Emission values? - diyAudio
Go Back   Home > Forums > Amplifiers > Tubes / Valves
Home Forums Rules Articles diyAudio Store Gallery Blogs Register Donations FAQ Calendar Search Today's Posts Mark Forums Read

Tubes / Valves All about our sweet vacuum tubes :) Threads about Musical Instrument Amps of all kinds should be in the Instruments & Amps forum

Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Reply
 
Thread Tools Search this Thread
Old 27th November 2015, 01:27 PM   #1
diyAudio Member
 
radiosmuck's Avatar
 
Join Date: Jul 2012
Location: Montreal
Default Emission values?

A while back I purchased a Sencore IV tube tester with the plan to check some output tubes I have laying around.
The Emission scale is calibrated from 0-120 and I would be interested to know what these figures represent?
Thanks
  Reply With Quote
Old 27th November 2015, 02:21 PM   #2
DF96 is offline DF96  England
diyAudio Member
 
Join Date: May 2007
0-120%, where 100% is what the datasheet says?
  Reply With Quote
Old 27th November 2015, 04:23 PM   #3
ragwire is offline ragwire  United States
diyAudio Member
 
ragwire's Avatar
 
Join Date: Nov 2015
Location: Des Moines, Iowa
Unfortunately there is no correlation between what an emissions type tester shows and actual current flow performance to the tube's datasheet. It was up to the discretion of the tube checker's engineers. Even high end transconductance testers vary by quite a percentage.
You would have to establish a baseline of your own to a good new tube of the same type.

cheers
Rob
  Reply With Quote
Old 27th November 2015, 05:43 PM   #4
20to20 is offline 20to20  United States
diyAudio Member
 
20to20's Avatar
 
Join Date: Jun 2010
Location: W-S, NC
Quote:
Originally Posted by radiosmuck View Post
A while back I purchased a Sencore IV tube tester with the plan to check some output tubes I have laying around.
The Emission scale is calibrated from 0-120 and I would be interested to know what these figures represent?
Thanks
It's a realative scale but gives general condition. If you look at the setup book you'll see that many tubes use the same control setup. But many of those tubes have slightly different performance characteristics and will give different meter output levels even if all are NOS, new or perfect... So you have to get to know how a good tube of any certain type tends to perform on the scale. Rectifiers, 5U4, 5T4, 5R4 all use the same settings but have different performance and will read differently on the meter. The book gives no "specs" to compare to.
  Reply With Quote
Old 27th November 2015, 10:01 PM   #5
kevinkr is offline kevinkr  United States
diyAudio Moderator
 
kevinkr's Avatar
 
Join Date: Sep 2004
Location: Boston, Massachusetts
Blog Entries: 6
Emission testers can provide only a very general guide to tube condition, and may indicate a tube is still good when it will not perform its intended function in a properly designed circuit, and conversely the reverse as well.

A much better figure of merit is the tube's transconductance which can be measured and compared to a range of values determined by the tester manufacturer to confirm whether a tube is good or bad.

In some instances testing the tube in an actual application circuit is the only way to know if a tube is good or not.

Leakage tests and tests for shorts are useful extras that hopefully this tester supports.
__________________
"Extraordinary claims require extraordinary evidence." - Carl Sagan
  Reply With Quote
Old 28th November 2015, 02:17 AM   #6
ragwire is offline ragwire  United States
diyAudio Member
 
ragwire's Avatar
 
Join Date: Nov 2015
Location: Des Moines, Iowa
Exactly what kevinkr said.
  Reply With Quote

Reply


Hide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

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
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
6L6G emission too high pilovis Tubes / Valves 12 11th December 2012 05:41 PM
Intermodulation Distortion Values below THD Values by SS Amps - is this possible ?? tiefbassuebertr Solid State 28 30th May 2011 12:20 PM
Emission - Double Triode Bone Tubes / Valves 4 5th July 2010 12:45 PM
Calibrating an emission tester kenpeter Tubes / Valves 5 30th June 2008 05:56 PM


New To Site? Need Help?

All times are GMT. The time now is 03:29 AM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2016 DragonByte Technologies Ltd.
Copyright 1999-2016 diyAudio

Content Relevant URLs by vBSEO 3.3.2