|
Home | Forums | Rules | Articles | diyAudio Store | Blogs | Gallery | Wiki | Register | Donations | FAQ | Calendar | Search | Today's Posts | Mark Forums Read | Search |
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 |
![]() |
|
Thread Tools | Search this Thread |
![]() |
#1 |
diyAudio Member
Join Date: Jul 2008
|
![]()
Hi, I posted this question once before and got a few links to data sheets which did not answer the question. I need to know what the transconductance spec is for a KT-90 in GM. Thanks
|
![]() |
![]() |
#2 |
Banned
Join Date: Jun 2011
|
Zen Mod posted it for you in PDF.
13.4@250v 10.1@400v pentode 12.7@250 triode |
![]() |
![]() |
#3 |
Banned
Join Date: Jun 2011
|
gm = I out / V in
|
![]() |
![]() |
#4 | |
diyAudio Moderator
|
Quote:
In which case around: 14000umhos in pentode at 250Vp, 250Vs; 8800umhos in pentode at 400Vp, 300Vs; 15000umhos in triode connection at 250Vp From this data sheet: http://www.mif.pg.gda.pl/homepages/f...084/k/KT90.pdf GM is not a unit of measure and can be specified in lots of units like mA/V, uS, and umhos (obsolete actually)
__________________
"To argue with a person who has renounced the use of reason is like administering medicine to the dead." - Thomas Paine |
|
![]() |
![]() |
#5 |
diyAudio Member
Join Date: May 2007
|
And its not GM. Should be small g (conductance) and subscript m (mutual). G is Giga (10^9) and I don't know what M is.
|
![]() |
![]() |
#6 |
diyAudio Member
Join Date: Jan 2002
Location: nowhere
|
M can be Mama, in which case GM is GigaMama and a synonym for mother in law. Or M can be Mega, so we have GigaMega which is synonomous with the common 1000000000000000 integer.
|
![]() |
![]() |
#7 |
diyAudio Member
Join Date: Jul 2007
Location: Metro Atlanta, Georgia
|
speakerfritz:
GloBug has the right idea but that's not quite correct. g_m is the slope of the I/V curve at a particular DC operating point. Take, for example, the plot on page 5 of the link in kevinkr's comment. Pick one of the curves, and pick a point on that curve. The slope of the line tangent to that point is the g_m at that operating point. See attached. |
![]() |
![]() |
#8 |
diyAudio Member
Join Date: Dec 2001
Location: Hickory, NC
|
Don't forget that gm varies with cathode current too, roughly as the square root. So there is no "the gm" for any tube. Its a variable you have to measure off the curves (see above) or locally interpolate with the square root rule.
|
![]() |
![]() |
#9 | |
diyAudio Moderator
|
Quote:
@ speakerfritz, posts #7, and 8 are particularly relevant. Post #6 is just funny. . ![]()
__________________
"To argue with a person who has renounced the use of reason is like administering medicine to the dead." - Thomas Paine |
|
![]() |
![]() |
#10 |
Anatoliy Lisovskiy
diyAudio Member
|
GM is General Motors. One of Generals that won Cold War (i.e. benefited from it)
![]() umho is micro mho, mmho is mili mho, mho is backward written Ohm because Ohm is volt/ampere, mho is ampere/volt. I think initially it was a joke.
__________________
!!!Warning!!! Single Ended Class-A-Holism is addictive!!! |
![]() |
![]() |
Thread Tools | Search this Thread |
|
|
![]() |
||||
Thread | Thread Starter | Forum | Replies | Last Post |
How to align tape and set bias for Revox G36 in plain English, please! | Salli | Analogue Source | 8 | 20th April 2011 09:24 PM |
90+90 volt rails | east electronics | Solid State | 42 | 5th April 2011 02:38 PM |
EI KT-90 news | linko | Tubes / Valves | 5 | 10th February 2007 07:50 AM |
Need PP KT-88 amp design and KT-88 for triode use? | Norris Wilson | Tubes / Valves | 7 | 23rd February 2005 01:12 PM |
Need Amp For 90-0-90 V DC | Drafance007 | Solid State | 15 | 12th October 2003 09:03 PM |
New To Site? | Need Help? |