No not Again...Aikido Plate dissipation question
 User Name Stay logged in? Password
 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
john65b
diyAudio Member

Join Date: Jan 2005
Location: Chicago
No not Again...Aikido Plate dissipation question

OK, this has been asked ad nauseum, but wanna make sure I don't fry a 6H30.

What I have on the 6H30 Output Tube:

V at Plate - Top Section - 204vdc
I of tube 24ma
V at Plate - Bottom Section - 102vdc

So 204 * .024, I get 4.89 watts and max plate dissipation is 4 watts (can be pushed to 6 says BAT)

Now since tubes are stacked, I am to use 1/2 B+ when figuring the plate dissipation, so top plate is 204vdc, bottom plate is 102vdc, 1/2 (204) * .024 and get 2.44 watts.

Now Andy Pairo asked this a while back and indicated the B+ should not be halved as the plate current is same in both sections of tube...

E88CC dissipation in Aikido

As far as I see it, this would be correct, as the top section dissipation (with total voltage across section - in other words, subtracting the cathode voltage from plate voltage) is (204-102)* .024 and bottom section dissipation is (102 - 0)* .024 = 4.89 watts total in my case.

And to make this thread even more annoying, look at the following from Tubecad, where current is 40ma with a top plate of 150vdc giving 6 watts dissipation on a 6H30 if we don't half the top plate voltage....

What gives?? Driving me nuts. Seems like quite a few voltage / current selections in the Aikido manual also push / exceed the tube dissipation limits (if top plate voltage is not halved)...

The input tube is a 6N1P at 204vdc and 5ma, not that this matters to my question...
Attached Images
__________________
I Speak Spanish to God, Italian to Women, French to Men, and German to My Horse. Charles V

Last edited by john65b; 8th June 2014 at 12:18 AM.

 8th June 2014, 12:35 AM #2 ballpencil   diyAudio Member   Join Date: Nov 2013 Replace those tubes with resistors of the same value. Then it's obvious that each resistor get half B+ and will dissipate half B+ multiplied by the idle current. Edit: then it's a matter of peeking at the spec sheet and check the max dissipation PER SECTION. Spec sheet usually states dissipation for each plate, not in total. This should make sense if the tube in question is dissimilar triodes or triode-pentode in one bottle. Last edited by ballpencil; 8th June 2014 at 12:45 AM.
 8th June 2014, 12:41 AM #3 john65b   diyAudio Member     Join Date: Jan 2005 Location: Chicago Yup. Good point...Why would Broskie publish instructions that exceed the tube ratings? __________________ I Speak Spanish to God, Italian to Women, French to Men, and German to My Horse. Charles V
 8th June 2014, 01:03 AM #4 ballpencil   diyAudio Member   Join Date: Nov 2013 Uhh.. no he didnt. I haven't check 6H30 spec sheet but if as you said they are 6 watts max dissipation per plate then each plate dissipates approx 75v x 40mA = 3 watts. You can still double the idle current to 80mA before you reach max plate dissipation.
 8th June 2014, 01:16 AM #5 john65b   diyAudio Member     Join Date: Jan 2005 Location: Chicago Max plate dissipation is 4 watts. Is that 4 watts each Triode? So 8 watts total? __________________ I Speak Spanish to God, Italian to Women, French to Men, and German to My Horse. Charles V Last edited by john65b; 8th June 2014 at 01:23 AM.
 8th June 2014, 01:23 AM #6 john65b   diyAudio Member     Join Date: Jan 2005 Location: Chicago Whoops, Sorry, looks like I should have done a little more homework.... 6H30 Center design points: 1.Heater voltage………………………………….6.0-6.6 V 2.Maximum plate voltage..………………………250V 3.Maximum plate voltage for closed tube……….1050V 4.Maximum grid voltage in pulse mode t<=100uS…-50V 5.Maximum heater-cathode voltage……………..400V 6.Maximum pulse current for each triode……….6A 7.Maximum cathode current for each triode…….100 mA 8.Maximum plate dissipation for each triode……4 Watts 9.Maximum grid dissipation for each triode…….0.4 Watts 10.Maximum grid resistance…………………….300 kOhm 11.Maximum bulb temperature………………….250 degrees C __________________ I Speak Spanish to God, Italian to Women, French to Men, and German to My Horse. Charles V
 8th June 2014, 01:36 AM #7 Johan Potgieter   diyAudio Member   Join Date: May 2005 Location: Pretoria, South Africa I did not look up the 6H30 specs, but usually the maximum allowed power for both triodes is not twice that of one section; some 50% more (heat inside glass etc.). This particularly for plate dissipations of several watt per triode. It varies somewhat from one double triode to the next.
 8th June 2014, 02:28 AM #8 ballpencil   diyAudio Member   Join Date: Nov 2013 That's funny. Most people i know say that those numbers on tube spec sheets are too conservative so running each triode at its max dissipation is totally safe. You do want to run them at somewhere 75% max dissipation for long life.

 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 Rules
 Forum Jump User Control Panel Private Messages Subscriptions Who's Online Search Forums Forums Home Site     Site Announcements     Forum Problems Amplifiers     Solid State     Pass Labs     Tubes / Valves     Chip Amps     Class D     Power Supplies     Headphone Systems Source & Line     Analogue Source     Analog Line Level     Digital Source     Digital Line Level     PC Based Loudspeakers     Multi-Way     Full Range     Subwoofers     Planars & Exotics Live Sound     PA Systems     Instruments and Amps Design & Build     Parts     Equipment & Tools     Construction Tips     Software Tools General Interest     Car Audio     diyAudio.com Articles     Music     Everything Else Member Areas     Introductions     The Lounge     Clubs & Events     In Memoriam The Moving Image Commercial Sector     Swap Meet     Group Buys     The diyAudio Store     Vendor Forums         Vendor's Bazaar         Sonic Craft         Apex Jr         Audio Sector         Acoustic Fun         Chipamp         DIY HiFi Supply         Elekit         Elektor         Mains Cables R Us         Parts Connexion         Planet 10 hifi         Quanghao Audio Design         Siliconray Online Electronics Store         Tubelab     Manufacturers         AKSA         Audio Poutine         Musicaltech         Holton Precision Audio         CSS         Dx Classic Amplifiers         exaDevices         Feastrex         GedLee         Head 'n' HiFi - Walter         Heatsink USA         miniDSP         SITO Audio         Twin Audio         Twisted Pear         Wild Burro Audio

 Similar Threads Thread Thread Starter Forum Replies Last Post pforeman Tubes / Valves 6 4th September 2011 08:19 PM Loren42 Tubes / Valves 7 28th April 2011 10:05 AM Rob11966 Tubes / Valves 12 7th August 2009 01:33 PM Captn Dave Tubes / Valves 4 20th April 2009 05:45 AM Andypairo Tubes / Valves 6 20th January 2007 06:29 PM

 New To Site? Need Help?

All times are GMT. The time now is 10:20 AM.