Call Search
     

New to Ham Radio?
My Profile

Community
Articles
Forums
News
Reviews
Friends Remembered
Strays
Survey Question

Operating
Contesting
DX Cluster Spots
Propagation

Resources
Calendar
Classifieds
Ham Exams
Ham Links
List Archives
News Articles
Product Reviews
QSL Managers

Site Info
eHam Help (FAQ)
Support the site
The eHam Team
Advertising Info
Vision Statement
About eHam.net

   Home   Help Search  
Pages: [1]   Go Down
  Print  
Author Topic: brand new old stock 811a tube base loose,any good still??  (Read 2454 times)
VE7REN
Member

Posts: 473




Ignore
« on: January 16, 2012, 04:54:44 PM »

i found a box of used 811s, all the other 4 are good,and then there is one in a beautiful box,unopened it seems. the tube looks very nice. ,but, i take it out of the box,and check it out.

the base is loose from the glass on the tube. it has slight movement. everything looks fine otherwise... is it a junker? or hassomeone ever used a tube like this?

its a shame,but........any suggestions??
Logged
KF7CG
Member

Posts: 840




Ignore
« Reply #1 on: January 17, 2012, 10:57:45 AM »

Use a high temperature non-conductive cement and stabilize the base. If the tube seals haven't been damaged by stress on the leads, the tube should be fine. I have use this method with the old Octal based sweep tubes and HV rectifiers back when I was a young Ham with no money.

KF7CG
Logged
AD4U
Member

Posts: 2173




Ignore
« Reply #2 on: January 17, 2012, 01:07:03 PM »

I repaired some NOS RCA 811 tubes with loose bases by using JB Weld.  So far (over a year) of occassional use in my 30L1 there have been no problems from the heat.

Dick  AD4U
« Last Edit: January 17, 2012, 04:28:31 PM by AD4U » Logged
G3RZP
Member

Posts: 4731




Ignore
« Reply #3 on: January 17, 2012, 01:31:25 PM »

Another one is heat shrink tubing of the right diameter to just fit. Over the top of JBWeld, it should be good for as long as the tubes are.
Logged
W8JX
Member

Posts: 6092




Ignore
« Reply #4 on: January 17, 2012, 02:05:25 PM »

I like JB weld idea better as heat shrink degrades in high heat over time. I would not remove them by envelope after gluing them. I would pry them out of socket by base. 
Logged

--------------------------------------
All posted wireless using Win 8.1 RT, a Android tablet using 4G/LTE/WiFi or Sprint Note 3.
VE7REN
Member

Posts: 473




Ignore
« Reply #5 on: January 17, 2012, 04:14:11 PM »

ok. i will try the jb weld.

i am a little worried about plugging it in,powering up the amp and blowing something.but. i feel if it light up,and i idle it for a couple hrs,it should be fine for tx.....right.
Logged
VE7REN
Member

Posts: 473




Ignore
« Reply #6 on: January 17, 2012, 04:28:36 PM »

dick

before you put the jb weld,how loose was the base?and how easy was the jb weld to get in the gap??any suggestions?my base probably could turn if i forced it,but i will not do that. it would twist the terminals off inside
Logged
AD4U
Member

Posts: 2173




Ignore
« Reply #7 on: January 18, 2012, 05:36:13 AM »

The original cement on the 811 bases had come loose (I guess) due to time and handling.  The bases were loose but not hanging by the connecting wires.  They could be wiggled.

Putting a bead of JB Weld around the base at the glass to base junction solved the (my ) problem. 

I also repaired a very expensive 8950 tube in a Swan 700CX with JB Weld.  The top cap had come loose.  I put a small bead of JB Weld around the junction of the metal tube cap and the glass tube envelop.  Even with all the heat, that tube has been running fine for over 2 years.

In both cases I had nothing to lose by trying.

Dick  AD4U
Logged
VE7REN
Member

Posts: 473




Ignore
« Reply #8 on: January 18, 2012, 05:57:56 AM »

ok..thanks for the info fellas.i shall try it.
Logged
K8AXW
Member

Posts: 3905




Ignore
« Reply #9 on: January 18, 2012, 01:07:08 PM »

JB Weld makes several products.  Which one did you guys use for the tubes?  Can't find any temperature specs on their website.
Logged
W8JX
Member

Posts: 6092




Ignore
« Reply #10 on: January 18, 2012, 02:27:50 PM »

Use their standard one not the quick dry one as it has only about 1/2 the yield/shear strength of the one that takes a day to cure.
Logged

--------------------------------------
All posted wireless using Win 8.1 RT, a Android tablet using 4G/LTE/WiFi or Sprint Note 3.
AD4U
Member

Posts: 2173




Ignore
« Reply #11 on: January 18, 2012, 02:51:58 PM »

I used plain old gray (black and white two part) JB Weld.  Not the fast drying stuff.  In both applications and over the course of 2 years, the JB Weld has held up to the heat and the tubes are still going strong.

Dick  AD4U
Logged
K8AXW
Member

Posts: 3905




Ignore
« Reply #12 on: January 18, 2012, 08:48:37 PM »

Viel Danke!! Never know when that info will come in handy!
Logged
Pages: [1]   Go Up
  Print  
 
Jump to:  

Powered by MySQL Powered by PHP Powered by SMF 1.1.11 | SMF © 2006-2009, Simple Machines LLC Valid XHTML 1.0! Valid CSS!