transmitter tube amp - 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 29th October 2006, 09:48 PM   #21
Tweeker is offline Tweeker  United States
diyAudio Member
 
Join Date: Dec 2004
Location: Cincinnati, Ohio
Western Electric 43A theatre amplifier schematic from Nutshell High Fidelity. Note the 211 triodes used as rectifier diodes and another pair as final stage.

Click the image to open in full size.

Click the image to open in full size.
__________________
Be sure your foil hat has a good low impedance ground.
  Reply With Quote
Old 29th October 2006, 10:02 PM   #22
Tweeker is offline Tweeker  United States
diyAudio Member
 
Join Date: Dec 2004
Location: Cincinnati, Ohio
Quote:
I have found this http://www.tube-fullmusic.com/produ...roduct0-805.htm It seems the curve of a pentode
do these tubes normally work in class A2 or AB2 (with grid current) ?
These are the grid current curves, not plate current is why they have thier shape. Yes, the 805 tube is normally used with grid current. Class B(2) amplifier/modulator or class C amplifier/oscillator use would be the norm in thier original typical usage.
__________________
Be sure your foil hat has a good low impedance ground.
  Reply With Quote
Old 30th October 2006, 02:58 AM   #23
diyAudio Member
 
Join Date: Oct 2006
I have both the types of tube solckets for the 212's, the horizontal chassis mount and the vertical front panel mount as shown in the rack panel above. I thought 813's were overkill enough, but I guess I'll try something with the 212's. My 212's were used originally in a theater amp. Thanks for all the info. The web is still amazing.

Sparky
  Reply With Quote
Old 30th October 2006, 07:46 AM   #24
7N7 is offline 7N7  United Kingdom
diyAudio Member
 
7N7's Avatar
 
Join Date: Jan 2003
Location: England
Tweeker:


Thanks so much; that sort of stuff is a real treat for me to see.

Anyone got a picture of John Logie Baird's TV set up? I read that because his system needed so much light, he had some enormous arc lamps driven by "a pair of enormous triodes running at 15,000V". I have no idea why one would drive arc lamps with triodes, but perhaps the light was more hi-fi?

As for the 955s, as there is some interest, I will look for the test results of my experiments.

I would not have thought of 955 as the right valve for phono. I think it's best to have some decent gm, hence the popularity of 417A/5842 etc. Choices would be EC8010, perhaps 6GK5 and one or two others like 437A or EC8020 for the rich. I did some work using the 416D planar triode (mu 250 gm 65), which would have worked probably but was tricky. I would quite like to have tried D3A triode strapped. Mu is 85, with gm up to 40 and Ca-g is only 2.7pf in triode mode.

Paul
__________________
Plug them in and light them up
  Reply With Quote
Old 30th October 2006, 08:02 AM   #25
7N7 is offline 7N7  United Kingdom
diyAudio Member
 
7N7's Avatar
 
Join Date: Jan 2003
Location: England
Default 849A

849A looks good for big SE fans, provided they fancy building a 2.5kV power supply.

82W at 3% distortion is very impressive.

Paul
__________________
Plug them in and light them up
  Reply With Quote
Old 30th October 2006, 11:46 AM   #26
diyAudio Member
 
Gold_xyz's Avatar
 
Join Date: Dec 2005
Location: Italy
Quote:
Originally posted by Tweeker
These are the grid current curves, not plate current is why they have thier shape. Yes, the 805 tube is normally used with grid current. Class B(2) amplifier/modulator or class C amplifier/oscillator use would be the norm in thier original typical usage.
hi Tweeker

This graph seems me different from the original datasheet...
http://frank.pocnet.net/sheets/111/8/805.pdf
Click the image to open in full size.
( from the http://www.tube-fullmusic.com/produc...oduct0-805.htm )
Y axis = Ia anode current ?
X axis = Ua anode voltage
Curves = Ug grid voltage

update..
perhaps is the axis x more expanded...

bye

  Reply With Quote
Old 30th October 2006, 11:18 PM   #27
diyAudio Member
 
Join Date: Jul 2003
Location: Ann Arbor, MI
Hey-Hey!!!,
My 813 project is comming along. B+ of ~650, U-L at 37.5% thanks to a custom pair of output TX's. They deserve a bit of space... I acquired a Peerless S-271-S, and had it unwound. It is a 2.25" stack of 1.75" EI rated for 80W. It has 8 layers of primary on each side of CT, so I get end-of-layer taps at any multiple of 12.5%, so I'm getting them wound with the first three layers tapped. Stacked with .009" M3.

The circuit is a pentode( or faux pentode cascode ) diff amp. CCS by MOSFET and a E-Linear connection to 25% taps( each half of the diff amp attached to the side of the OPTx that it is feeding the g1 to). Gapped C-core grid choke to side-step the 30k grid circuit limit.

B+ is done LC-LC with 10 Hy and parallel damper diodes and 660vac PIO caps. ~150 mA per 813 idle. With a 5k a-a load, and 37.5% U-L it will still be Class A, and as such ought to deliver me power on par with the output's rating. I can always have another coil wound for additional stacking of Iron if it turns out I need more core area.
cheers,
Douglas
__________________
the Tnuctipun will return
  Reply With Quote
Old 31st October 2006, 01:10 AM   #28
diyAudio Member
 
Join Date: Oct 2006
Bandersnatch, It sounds very interesing. I don't understand very much of what you posted, but can you post a schematic at least of the audio circuit, especially the UL taps and feedback arrangement. Thanks.

Sparky
  Reply With Quote
Old 31st October 2006, 10:32 AM   #29
diyAudio Member
 
Join Date: Jul 2003
Location: Ann Arbor, MI
Hey-Hey!!!,
I will direct you to an already published schematic.

http://www.audioroundtable.com/Group...cts/Merlin.pdf

That is the nuts an' bolts of it.
cheers,
Douglas
__________________
the Tnuctipun will return
  Reply With Quote
Old 31st October 2006, 02:53 PM   #30
diyAudio Member
 
Join Date: Oct 2006
Hey Bandersnatch,

Thanks for the schematic. How do you achieve CCS1 and CCS2 and are they really necessary? It seems like resistors would be o.k. here as well for the bias blocking inductor. I am trying to understand the precise advantages of Douglas Piccard's schematic.

Please post your results when the amp is done. It will be most intersting. I plan to do the same.

Sparky
  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
832A transmitter tube Mr. Triatic Tubes / Valves 0 3rd March 2002 08:47 PM


New To Site? Need Help?

All times are GMT. The time now is 07:15 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