Videokarma.org

Go Back   Videokarma.org TV - Video - Vintage Television & Radio Forums > Vintage TV & Radio Tech Forum

We appreciate your help

in keeping this site going.
Reply
 
Thread Tools Display Modes
  #1  
Old 07-03-2014, 08:56 PM
bandersen's Avatar
bandersen bandersen is offline
RCA 741PCS
 
Join Date: Mar 2009
Location: Chicago, IL
Posts: 8,085
Metal CRT vacuum pinch off seal ?

I just received a 12LP4 with a damaged base and was surprised to find this inside.

It looks like the base is pressed glass and has a pinch off vacuum seal made from two types of metal.



Pretty sure every other one I've ever seen is a glass nipple like this mangled 12QP4


It still has some life left


__________________
Here are my Vintage Radio & TV YouTube Channel and Photo Gallery

Last edited by bandersen; 07-03-2014 at 09:06 PM.
Reply With Quote
  #2  
Old 07-03-2014, 09:16 PM
NoPegs's Avatar
NoPegs NoPegs is offline
The glass is -3dB.
 
Join Date: Mar 2014
Location: Amish Country PA.
Posts: 376
Does it have continuity to any of the normal connections, by chance?

I can't tell from the full rez photos, but it looks like an extremely well done rebuild, or I'm just seeing a step line in the neck where they shifted glass types to match the stem to the bulb. Confirm/Deny that it is a rebuild?


I seem to have memory of seeing this "HVAC" style seal on some mid 90s vintage Toshiba projection set tubes when I went to air them up before disposal. (This was 2005, they had terrible burn-in among other things, so no great loss to society in my opinion... The only unit I actually regret being party to disposal of was the Dimensia.)
Reply With Quote
  #3  
Old 07-03-2014, 09:20 PM
bandersen's Avatar
bandersen bandersen is offline
RCA 741PCS
 
Join Date: Mar 2009
Location: Chicago, IL
Posts: 8,085
I haven't checked for continuity to any pins. I'm pretty sure it's not a rebuild. It has an RCA base and neck markings and the Admiral stamped on the bell indicates it's the original that came with the 1949 TV.
__________________
Here are my Vintage Radio & TV YouTube Channel and Photo Gallery
Reply With Quote
  #4  
Old 07-03-2014, 09:52 PM
jr_tech's Avatar
jr_tech jr_tech is offline
VideoKarma Member
 
Join Date: Sep 2009
Posts: 4,510
I don't have any hard data, but some considered the copper pinch off to be better (but more expensive) than the glass tip seal, since hot glass can outgass during the sealing process.
The 15GP22 has a copper pinch.

jr
Reply With Quote
  #5  
Old 07-03-2014, 10:11 PM
Eric H's Avatar
Eric H Eric H is offline
Administrator
 
Join Date: Jun 2002
Location: So. Calif
Posts: 11,565
I've seen this in some early (like 46-48) 10BP4's.
Reply With Quote
Audiokarma
  #6  
Old 07-03-2014, 11:16 PM
mstaton's Avatar
mstaton mstaton is offline
"Book em Dano!"
 
Join Date: May 2011
Location: Caldwell, Id
Posts: 1,600
Some color roundie CRT's have those also

https://www.youtube.com/watch?v=aU-Jhmdl-MU
__________________
"It's a mad mad mad mad world" !!
http://www.youtube.com/user/mwstaton64?feature=mhee

Last edited by mstaton; 07-03-2014 at 11:40 PM.
Reply With Quote
  #7  
Old 07-04-2014, 10:02 AM
dieseljeep dieseljeep is offline
VideoKarma Member
 
Join Date: Jul 2010
Posts: 7,562
Quote:
Originally Posted by bandersen View Post
I haven't checked for continuity to any pins. I'm pretty sure it's not a rebuild. It has an RCA base and neck markings and the Admiral stamped on the bell indicates it's the original that came with the 1949 TV.
According to tube lore, RCA came out with the 12LP4, sometime in 1948.
That must be one of the earlier model 12" Admiral's.
Is that one of the two chassis models?
BTW, is that the original reading or did you rejuvenate it?
Reply With Quote
  #8  
Old 07-04-2014, 12:40 PM
bandersen's Avatar
bandersen bandersen is offline
RCA 741PCS
 
Join Date: Mar 2009
Location: Chicago, IL
Posts: 8,085
It's a single chassis. I just bought the bare 20Y1 chassis and CRT.
Admiral only used that chassis in four models 20X136, 145, 146 and 147. All came out in 1949. I'll be putting it into a 20X136.

No, I did not rejuvinate it.
__________________
Here are my Vintage Radio & TV YouTube Channel and Photo Gallery
Reply With Quote
Reply


Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump


All times are GMT -5. The time now is 04:00 PM.



Powered by vBulletin® Version 3.8.4
Copyright ©2000 - 2024, Jelsoft Enterprises Ltd.
©Copyright 2012 VideoKarma.org, All rights reserved.