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 > Offered and Wanted Messages > Sets, Parts and Service Information Wanted (private buyers only, no swaps)

Notices

Sets, Parts and Service Information Wanted (private buyers only, no swaps) If you need help obtaining components, sets or equipment, post a message here. Private buyers only - no traders. No swaps.

Closed Thread
 
Thread Tools
Old 24th Apr 2018, 3:57 pm   #1
GrimJosef
Nonode
 
Join Date: Sep 2007
Location: Oxfordshire, UK.
Posts: 2,673
Default WTD: A couple of 'past it' EM34s

I'm curious about how these work so I'm looking for a couple of 'past it' ones to tinker with. I'm going to disassemble one of them, so that could be a completely dead one, both electrically and optically (although I can't use one that's been completely smashed flat !). I'd like the other one to be working electrically (decent emission from the cathode and not shorting out or arcing over inside) but just too dim to be of any use in a set.

I'll happily pay postage plus whatever seems reasonable for the valves.

Cheers,

GJ
__________________
http://www.ampregen.com
GrimJosef is online now  
Old 24th Apr 2018, 4:16 pm   #2
TowerRadio
Tetrode
 
Join Date: Mar 2008
Location: Bristol, UK.
Posts: 93
Default Re: WTD: A couple of 'past it' EM34s

You might also include old/US EM4's as well.If they are going to be dissected?
TowerRadio is offline  
Old 24th Apr 2018, 4:18 pm   #3
Boater Sam
Banned
 
Join Date: Dec 2013
Location: Middlewich, Cheshire, UK. & Winter in the Philippines.
Posts: 3,897
Default Re: WTD: A couple of 'past it' EM34s

I have a few 'eyes' that are beyond use, not all EM34 but they are all similar, 6G5 etc.
Postage would be 3 for 2 or 3 unfortunately.
Boater Sam is offline  
Old 24th Apr 2018, 4:47 pm   #4
GrimJosef
Nonode
 
Join Date: Sep 2007
Location: Oxfordshire, UK.
Posts: 2,673
Default Re: WTD: A couple of 'past it' EM34s

I wasn't aware of the EM4 but I see it's basically the same valve only on a side-contact base, so yes, that would do.

I'm curious about the double-shadow arrangement that the EM34 has Sam, which I was thinking of those, but other types might be interesting too. I'll send a PM. In ther meantime I'm still on the lookout for the EM34s.

Thanks both !

Cheers,

GJ
__________________
http://www.ampregen.com
GrimJosef is online now  
Old 27th Apr 2018, 7:17 pm   #5
GrimJosef
Nonode
 
Join Date: Sep 2007
Location: Oxfordshire, UK.
Posts: 2,673
Default Re: WTD: A couple of 'past it' EM34s

Just to say thanks to Sam who's sending me some magic eyes, including one dim EM34. I am still after another one though, so if anyone has a goner they can spare me then that would be great. Once again, happy to pay postage and a reasonable price for the valve.

Cheers,

GJ
__________________
http://www.ampregen.com
GrimJosef is online now  
Old 23rd Jun 2018, 9:57 pm   #6
Chris55000
Heptode
 
Join Date: Aug 2007
Location: Walsall Wood, Aldridge, Walsall, UK.
Posts: 774
Default Re: WTD: A couple of 'past it' EM34s

Hi!

As the mods have left this thread open I can comment!

The EM34 has two separate anode structures of slightly different sizes, the top of each being extended out vertically by a thin rod that forms the deflection electrode.

The assembly is made in such a way that one of the deflection rods is much nearer to the target–anode than the other, this construction gives the eye it's two different sensitivities – the section with the rod closest to the target–anode is the more sensitive one that closes at –5V.

Nearly all EM34s have two permanently–closed "dummy shadows", these are produced by the two additional support rods for the cathode light shield.

A zero–bias "space–charge" grid internally connected to cathode is also fitted to these indicators.

The Telefunken EM35 is electrically identical in characteristics to the 6U5G/Y63, but is built like the pre–war TV4/ME41 with four commoned deflector-rods to give a "Maltese–Cross"
Display.

For some reason, all the data on end–viewed octal M.E's never mentions the deflection electrode in base–diagrams, and it isn't always shown in circuits either, Wireless World articles on Magic–Eye GDO's omit the deflection electrode (s) from the eye symbols!

Chris Williams

PS!

Forgot to mention Y63s aren't always consistent as regards to the fitting of the display–section "space–charge" grid – I've seen examples both with and without it – incidentally the S.C. grid is never shown in any American eye symbols!
__________________
It's an enigma, that's what it is! This thing's not fixed because it doesn't want to be fixed!

Last edited by Chris55000; 23rd Jun 2018 at 10:11 pm.
Chris55000 is offline  
Closed Thread

Thread Tools



All times are GMT +1. The time now is 12:59 pm.


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 - 2019, vBulletin Solutions, Inc.
Copyright ©2002 - 2019, Paul Stenning.