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6AU6 Plate to Grid short
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febru...@nonewhere.com
Nov 29, 2016, 7:11:58 AM11/29/16
to
My old tube tester confirmed a short in this 6AU6 tube, which explains
why a resistor fried on it's socket. I know replacement is the best
solution, but old tubes are getting hard to find. I always figured
shorts inside tubes occur because the parts inside are loose. Is it
possible to drill into the glass, and use a pin to align the parts so
they are not shorted, then shoot some epoxy inside to keep these parts
solid, so they cant touch anymore?
Yes, I know they need a vacuum, so I'll have to use a vacuum cleaner to
suck out the air, then epoxy the hole shut.
why a resistor fried on it's socket. I know replacement is the best
solution, but old tubes are getting hard to find. I always figured
shorts inside tubes occur because the parts inside are loose. Is it
possible to drill into the glass, and use a pin to align the parts so
they are not shorted, then shoot some epoxy inside to keep these parts
solid, so they cant touch anymore?
Yes, I know they need a vacuum, so I'll have to use a vacuum cleaner to
suck out the air, then epoxy the hole shut.
dansabr...@yahoo.com
Nov 29, 2016, 7:18:54 AM11/29/16
to
Dan
N_Cook
Nov 29, 2016, 7:42:08 AM11/29/16
to
C/H "shorts" you can often get a bit more life without "bacon & eggs" by
upping the heater volts on the tester for a few seconds, to compress the
oxide? back a bit. G/A shorts presumably due to thermal bending/failed
spot weld unlikely. If I was going to give it a go I'd try very high
magnetic field and high current through the G/A contact and arrange for
the magnetic force to hopefully bend the relevant bit farther away. So
shit or bust, make a G/A spot-weld or spring apart.
If a structural suport failure , reorientate the valve perhaps
Phil Hobbs
Nov 29, 2016, 9:47:16 AM11/29/16
to
pressure--it's used in photomultipliers, and its migration is
inconveniently fast even at 20C.
Cheers
Phil Hobbs
--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC
Optics, Electro-optics, Photonics, Analog Electronics
160 North State Road #203
Briarcliff Manor NY 10510
hobbs at electrooptical dot net
http://electrooptical.net
Phil Hobbs
Nov 29, 2016, 9:49:56 AM11/29/16
to
Factory that explains a lot of stuff like that:
https://www.youtube.com/watch?v=GDvF89Bh27Y
Cheers
Phil Hobbs
ohg...@gmail.com
Nov 29, 2016, 10:12:28 AM11/29/16
to
On Tuesday, November 29, 2016 at 7:11:58 AM UTC-5, febru...@nonewhere.com wrote:
http://www.ebay.com/itm/Philco-6AU6A-Electronic-Vacuum-Tube-Made-In-USA-NOS-/262736599165?hash=item3d2c52587d:g:53YAAOSwal5YEXx7
pf...@aol.com
Nov 29, 2016, 10:18:31 AM11/29/16
to
On Tuesday, November 29, 2016 at 7:11:58 AM UTC-5, febru...@nonewhere.com wrote:
>>MUCH Snippage<<
a) Nothing you have 'at home' will create sufficient vacuum for what you propose.
b) Even if you have a source of Barium to replace the original 'getter', you would have to remove the envelope entirely to install it.
c) 6AU6 tubes are common, very common. I have at least a dozen in my tube stash. Our club sells them tested and good in the $2 range.
d) And the chances are very likely unless you are a micro-surgeon, that you will screw something up in the process anyway.
Peter Wieck
Melrose Park, PA
tom
Nov 29, 2016, 12:30:24 PM11/29/16
to
<febru...@nonewhere.com> wrote in message
news:93rq3c5m16ell224c...@4ax.com...
Please try to up your game.
Ralph Mowery
Nov 29, 2016, 1:05:43 PM11/29/16
to
In article <o1kdt0$h08$1...@dont-email.me>, tmille...@verizon.net
says...
Iknow this is trolling, but on youtube I ran across a person that was
building small tubes such as this at his house. Very interisting to
watch him do it.
Long time ago and I don't recall the title or where to find it.
says...
building small tubes such as this at his house. Very interisting to
watch him do it.
Long time ago and I don't recall the title or where to find it.
Michael Black
Nov 29, 2016, 2:26:48 PM11/29/16
to
But in 1964 or 65 there was an article in QST about an Argentinian who wa
making tubes. He was mostly interested in making his own power tubes for
transmitters, so his own design rather than copying well known tubes.
They talk about it in the areas where antique radios are discussed,
there's a certain plateau one has to reach and most aren't up there yet.
What I wonder is if it was "common" in the early days of tubes. People
made all kinds of things, I've read that they'd get some quartz and make
their own crystals even and certainly people made their own paper
capacitors in the early days, so making a tube might not be out of the
norm, so long as someone had the resources. It might perhaps have been
more "common" back then, since tubes were still new, but perhaps not. But
it would be interesting to see if there were articles about making your
own tubes back then.
Getting enough vacuum seems to be a common issue, at least once you have
some success as a glass blower. I haven't seen much about whether people
are making triodes or anything more complicated.
Michael
Andy Burns
Nov 29, 2016, 2:32:33 PM11/29/16
to
Michael Black wrote:
> Ralph Mowery wrote:
>
>> I know this is trolling, but on youtube I ran across a person that was
>> building small tubes
>
<https://youtu.be/EzyXMEpq4qw>
> People made all kinds of things
There was a more recent one of someone making larger nixie tubes than
the NOS ones
<https://youtu.be/wxL4ElboiuA>
> Ralph Mowery wrote:
>
>> I know this is trolling, but on youtube I ran across a person that was
>> building small tubes
>
> There was one from Europe a few years ago that got a lot of travel.
You're probably remembering this one
<https://youtu.be/EzyXMEpq4qw>
> People made all kinds of things
the NOS ones
<https://youtu.be/wxL4ElboiuA>
Look165
Nov 29, 2016, 2:35:46 PM11/29/16
to
A great number of sites on the Net provide old tubes.
There also exist tube regenerators which can remove short-circuits.
It also works for old CRT tubes.
But it is rather expensive and you have to find a shop which owns one.
febru...@nonewhere.com a écrit :
There also exist tube regenerators which can remove short-circuits.
It also works for old CRT tubes.
But it is rather expensive and you have to find a shop which owns one.
febru...@nonewhere.com a écrit :
analogdial
Nov 29, 2016, 5:22:30 PM11/29/16
to
Still won't work. You better come up with a plan for fixing the
resistor, too.
resistor, too.
analogdial
Nov 29, 2016, 5:38:17 PM11/29/16
to
Michael Black wrote:
> There was one from Europe a few years ago that got a lot of travel.
>
> But in 1964 or 65 there was an article in QST about an Argentinian who wa
> making tubes. He was mostly interested in making his own power tubes for
> transmitters, so his own design rather than copying well known tubes.
>
> They talk about it in the areas where antique radios are discussed,
> there's a certain plateau one has to reach and most aren't up there yet.
>
> What I wonder is if it was "common" in the early days of tubes. People
> made all kinds of things, I've read that they'd get some quartz and make
> their own crystals even and certainly people made their own paper
> capacitors in the early days, so making a tube might not be out of the
> norm, so long as someone had the resources. It might perhaps have been
> more "common" back then, since tubes were still new, but perhaps not. But
> it would be interesting to see if there were articles about making your
> own tubes back then.
>
> Getting enough vacuum seems to be a common issue, at least once you have
> some success as a glass blower. I haven't seen much about whether people
> are making triodes or anything more complicated.
>
> Michael
There was alot of tube bootlegging going on in the early 20s. I'm think
> There was one from Europe a few years ago that got a lot of travel.
>
> But in 1964 or 65 there was an article in QST about an Argentinian who wa
> making tubes. He was mostly interested in making his own power tubes for
> transmitters, so his own design rather than copying well known tubes.
>
> They talk about it in the areas where antique radios are discussed,
> there's a certain plateau one has to reach and most aren't up there yet.
>
> What I wonder is if it was "common" in the early days of tubes. People
> made all kinds of things, I've read that they'd get some quartz and make
> their own crystals even and certainly people made their own paper
> capacitors in the early days, so making a tube might not be out of the
> norm, so long as someone had the resources. It might perhaps have been
> more "common" back then, since tubes were still new, but perhaps not. But
> it would be interesting to see if there were articles about making your
> own tubes back then.
>
> Getting enough vacuum seems to be a common issue, at least once you have
> some success as a glass blower. I haven't seen much about whether people
> are making triodes or anything more complicated.
>
> Michael
a guy with the specialized equipment to make one tube would be strongly
tempted to make a dozen or hire people and make hundreds or more.
jurb...@gmail.com
Nov 29, 2016, 9:55:41 PM11/29/16
to
>"Iknow this is trolling, but..."
I am not so sure. There are alot of people, especially in the US, who think you can DIY things you simply can't. It is a matter of knowing the process. At this point I wonder if tubes like a 6AU6 are bombarded like CRTs were.
At one point I thought about trying to build an EMPG but after some research (not posting on a forum) found out it is just about impossible without alot of money and resources. I have come up with alot of ideas that simply were not practical, and the ones that were were either unsaleable or already done and at the very least unpatentable.
Also, some people have no idea how to think things through. Even with an adequate vacuum pump, just how do you get the epoxy on there ? Tubes, before final manufacturing processes have a tube through which the vacuum is pulled ad then that is heated right near the seat of the socket, or other end and in the atmosphere the glass tubing collapses and then you cut it off. I am not sure when the getter is applied.
And the OP's assumption that one of the suspension components broke is a bit off as well. The 6AU6 is a pentode right ? Does it have the suppressor grid internally tied to the cathode ? (most do) If so the short is more likely caused by one of those fine wires simply breaking. They are held in place by mica sheets so any misalignment could only come from traumatic mechanical shock.
now if he has a G1 to plate short then the trauma must have been vertical and just made the whole thing shift down and cause the wires at the bottom going to the actual pins short out. Otherwise the short would read cathode to G2, not plate. Well not necessarily.
An excellent exercise in futility for a Tuesday night. Get off the four bucks and buy the tube and replace the resistor.
I am not so sure. There are alot of people, especially in the US, who think you can DIY things you simply can't. It is a matter of knowing the process. At this point I wonder if tubes like a 6AU6 are bombarded like CRTs were.
At one point I thought about trying to build an EMPG but after some research (not posting on a forum) found out it is just about impossible without alot of money and resources. I have come up with alot of ideas that simply were not practical, and the ones that were were either unsaleable or already done and at the very least unpatentable.
Also, some people have no idea how to think things through. Even with an adequate vacuum pump, just how do you get the epoxy on there ? Tubes, before final manufacturing processes have a tube through which the vacuum is pulled ad then that is heated right near the seat of the socket, or other end and in the atmosphere the glass tubing collapses and then you cut it off. I am not sure when the getter is applied.
And the OP's assumption that one of the suspension components broke is a bit off as well. The 6AU6 is a pentode right ? Does it have the suppressor grid internally tied to the cathode ? (most do) If so the short is more likely caused by one of those fine wires simply breaking. They are held in place by mica sheets so any misalignment could only come from traumatic mechanical shock.
now if he has a G1 to plate short then the trauma must have been vertical and just made the whole thing shift down and cause the wires at the bottom going to the actual pins short out. Otherwise the short would read cathode to G2, not plate. Well not necessarily.
An excellent exercise in futility for a Tuesday night. Get off the four bucks and buy the tube and replace the resistor.
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