Please educate me: Tube testing, the life test, and Grid Leakage - Page 3 - diyAudio
Go Back   Home > Forums > Amplifiers > Tubes / Valves

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 15th October 2012, 10:04 PM   #21
diyAudio Member
 
Join Date: Dec 2008
Quote:
Originally Posted by DF96 View Post
gm and plate resistance are related: Rp = mu / gm

Measure any two of these and you can calculate the third. You could measure Rp by varying Rs in your circuit and seeing how gain varies.
Then, knowing Rp, you can calculate gm from your results.

Seeing this response was a good moment. I think it puts many things together.

for a tube - the small signal parameters are as follows

........................ mu = gm x rp

where, mu is the maximum theoretical gain for a particular tube.
and rp is the plate resistance

for the common cathode amp above, Rp is connected in the circuit, so substitute Av for mu - without a load, the gain is as follows.

........................ Av = gm x rp//Rp

However, a switch could be connected in series with a load resistor - Rs.
Measurements, could be taken - switching the load resistor in and out.

so with a load resistor

....................... Av = gm x rp//Rp//Rs
.

Last edited by Uunderhill; 15th October 2012 at 10:17 PM.
  Reply With Quote
Old 16th October 2012, 10:20 AM   #22
DF96 is online now DF96  England
diyAudio Member
 
Join Date: May 2007
Yes.
  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
Testing with test-records of RIAA amp. Helmuth Analogue Source 5 14th July 2011 08:52 PM
Mullard 12AU7 tests bad when running grid leakage test? sbelyo Tubes / Valves 6 10th April 2011 09:13 PM
SMPS gate drive - please educate me Th3 uN1Qu3 Power Supplies 5 16th July 2010 04:48 PM
Amplifiers, AB comparative testing, a blind test method. destroyer X Solid State 34 29th September 2009 12:39 PM
Testing for cap leakage taj Parts 15 7th October 2007 08:31 AM


New To Site? Need Help?

All times are GMT. The time now is 11:01 AM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright 1999-2014 diyAudio

Content Relevant URLs by vBSEO 3.3.2