UK Vintage Radio Repair and Restoration Powered By Google Custom Search Vintage Radio Service Data

Go Back   UK Vintage Radio Repair and Restoration Discussion Forum > General Vintage Technology > General Vintage Technology Discussions

Notices

General Vintage Technology Discussions For general discussions about vintage radio and other vintage electronics etc.

Reply
 
Thread Tools
Old 14th Jan 2020, 10:52 pm   #1
Tinker1966
Triode
 
Join Date: Nov 2014
Location: Leominster, Herefordshire, UK.
Posts: 12
Default Valve testing a 4212

I have recently acquired a very large valve - a 4212H, I believe.
Is it possible to test one of these huge valves ?
It is undoubtedly beyond me !
I have ascertained the filament has continuity and thats me done!
Is this a service that is provided by anyone ?
Many thanks
Tinker1966 is offline   Reply With Quote
Old 14th Jan 2020, 11:59 pm   #2
AC/HL
Moderator
 
AC/HL's Avatar
 
Join Date: Nov 2003
Location: Heckmondwike, West Yorkshire, UK.
Posts: 7,753
Default Re: Valve testing a 4212

One of these: https://vintage-radio.net/forum/showthread.php?t=40716
__________________
Bill, BVWS member
AC/HL is offline   Reply With Quote
Old 15th Jan 2020, 8:52 am   #3
Ed_Dinning
Dekatron
 
Join Date: Jan 2004
Location: Newcastle upon Tyne, Tyne & Wear, UK.
Posts: 5,760
Default Re: Valve testing a 4212

Hi Tinker, you should be able to run the filament supply up and then connect a voltmeter between cathode and grid. If the valve has emission you should get a small voltage reading.
Then you can think about other power supplies to try it in anger.

Ed
Ed_Dinning is offline   Reply With Quote
Old 15th Jan 2020, 9:04 am   #4
Tinker1966
Triode
 
Join Date: Nov 2014
Location: Leominster, Herefordshire, UK.
Posts: 12
Default Re: Valve testing a 4212

Yes - thats the one.

Well - I have a voltmeter so thats a step in the right direction - but as to connecting up the filament I would have no idea what kind of voltage to apply and would be terrified of doing the wrong thing - I am led to believe this valve has a fair value, so it might well end upon ebay...
Tinker1966 is offline   Reply With Quote
Old 15th Jan 2020, 4:05 pm   #5
Tinker1966
Triode
 
Join Date: Nov 2014
Location: Leominster, Herefordshire, UK.
Posts: 12
Default Re: Valve testing a 4212

Quote:
Originally Posted by Ed_Dinning View Post
Hi Tinker, you should be able to run the filament supply up and then connect a voltmeter between cathode and grid. If the valve has emission you should get a small voltage reading.
Then you can think about other power supplies to try it in anger.

Ed
So - reading the link above it seems the filament runs at about 14v ?
If I apply that to the filament with a variac and connect a voltmeter to the other two pins I should get a reading .....
Am I on the right track ? I shan't do anything just yet .......!!
Thanks for the help
Tinker1966 is offline   Reply With Quote
Old 15th Jan 2020, 5:10 pm   #6
David Simpson
Nonode
 
Join Date: Mar 2008
Location: Aberdeen, UK.
Posts: 2,040
Default Re: Valve testing a 4212

There was a similar thread to this a few weeks before Christmas. See "Search". Also, I actually tested one a couple or so years ago, using a bespoke DC Rig, plus produced a Ia/Vg Graph which I could compare with an actual STC graph. Sourcing a high current heater voltage is the awkward bit.

Regards, David
David Simpson is offline   Reply With Quote
Old 15th Jan 2020, 8:23 pm   #7
rambo1152
Octode
 
rambo1152's Avatar
 
Join Date: May 2010
Location: Manchester, UK.
Posts: 1,578
Default Re: Valve testing a 4212

Quote:
Originally Posted by David Simpson View Post
Sourcing a high current heater voltage is the awkward bit.

Regards, David
14V @ 6A would be the easy part for me.
__________________
--
Graham.
G3ZVT
rambo1152 is offline   Reply With Quote
Old 15th Jan 2020, 9:10 pm   #8
Station X
Moderator
 
Station X's Avatar
 
Join Date: Jan 2003
Location: Ipswich, Suffolk, IP4, UK.
Posts: 15,426
Default Re: Valve testing a 4212

Car battery? With ln line fuses of course! Not quite 14V, but should suffice for testing.

CB radio PSU?
__________________
Graham. Forum Moderator

Keep the soldering iron hot.
Station X is online now   Reply With Quote
Old 15th Jan 2020, 9:39 pm   #9
Tinker1966
Triode
 
Join Date: Nov 2014
Location: Leominster, Herefordshire, UK.
Posts: 12
Default Re: Valve testing a 4212

Wow thanks Station X -
Car battery - I have several of those hanging about.
So connect that to the filament terminals and measure the other 2 with the voltmeter to see if there's any voltage .....
That's tomorrows project sorted
Tinker1966 is offline   Reply With Quote
Old 15th Jan 2020, 10:14 pm   #10
Station X
Moderator
 
Station X's Avatar
 
Join Date: Jan 2003
Location: Ipswich, Suffolk, IP4, UK.
Posts: 15,426
Default Re: Valve testing a 4212

Don't forget the fuses or you could find yourself doing some involuntary arc welding.

An alternative would be to connect to a car's cigarette lighter/accessory socket which will be fused within the vehicle.
__________________
Graham. Forum Moderator

Keep the soldering iron hot.
Station X is online now   Reply With Quote
Old 15th Jan 2020, 10:57 pm   #11
Tinker1966
Triode
 
Join Date: Nov 2014
Location: Leominster, Herefordshire, UK.
Posts: 12
Default Re: Valve testing a 4212

Ok - fuses at the ready !
I will report back tomorrow
Tinker1966 is offline   Reply With Quote
Old 16th Jan 2020, 10:25 am   #12
rontech
Hexode
 
Join Date: Jun 2017
Location: Southport, Merseyside, UK.
Posts: 280
Default Re: Valve testing a 4212

The National Valve Museum website for 4212 gives a PDF data sheet link
__________________
Time flies like an arrow, fruit flies like a banana
rontech is offline   Reply With Quote
Old 16th Jan 2020, 12:08 pm   #13
David Simpson
Nonode
 
Join Date: Mar 2008
Location: Aberdeen, UK.
Posts: 2,040
Default Re: Valve testing a 4212

Aye Tinker, you'll be needing hefty Va & Vg supplies plus being able to measure in the region of 160mA Ia. Way beyond the VCM's & Valve Testers we all know. Plus you'll need to make a bespoke valve holder with sturdy valve pin connections. Don't be tempted to use cheapo crock-clip leads.
Jesus, was it all that long ago - 7th Oct.2015 was my "Testing the STC 4212D Triode" Thread.
My 4212D drew 6.3A at 14V Vh. And with 500V Va drew 160mA at -5Vg, but I started out gently at -50Vg. If you look at the STC family of Gm curves, you'll see that these fearsome valves were happy working in the 1KV Va region. Running Vh at 12V off a battery might do just to see the thing glow, but 14V would be needed to get comparisons with STC's data.
Caution - if your valve is a decent NOS one, it could be worth a few hundred quid, so don't phook it.

Regards, David
David Simpson is offline   Reply With Quote
Old 16th Jan 2020, 12:25 pm   #14
Station X
Moderator
 
Station X's Avatar
 
Join Date: Jan 2003
Location: Ipswich, Suffolk, IP4, UK.
Posts: 15,426
Default Re: Valve testing a 4212

If this were mine and I wanted to sell it, all I'd do would be to test the heater for continuity and state that it had continuity in my eBay listing or W.H.Y.

That's what I did with a load of 4CX250B's a few years back.
__________________
Graham. Forum Moderator

Keep the soldering iron hot.
Station X is online now   Reply With Quote
Old 16th Jan 2020, 12:56 pm   #15
Tinker1966
Triode
 
Join Date: Nov 2014
Location: Leominster, Herefordshire, UK.
Posts: 12
Default Re: Valve testing a 4212

Thanks everyone for the advice - I have already tested for continuity of the filament and it is good.
I think on balance I shall leave it there and sell it as is.
Tinker1966 is offline   Reply With Quote
Old 16th Jan 2020, 1:03 pm   #16
rambo1152
Octode
 
rambo1152's Avatar
 
Join Date: May 2010
Location: Manchester, UK.
Posts: 1,578
Default Re: Valve testing a 4212

Quote:
Originally Posted by Tinker1966 View Post
Wow thanks Station X -
Car battery - I have several of those hanging about.
So connect that to the filament terminals and measure the other 2 with the voltmeter to see if there's any voltage .....
That's tomorrows project sorted
Not quite, there won't be any voltage, you have to apply some and measure the current.

I'm just wondering how low a voltage you could use, and see some current and diode effect on a multimeter? Would a 9V battery be too low? Would -9v from a second battery be expected to cut the valve off or at least reduce the current?

More a classroom demo than meaningful testing, but it would prove there was some vacuum and emission.
(posts crossed)
__________________
--
Graham.
G3ZVT
rambo1152 is offline   Reply With Quote
Old 16th Jan 2020, 1:30 pm   #17
Station X
Moderator
 
Station X's Avatar
 
Join Date: Jan 2003
Location: Ipswich, Suffolk, IP4, UK.
Posts: 15,426
Default Re: Valve testing a 4212

The OP was referring to the advice in post #3. ie measure the cathode to grid voltage.
__________________
Graham. Forum Moderator

Keep the soldering iron hot.
Station X is online now   Reply With Quote
Old 16th Jan 2020, 5:39 pm   #18
rambo1152
Octode
 
rambo1152's Avatar
 
Join Date: May 2010
Location: Manchester, UK.
Posts: 1,578
Default Re: Valve testing a 4212

Quote:
Originally Posted by Station X View Post
The OP was referring to the advice in post #3. ie measure the cathode to grid voltage.
That's interesting, I don't suppose you could detect the space charge with an AVO 8 though...
__________________
--
Graham.
G3ZVT
rambo1152 is offline   Reply With Quote
Reply

Thread Tools



All times are GMT +1. The time now is 10:38 am.


All information and advice on this forum is subject to the WARNING AND DISCLAIMER located at https://www.vintage-radio.net/rules.html.
Failure to heed this warning may result in death or serious injury to yourself and/or others.


Powered by vBulletin®
Copyright ©2000 - 2020, vBulletin Solutions, Inc.
Copyright ©2002 - 2020, Paul Stenning.