Traced an old valve with no specs - thoughts please - diyAudio
Go Back   Home > Forums > Amplifiers > Tubes / Valves
Home Forums Rules Articles diyAudio Store Gallery Wiki 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
Thread Tools Search this Thread
Old 13th August 2011, 05:16 AM   #1
diyAudio Member
Join Date: Mar 2005
Location: Melbourne Again
Default Traced an old valve with no specs - thoughts please

Hi people,

I've got hold of a decent sized bunch of MHLD6, an old duo-diode/triode valve from the 30's. Specs are pretty hard to find for them so I thought why not trace them out myself, I've never done this before but it seems to have worked, see attached.

I'm trying to ascertain the utility of these things, as I can probably get a lot more. They are all ex-government stock, I suspect ex PMG or Victorian Railways.

mu is about 23
rp is about 7.3k
gm is about 3000 umhos

No idea of max plate dissipation but the structure is a bit under twice the size of a 6SN7.

The curves don't look bad to me, but I'm not an expert and I haven't run any loadlines as I don't have a printer at the moment.

What do other people reckon?

EDIT: I've only bothered about the triode section, obviously.
Attached Files
File Type: pdf MHLD6.pdf (95.5 KB, 79 views)
  Reply With Quote
Old 13th August 2011, 10:52 AM   #2
bigwill is offline bigwill  United Kingdom
diyAudio Member
Join Date: Dec 2004
Location: UK
Looks very 6SN7-ish!
  Reply With Quote
Old 13th August 2011, 03:12 PM   #3
diyAudio Member
Join Date: May 2005
Location: near Duesseldorf
MHLD6 @ The National Valve Museum

MHLD 6, Tube MHLD6; Röhre MHLD 6 (MHLD6)

VR101 @ The National Valve Museum

Regards Andreas
  Reply With Quote
Old 14th August 2011, 05:13 AM   #4
diyAudio Member
Join Date: Mar 2005
Location: Melbourne Again
Originally Posted by bigwill View Post
Looks very 6SN7-ish!
That was my thought also, I was hoping it wasn't just wishful thinking on my part. It was introduced at around the same time as the 6J5 so that makes some sense I suppose.

Cheers Andreas, those pages are where I got the pinout etc. It seems to be impossible to get any more info than that though. Hence tracing it out myself.
  Reply With Quote
Old 14th August 2011, 05:06 PM   #5
diyAudio Member
Join Date: Apr 2010
This valve seems to have dropped out of sight very early. Neither the 1949 nor 1966 versions of the Wireless World / Iliffe Radio Valve Data manuals list it and the Mullard manual (1955 ish) gives no suggested alternative which is most unusual. Still, your measurements and the similarity to a DL63 should enable you to get some use out of them.

  Reply With Quote


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
Convert a non-valve amp to a Valve (tube) Amp seanthomas46 Instruments and Amps 17 20th April 2015 04:11 AM
Thoughts on Oatley K282 Valve Preamp? Maxwell Smart Tubes / Valves 17 11th December 2011 09:44 AM
Thoughts......? Brian Steele Subwoofers 6 7th June 2011 04:42 PM
Swap Shanling CD-T80 valve CD player for Quad valve equiment johnm Swap Meet 2 24th September 2009 12:15 PM
Your thoughts please Ken L Tubes / Valves 41 31st October 2002 08:44 PM

New To Site? Need Help?

All times are GMT. The time now is 09:19 AM.

vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2017 DragonByte Technologies Ltd.
Copyright ©1999-2017 diyAudio

Content Relevant URLs by vBSEO 3.3.2