the anode and then striking the

glass.

I have seen this on 807s running at 750v with this glow on Tx. Soft

I've seen this in sweep tubes also many times. The glass had a blue
glow in places where there were holes open in the anode. I think Rich
is correct on this that some electrons escape, and strike the glass.
However, if the electron is out there at the glass, how does it get
replaced back into the cathode?

X-rays are more like >10,000v.
As I see it, the effect is caused by electrons from the cathode
missing the anode, striking the glass, and bumping electrons in the
fluxing agent up an a higher orbit When the electrons slow down they

fall back to their normal orbit and emit visible photons.

Whether that is the real cause or not, I've seen it many times.
Nothing to worry about.

The tubes that do not fluoresce probably have a different mix of
compounds or elements in the glass.

Agreed. There are several different fluxing agents used in glass
recipes.

This should not be confused with a blue glow between the elements.
That is gas and is something to worry about.

What's to worry about?, it's done.

Bill, W6WRT



Yahoo! Groups Links

R L MEASURES, AG6K. 805-386-3734
r@...

Best,

Will

Gettering of those and similar tubes is done by the anode coating.
One reason they have to be driven red, which is about 800°C

73
Peter

________________________________

Subject: [ham_amplifiers] Re: How to Getter a 3CX-3000A7 / 6000 / 10,000 ,
etc !

Did you ever get to speak to anyone at Eimac about where the getters
were at in a 3-500Z? That's a question I'd say a few of us would like
to find out about as I think there is some erroneous info floating
around on the net about it. One said it was the anode itself, but it
doesn't get hot enough in my opinion to do it, and would actually have
relaeased hydrogen gas if, a certain gettering material were applied
to it. Any thoughts on this?

Jim,

Did you ever get to speak to anyone at Eimac about where the getters
were at in a 3-500Z? That's a question I'd say a few of us would like
to find out about as I think there is some erroneous info floating
around on the net about it. One said it was the anode itself, but it
doesn't get hot enough in my opinion to do it, and would actually have
relaeased hydrogen gas if, a certain gettering material were applied
to it. Any thoughts on this?

73,

Will

--- In ham_amplifiers@..., "pentalab" <jim.thomson@...>
wrote:

--- In ham_amplifiers@..., R L Measures <r@...> wrote:

Do getters stop working when the HV is applied? ... when the

drive is applied? ... or when both are applied?

### getter's [per Eimac and Svetlana] are ALWAYS working...
as long as the fil is lit. HV + drive are not part of the
overall process.

ANY and
all residual gas and junk is absorbed by the getter's... and
you will never get any surprises... like any arcing from
anode to the grounded grid !!

I've fired up several gassy tubes, the insides glowed blue, but

none of them arced to the grid.

### Are u talking about 3-500Z's and 4-1000's ???? [glass
tubes] I have had new 4-1000's that glowed blue. It was
not gas either.... it was an anomoly/defect in the glass....per
Eimac. The glass would glow blue.... only when drive applied.

### Then I have also seen 4-1000's that glowed blue INSIDE the
anode/screen/grid compartment..... dunno if that was with drive
applied or not...... that was too long ago.

### With a big ceramic triode/terode.... I highly suspect... If
it's gassy... and BOTH HV and drive are applied.... arcs MIGHT
occur between anode to screen... or anode to grid.

### If the vac isn't good and hard in the 1st place.... that
could easily create even more problems.

### I had several 4-1000's yrs ago... that looked like a smoke
bomb going off inside.... when the fil V was applied!! They had
either a lousy vac.... or..'had gone to air'.

### did u ever see a blue glow inside the ceramic portion of a
metal tube ?? Kinda tough to see..with the chimney on.

### All I was trying to get at was.... if 16 guys say to use
48 hrs to getter a new/rebuilt tube.... and anything less is
gonna be a problem... cuz they have tried many diff time
frames... who am I to argue?

### Svetlana claims their tubes are proccesed at a higher temp
than Eimac [during the construction of the tube]... one would
think the Svetlana tubes would have less of a 'gas' problem
than an Eimac ?

### The Svetlana tubes all use a 'spiral mesh fil' and
where all the mesh criss crosses... they are welded. ... so
u don't wanna slam the fil V on.. it can buckle the mesh fil
sideways..esp with over rated fil xfmrs [eg: I use a 80 A
rated fil xfmr on my 50 A rated 3000A7]......... another reason
to step start em.

## I don't have the time or patience to inadvertantly destroy
expensive new/rebuilt tubes.

Later... Jim VE7RF

...

R L MEASURES, AG6K. 805-386-3734
r@...

Hi Jim,

I understand that tube life is dependend on their vacuum and on the emission
from the cathode such that material of it disappears until worn, and then
the tube is probably send in for a new coating.
How does ?the clock tick? when just the heater is lit and no current flows?
73, Peter


________________________________

From: ham_amplifiers@... [mailto:ham_amplifiers@...]
On Behalf Of pentalab

Always remember.... when the fil is lit...'the clock is ticking'.

Bill Turner wrote:
<snip>

Wouldn't electrons which "miss" the anode be immediately attracted
back to the outside of the anode? Why would they continue out to the
glass instead of circling back?
Some interesting physics here. Bill, W6WRT

They're moving too fast to circle back in that distance.

We had a discussion about fluorescence in ceramic tubes some time back and I posted a few pictures of GS-35B's glowing in the dark <>. The best explanation was electron bombardment as opposed to soft X-rays. Just not enough voltage to accelerate the electrons enough to generate the X-rays. Most of the pictures were taken with less than 2500 Volts on the anode.

73, Tony W4ZT

ORIGINAL MESSAGE:

On Sun, 24 Sep 2006 10:12:39 -0700, R L Measures <r@...> wrote:

I have seen this on 807s running at 750v with this glow on Tx. Soft
X-rays are more like >10,000v.
As I see it, the effect is caused by electrons from the cathode
missing the anode, striking the glass, and bumping electrons in the
fluxing agent up an a higher orbit When the electrons slow down they
fall back to their normal orbit and emit visible photons.

------------ REPLY FOLLOWS ------------

Wouldn't electrons which "miss" the anode be immediately attracted
back to the outside of the anode? Why would they continue out to the
glass instead of circling back?

Some interesting physics here.

Bill, W6WRT

On Sep 24, 2006, at 8:40 AM, Bill Turner wrote:

ORIGINAL MESSAGE:

On Sun, 24 Sep 2006 12:05:38 -0000, "pentalab" <jim.thomson@...>
wrote:

### Are u talking about 3-500Z's and 4-1000's ???? [glass
tubes] I have had new 4-1000's that glowed blue. It was
not gas either.... it was an anomoly/defect in the glass....per
Eimac. The glass would glow blue.... only when drive applied.

------------ REPLY FOLLOWS ------------

I don't think this is a defect. Many tubes show a fluorescence on the
inside of the glass when operating. I was told it was "soft" x-rays
caused by electrons impacting the anode and then striking the glass.

I have seen this on 807s running at 750v with this glow on Tx. Soft X-rays are more like >10,000v.
As I see it, the effect is caused by electrons from the cathode missing the anode, striking the glass, and bumping electrons in the fluxing agent up an a higher orbit When the electrons slow down they fall back to their normal orbit and emit visible photons.

Whether that is the real cause or not, I've seen it many times.
Nothing to worry about.

The tubes that do not fluoresce probably have a different mix of
compounds or elements in the glass.

Agreed. There are several different fluxing agents used in glass recipes.

This should not be confused with a blue glow between the elements.
That is gas and is something to worry about.

What's to worry about?, it's done.

Bill, W6WRT



Yahoo! Groups Links

R L MEASURES, AG6K. 805-386-3734
r@...

On Sep 24, 2006, at 5:05 AM, pentalab wrote:

--- In ham_amplifiers@..., R L Measures <r@...> wrote:

Do getters stop working when the HV is applied? ... when the

drive is applied? ... or when both are applied?

### getter's [per Eimac and Svetlana] are ALWAYS working...
as long as the fil is lit. HV + drive are not part of the
overall process.

If this is the case, why not use the tubes as they are being gettered? This has always been the way that I have done it.

ANY and
all residual gas and junk is absorbed by the getter's... and
you will never get any surprises... like any arcing from
anode to the grounded grid !!

I've fired up several gassy tubes, the insides glowed blue, but
none of them arced to the grid.

### Are u talking about 3-500Z's and 4-1000's ???? [glass
tubes]

Yes

I have had new 4-1000's that glowed blue. It was
not gas either.... it was an anomoly/defect in the glass....per
Eimac. The glass would glow blue.... only when drive applied.

I too have see fluorescing glass, and it's definitely different than gas fluorescing.

### Then I have also seen 4-1000's that glowed blue INSIDE the
anode/screen/grid compartment..... dunno if that was with drive
applied or not...... that was too long ago.

### With a big ceramic triode/terode.... I highly suspect... If
it's gassy... and BOTH HV and drive are applied.... arcs MIGHT
occur between anode to screen... or anode to grid.

Possible, but I have never found an arc mark in a kaput autopsied tube.

### If the vac isn't good and hard in the 1st place.... that
could easily create even more problems.

Indicated by a blue glow inside the vacuum.

### I had several 4-1000's yrs ago... that looked like a smoke
bomb going off inside.... when the fil V was applied!!

Leaky seal. I've seen that one. I saved a 4E27 with gas to light up for the young whippersnappers.

They had
either a lousy vac.... or..'had gone to air'.

### did u ever see a blue glow inside the ceramic portion of a
metal tube ??

No, but the chimney on my 8170 amplifier was opaque.

Kinda tough to see..with the chimney on.

A lexan window would be easy to retrofit in a fiberglas-epoxy chimney.

### All I was trying to get at was.... if 16 guys say to use
48 hrs to getter a new/rebuilt tube.... and anything less is
gonna be a problem... cuz they have tried many diff time
frames... who am I to argue?

I have run into a number of amateur radio dudes who advise something that sounds semi-plausible, but instead of being based in science, it turns out to be an artifice for promoting his guru status by giving the appearance of having esoteric knowledge.

### Svetlana claims their tubes are proccesed at a higher temp
than Eimac [during the construction of the tube]... one would
think the Svetlana tubes would have less of a 'gas' problem
than an Eimac ?

Seal integrity and time spent pumping them down would seem to be most important.

### The Svetlana tubes all use a 'spiral mesh fil' and
where all the mesh criss crosses... they are welded. ... so
u don't wanna slam the fil V on.. it can buckle the mesh fil
sideways..esp with over rated fil xfmrs [eg: I use a 80 A
rated fil xfmr on my 50 A rated 3000A7]......... another reason
to step start em.

I use step-starting because it's easier on Everything - and 1 to 2 seconds is no biggie.

## I don't have the time or patience to inadvertantly destroy
expensive new/rebuilt tubes.

I have probably never run filaments for more than a minute before firing up a new 3-500Z or 8170.

Later... Jim VE7RF

later

...

R L MEASURES, AG6K. 805-386-3734
r@...

Yahoo! Groups Links

R L MEASURES, AG6K. 805-386-3734
r@...

ORIGINAL MESSAGE:

On Sun, 24 Sep 2006 08:18:57 -0000, "pentalab" <jim.thomson@...>
wrote:

I have been using Belden 10 KV test prod wire for the last
several years.

------------ REPLY FOLLOWS ------------

A good source of HV wire is West Marine. They have a 40 kv marine
grade wire. They sell it by the foot so you buy only what you need.
Large center conductor, very strong, reasonably flexible. Working
great here.

Bill, W6WRT

ORIGINAL MESSAGE:

On Sun, 24 Sep 2006 12:05:38 -0000, "pentalab" <jim.thomson@...>
wrote:

### Are u talking about 3-500Z's and 4-1000's ???? [glass
tubes] I have had new 4-1000's that glowed blue. It was
not gas either.... it was an anomoly/defect in the glass....per
Eimac. The glass would glow blue.... only when drive applied.

------------ REPLY FOLLOWS ------------

I don't think this is a defect. Many tubes show a fluorescence on the
inside of the glass when operating. I was told it was "soft" x-rays
caused by electrons impacting the anode and then striking the glass.
Whether that is the real cause or not, I've seen it many times.
Nothing to worry about.

The tubes that do not fluoresce probably have a different mix of
compounds or elements in the glass.

This should not be confused with a blue glow between the elements.
That is gas and is something to worry about.

Bill, W6WRT

Am 24.09.2006 um 10:47 schrieb pentalab:

--- In ham_amplifiers@..., Frank Goenninger <frgo@...>
wrote:

Am 24.09.2006 um 09:52 schrieb pentalab:

### Millens are fine up to 5 kv. For the 5-10 kv stuff....
I'm going to go to a better connector.

Which ones would these be?

### Probably either Alden or Kings or Rowe. All 3 x brands
have good connectors rated at 25 kv and more. These red/black
Millen's are just too mickey mouse. The Phenolic material
will eventually absorb moisture.

### Perhaps a google on... " High Voltage connector's" will turn
up some answers........ it usually does.

;-) It did help. All of them say "I'm the best". That's why I kept asking here. Tnx for sharing your experience!

73, Frank DG1SBG

--- In ham_amplifiers@..., R L Measures <r@...> wrote:

Do getters stop working when the HV is applied? ... when the

drive is applied? ... or when both are applied?

### getter's [per Eimac and Svetlana] are ALWAYS working...
as long as the fil is lit. HV + drive are not part of the
overall process.

ANY and
all residual gas and junk is absorbed by the getter's... and
you will never get any surprises... like any arcing from
anode to the grounded grid !!

I've fired up several gassy tubes, the insides glowed blue, but

none of them arced to the grid.

### Are u talking about 3-500Z's and 4-1000's ???? [glass
tubes] I have had new 4-1000's that glowed blue. It was
not gas either.... it was an anomoly/defect in the glass....per
Eimac. The glass would glow blue.... only when drive applied.

### Then I have also seen 4-1000's that glowed blue INSIDE the
anode/screen/grid compartment..... dunno if that was with drive
applied or not...... that was too long ago.

### With a big ceramic triode/terode.... I highly suspect... If
it's gassy... and BOTH HV and drive are applied.... arcs MIGHT
occur between anode to screen... or anode to grid.

### If the vac isn't good and hard in the 1st place.... that
could easily create even more problems.

### I had several 4-1000's yrs ago... that looked like a smoke
bomb going off inside.... when the fil V was applied!! They had
either a lousy vac.... or..'had gone to air'.

### did u ever see a blue glow inside the ceramic portion of a
metal tube ?? Kinda tough to see..with the chimney on.

### All I was trying to get at was.... if 16 guys say to use
48 hrs to getter a new/rebuilt tube.... and anything less is
gonna be a problem... cuz they have tried many diff time
frames... who am I to argue?

### Svetlana claims their tubes are proccesed at a higher temp
than Eimac [during the construction of the tube]... one would
think the Svetlana tubes would have less of a 'gas' problem
than an Eimac ?

### The Svetlana tubes all use a 'spiral mesh fil' and
where all the mesh criss crosses... they are welded. ... so
u don't wanna slam the fil V on.. it can buckle the mesh fil
sideways..esp with over rated fil xfmrs [eg: I use a 80 A
rated fil xfmr on my 50 A rated 3000A7]......... another reason
to step start em.

## I don't have the time or patience to inadvertantly destroy
expensive new/rebuilt tubes.

Later... Jim VE7RF

...

R L MEASURES, AG6K. 805-386-3734
r@...

开云体育

--- In ham_amplifiers@..., PA3DUV <pa3duv@...> wrote:

Also the SHV will accept RG8U coax only.

### If that's the case... then it will also accept Teflon RG-
393 coax.... which is a bit smaller OD than 8-U/213-U [.390"
OD for 393 coax.... vs .405" OD for 8-U /213-U
Jim VE7RF

Actually the H+S SHV is the same type as the Kings HT connectors,

a bit flimsy.

I just browsed the site. (Thanks

Greg!)

These look better to me, are mechanical sound, accept 11/12 mm

coax as well and can be supplied with nice bend restrictors.

Cheers, Dick
PA3DUV

Gents

After reading the material from Both Eimac and Svetlana...
[extending tube life via proper fil v management] a few yrs
back... I thought I would give it a try.

At my former workshop location... the power line regulation was
terrible.... so I researched SOLA constant volatge xfmr's...
and other ferroresonant xfmrs.

I managed to obtain a used SOLA 750 VA unit that's kinda
unique. It was not only regulated.... it was also 'harmonically
neutralized'.[has a pair of small oil caps in it]. It also had
3 sets of primary taps.... for 120 vac... 208 vac... and 240
vac......slick. Good so far.

The output of this thing is a constant 236/118 Vac [new ones are
all 240 vac, mine's an old one]. It's 236 vac output... with a
center tapped sec. The manual stated.. " all 3 x loads... leg
1 to neutral... leg 2 to neutral... and across the 2 x hot
legs... when added up.... can't exceed 750 VA. Good so far.

These things will handle a HUGE +/- voltage range on any of
the 3 pri taps.... and still output a constant 236/118 vac.

I tested it by wiring the pri for the 120 vac tap.... then
used a 0-132 vac variac... with the variac's OUTPUT feeding the
INPUT of the SOLA. With the variac set below 120 vac... the
sola's output V was slightly higher than 236/118 vac. With
the variac set HIGHER than 120 Vac..... the OUTPUT of the sola
dropped a tiny bit below 236/118 vac.

Even with the variac set as low as 50 vac... the sola still put
out 238 vac.

The constant output of the Sola is normally fed to the INPUT of a
small 5 A variac [240/120, depending on the fil xfmr used]. The
now CONSTANT Voltage output of the variac, is of course fed to
the primary of the Dahl fil xfmr!

Install a new 115 vac HOUR meter between one hot leg of SOLA
and center tap of the Sola. [output of sola]

I used either 1 or 2.5 mh rf chokes [100ma rated is plenty] ,
and placed one per leg.. at the socket. Other ends are fed to
both a 0-10 vac panel meter and a pair of banana jacks [stuff
ur Fluke 87-A true rms meter in there]. Both the panel meter
and the banana jacks have a 1 k resistor in each leg + .01 uf
bypass caps. The resistor's will limit the current to a safe
level if anything shorts out... and won't affect ur reading's.

We also use a simple DPDT toggle.... to switch the metering
from the socket.. to the Fil xfmr Secondary. Reason is... so
we can measure the V drop in ALL the wiring, lugs, any cross
connects.. and the 80 A bifilar choke . You will typ see
between .3v and .4v for the v drop. Most of that is coming
from the bifilar. The point here is.. to get say 7.0 v at
the socket.... ur gonna need 7.3 to 7.4 v at the xfmr
secondary.

Dahl fil xfmrs [and all other's] rate their fil xfmrs UNDER
FULL LOAD. Typ no load on a fil xfmr is usually 10% higher.

Factor this in, in any GG linear... that uses a high current
Bifilar.

Now Rich will tell you to float the xfmr.. and use a tiny
bifilar in the 240 vac primary... and this works good...BUT...
the floated xfmr MUST be installed in the RF deck.. below the
chassis. That just adds another 23 lbs to the RF deck...
tipping the scale... and making it very difficult for one person to
get the RF deck in and out of the rack.

I always use a high current Bifilar [80 A or less]... and mount
the 66lb Sola, 5 A Variac, 23 lb fil Xfmr.... in the next
shelf below the RF deck. Short, flexible heavy gauge pair of
wires interconnect the two. [typ 2 ga]

I also install a 25 ohm 100-150 w wire wound /metal finned
resistor in one leg of the Dahl fil xfmr primary.... and also a
0-30 second... 8 pin octal time delay relay is used to shunt out
this same resistor [ after 5-10 seconds] With a Dahl 240 vac
primary on the fil xfmr.... it works out that the Fil V is
exactly 75% of rated V ..[until the 25 ohm resistor is shunted]

I include the fil step start so I can leave the variac alone.
Also... in the event of a commercial AC power failure... the step
start sequence just sequences again [when power comes back on].

If You are gonna use the variac as a 'step start'.. u have to
remember to turn it DOWN after you shut off the amp. [also
during a power failure]

Now we can finally 'manage the fil V for extended tube life'.

Both Svetlana and Eimac state that on these big metal tubes...
[THORIATED TUNGSTEN FILS ONLY].... that fil emmission INCREASES
in the 1st 150-200 hrs !! [new or rebuilt tube] .

After gettering the tube for the 1st 48 hrs [at rated fil V
measured at the socket, NO HV]... one can now fire up the
HV ..and apply drive.

Eimac and Svetlana state.. after 150-200 hrs [I use the 200 hr
number], fil V can be REDUCED.

Here's what I did. After the 200 hrs is up on the hr meter......
while pulse tuning the linear [amp running full bore, perhaps a
BIT more than full bore] .. reduce the fil voltage, by turning
down the variac... till PEP power output JUST starts to DROP !!
THEN increase it a tiny bit... like .1 to .2 V.

Now my buddy with the new Svetlana 3CX-6000A7 has just done
this... and his fil V [measured at the socket] is now sitting
at 6.0 volts !! [The rated fil V for a 6000 is 7.0 volts]

Fil V is checked once in a while... and the idea here is... IF
you see that the emmision has dropped off at all... you increase
the fil V until power output is back up.

IE: tweak the variac, until PEP power output is just on
the 'hairy edge'... then increase the fil v another .1 to .2 v.

Follow the above procedure... and you will easily get 35,000
hours from the tube !! [4 yrs in a 24/7 situation]. In a 'typ'
6 hrs per day scenario... that equates to 16 yrs !!!!

Once the emmision is down, such that you have to increase the fil
V ABOVE the tube's nominal rated fil V..... then you have 2 x
option's. Either crank the variac UP, so fil V is now above
rated fil V [never go more than + 5%] OR send it back for a
rebuild.

Both Eimac and Svetlana say to just send it back for a
rebuild. I'm inclined to partially agree.. since once you have
the fil V ABOVE rated fil V.... tube life will drop... FAST.

As you can see, I and other's..take this .. 'filament
management for longer tube life' very seriously.... ditto with
the fil step start / commercial power failure scenario.

One other important thing...when finished for the night [or
day]... after turning OFF the fil... ALWAYS let the blower run
for a good 10-20 mins. We use a blower.. 'over run'
circuit.....consists of yet another Timer module... "delay on
OFF" type. These are usually 11 pin octal types.


Always remember.... when the fil is lit...'the clock is ticking'.

Later........ Jim VE7RF