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

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

Notices

Components and Circuits For discussions about component types, alternatives and availability, circuit configurations and modifications etc. Discussions here should be of a general nature and not about specific sets.

Closed Thread
 
Thread Tools
Old 21st May 2019, 7:10 pm   #1
geeoboeh2s
Rest in Peace
 
Join Date: Mar 2010
Location: Berkshire, UK.
Posts: 72
Default An interesting thermionic device.

There are only two contacts, a 1mm lead and a normal valve top cap.

There is no longer a vacuum in the glass envelop with the 1mm lead. The other envelop with the top cap has a much finer wire. The two devices meet in a metal housing. The housing is probably steel - it is magnetic.

Could it be a surge arrester or fuse with the housing acting as a heat sink

What is it likely to have been used for?

Chris
Attached Thumbnails
Click image for larger version

Name:	P5080005.jpg
Views:	267
Size:	39.4 KB
ID:	183561   Click image for larger version

Name:	P5080006.jpg
Views:	205
Size:	36.4 KB
ID:	183562  
geeoboeh2s is offline  
Old 21st May 2019, 7:31 pm   #2
ekjdm14
Banned
 
Join Date: Feb 2019
Location: Congleton, Cheshire, UK.
Posts: 609
Default Re: An interesting thermionic device.

I'm probably miles off here, but I thought it could be some kind of spark igniter with the 1mm lead being an electrode and the part below being some kind of current limiting/short circuit protection in case the electrode were to get too close to it's opposite number... As said, likely way off the mark but am also fascinated to learn what it actually is & it's intended use.
ekjdm14 is offline  
Old 21st May 2019, 7:35 pm   #3
G6Tanuki
Dekatron
 
G6Tanuki's Avatar
 
Join Date: Apr 2012
Location: Wiltshire, UK.
Posts: 13,953
Default Re: An interesting thermionic device.

I'm wondering about the magnetic metal bit - and pondering if it could be some sort of TR-switch for inserting in a waveguide?

(these were designed to ionise very quickly when subjected to a pulse of microwave energy, so providing a short-circuit - often in conjunction with a 1/4-wave of waveguide - across the receiver input to prevent the receiver being desensitized).


If it is a TR-switch imay not have contained a vacuum; TR-switches often used Helium or sometimes even water-vapour.
G6Tanuki is offline  
Old 21st May 2019, 9:10 pm   #4
G8HQP Dave
Rest in Peace
 
Join Date: Sep 2008
Location: Solihull, West Midlands, UK.
Posts: 4,872
Default Re: An interesting thermionic device.

The bit below the wire looks rather like it has a glass-encapsulated diode inside it. However, I realise that this type of package was used for other devices too.
G8HQP Dave is offline  
Old 22nd May 2019, 8:52 am   #5
M0FYA Andy
Nonode
 
Join Date: May 2007
Location: Preston, Lancashire, UK.
Posts: 2,510
Default Re: An interesting thermionic device.

I've searched the online valve museums, but failed to find anything looking like this.

Andy
M0FYA Andy is offline  
Old 22nd May 2019, 10:48 am   #6
Julesomega
Nonode
 
Julesomega's Avatar
 
Join Date: Dec 2012
Location: Stockport, Greater Manchester, UK.
Posts: 2,085
Default Re: An interesting thermionic device.

Maybe the steel housing provided a third internal connection?
__________________
- Julian

It's good here
Julesomega is offline  
Old 22nd May 2019, 11:37 am   #7
geeoboeh2s
Rest in Peace
 
Join Date: Mar 2010
Location: Berkshire, UK.
Posts: 72
Default Re: An interesting thermionic device.

I've added some more pictures taken from different angles.
It looks as though the 1mm wire terminates in a small block inside the envelope. Again this looks coppery but may be the same material as the housing.
I thought that the hole in the housing may contain an Allen screw but I have a reasonable selection and nothing fits.

Chris
Attached Thumbnails
Click image for larger version

Name:	DSC_3325.jpg
Views:	141
Size:	29.0 KB
ID:	183623   Click image for larger version

Name:	DSC_3326.jpg
Views:	132
Size:	26.2 KB
ID:	183624   Click image for larger version

Name:	DSC_3327.jpg
Views:	125
Size:	50.9 KB
ID:	183625  
geeoboeh2s is offline  
Old 22nd May 2019, 11:55 am   #8
GMB
Dekatron
 
GMB's Avatar
 
Join Date: Aug 2003
Location: near Reading (and sometimes Torquay)
Posts: 3,086
Default Re: An interesting thermionic device.

My guess is that it is an X-ray tube.

(There is a very wide range of shapes and styles of these)
GMB is offline  
Old 22nd May 2019, 1:07 pm   #9
kalee20
Dekatron
 
Join Date: Feb 2007
Location: Lynton, N. Devon, UK.
Posts: 7,061
Default Re: An interesting thermionic device.

I've seen nothing like this either! However, I doubt that it is thermionic. There aren't enough connections for a heater, and I can't see any any other way of heating a cathode to emitting temperature (eg lens and sun's rays).

There seems to be no getter.

Is there any continuity between the two connections? I'd guess not, but if there is, it could be a vacuum thermistor type of thing.
kalee20 is offline  
Old 22nd May 2019, 1:25 pm   #10
geeoboeh2s
Rest in Peace
 
Join Date: Mar 2010
Location: Berkshire, UK.
Posts: 72
Default Re: An interesting thermionic device.

If a source gets hot enough it will emit electrons but these will just form a space charge and there will not be a flow of current until a positively charged source is introduced. I perhaps should not have said thermionic without being able to confirm that the wire gets sufficiently hot. However both tubes are evacuated, or at least were.
The tube with the 1mm wire definitely had a getter. Apart from the deposit on the glass due to the loss of vacuum the structure can still be seen inside.

Chris
geeoboeh2s is offline  
Old 22nd May 2019, 1:36 pm   #11
ms660
Dekatron
 
ms660's Avatar
 
Join Date: Apr 2011
Location: Cornwall, UK.
Posts: 13,454
Default Re: An interesting thermionic device.

I wonder if it's magnetron related?

Lawrence.
ms660 is offline  
Old 22nd May 2019, 2:09 pm   #12
barrymagrec
Octode
 
Join Date: Dec 2017
Location: Morden, Surrey, UK.
Posts: 1,552
Default Re: An interesting thermionic device.

Some sort of possibly incomplete spark gap switch detonator for an atomic bomb?
barrymagrec is offline  
Old 22nd May 2019, 5:07 pm   #13
Martin G7MRV
Heptode
 
Join Date: May 2008
Location: Selby, North Yorkshire, UK.
Posts: 949
Default Re: An interesting thermionic device.

Atomic detonators used Krytron cold cathode switch tubes.

But I think the spark gap idea might be the right way to go, some form of triggered spark gap?


Take a look here http://www.ase-museoedelpro.org/Muse...adar_tubes.htm

maybe a klystron or magnetron but incomplete?
__________________
I got food in ma belly and a license for ma telly

My Blog - http://g7mrv.blogspot.com

Last edited by Martin G7MRV; 22nd May 2019 at 5:30 pm.
Martin G7MRV is offline  
Old 23rd May 2019, 1:12 pm   #14
Skywave
Rest in Peace
 
Join Date: Jun 2006
Location: Chard, South Somerset, UK.
Posts: 7,457
Default Re: An interesting thermionic device.

My guess is some sort of microwave T-R switch: it has that 'certain look'.

Al.
Skywave is offline  
Old 24th May 2019, 9:58 pm   #15
Malcolm G6ANZ
Octode
 
Malcolm G6ANZ's Avatar
 
Join Date: Feb 2006
Location: Bristol, UK.
Posts: 1,030
Default Re: An interesting thermionic device.

I've been having a search through Google for this device, as one does. The closest I can see is here:
http://www.electricstuff.co.uk/sparkgaps.html#krytron
Sylvania 1B26

Malcolm
Malcolm G6ANZ is offline  
Old 24th May 2019, 11:10 pm   #16
McMurdo
Dekatron
 
McMurdo's Avatar
 
Join Date: Jun 2009
Location: Staffordshire Moorlands, UK.
Posts: 5,263
Default Re: An interesting thermionic device.

A quick google shows some of those radar valves contain radioactive cesium or radium to assist the ionisation threshold.
__________________
Kevin
McMurdo is offline  
Closed Thread

Thread Tools



All times are GMT +1. The time now is 1:10 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 - 2024, vBulletin Solutions, Inc.
Copyright ©2002 - 2023, Paul Stenning.