Radio Valve advice please - UK Vintage Radio Repair and Restoration Discussion Forum

Dr-Watts · 6th Feb 2011, 10:28 pm

Hi all.
I've recently aquired an AVO Mk3 Valve tester and there's a box of NOS & used valves with it.
I've come accross some interesting ones that I'd like to identify and find out what part of the circuit they belong to.
I'm thinking about building a 1 valve radio and would love to find a circuit that could possible suit any of these.
6SG7 X7
6J5GT X1
D62 X1
mullard PM1HL X1

These are all NOS in their original boxes. Quite a nice addition

Anyway, over to the pro's.

Kind Regards
Dave W

Alan Stepney · 6th Feb 2011, 10:42 pm

6J5 is a triode, effectively one half of a 6SN7. A useful valve for audio and low-ish RF.
Some early signal generators used them up to around 30mc/s, although they are best known for audio use.

6SG7 is a vari-mu RF pentode.

Herald1360 · 7th Feb 2011, 12:45 am

With 7 6SG7 you could use 5 of them to build a superhet with only 1 valve (type) in it. PW did an article on using the 6K7 that way sometime late 50s ish.

paulsherwin · 7th Feb 2011, 1:01 am

There aren't too many 6SG7s around on this side of the pond. Looking at a data sheet it looks as if it may have been an early US radar valve. You can probably use it in any one valve circuit specifying a 6K7 or EF39 though the characteristics are different.

You could use a 6J5 to add an audio amp stage to your one valver making it a two valver. This might produce enough output to drive a speaker with an output transformer.

kalee20 · 7th Feb 2011, 1:58 pm

Quote:

Originally Posted by paulsherwin

You could use a 6J5 to add an audio amp stage ... might produce enough output to drive a speaker with an output transformer.

It will. In fact you can even plug a 6J5 in place of a 6V6 (the pin connections just happen to match, with the 6J5 of course having no screen-grid connection), and get decent sound. Of course, the circuit won't be optimised, but it does work.

6th Feb 2011, 10:28 pm	#1
Dr-Watts Heptode Join Date: Dec 2006 Location: Milton Keynes, Buckinghamshire, UK. Posts: 696	Radio Valve advice please Hi all. I've recently aquired an AVO Mk3 Valve tester and there's a box of NOS & used valves with it. I've come accross some interesting ones that I'd like to identify and find out what part of the circuit they belong to. I'm thinking about building a 1 valve radio and would love to find a circuit that could possible suit any of these. 6SG7 X7 6J5GT X1 D62 X1 mullard PM1HL X1 These are all NOS in their original boxes. Quite a nice addition Anyway, over to the pro's. Kind Regards Dave W __________________ Do you have the scope to be a TV repair man Last edited by Dr-Watts; 6th Feb 2011 at 10:36 pm.

6th Feb 2011, 10:42 pm	#2
Alan Stepney Rest in Peace Join Date: Feb 2008 Location: Dorset, UK. Posts: 947	Re: Radio Valve advice please 6J5 is a triode, effectively one half of a 6SN7. A useful valve for audio and low-ish RF. Some early signal generators used them up to around 30mc/s, although they are best known for audio use. 6SG7 is a vari-mu RF pentode.

7th Feb 2011, 12:45 am	#3
Herald1360 Dekatron Join Date: Feb 2007 Location: Leominster, Herefordshire, UK. Posts: 16,536	Re: Radio Valve advice please With 7 6SG7 you could use 5 of them to build a superhet with only 1 valve (type) in it. PW did an article on using the 6K7 that way sometime late 50s ish. __________________ ....__________ ....\|____\|\|__\|__\_____ .=.\| _---\__\|__\|_---_\|. .........O..Chris....O

7th Feb 2011, 1:01 am	#4
paulsherwin Moderator Join Date: Jun 2003 Location: Oxford, UK Posts: 27,963	Re: Radio Valve advice please There aren't too many 6SG7s around on this side of the pond. Looking at a data sheet it looks as if it may have been an early US radar valve. You can probably use it in any one valve circuit specifying a 6K7 or EF39 though the characteristics are different. You could use a 6J5 to add an audio amp stage to your one valver making it a two valver. This might produce enough output to drive a speaker with an output transformer.