EF83 vs EF86. - UK Vintage Radio Repair and Restoration Discussion Forum

Tractorfan · 18th Feb 2015, 9:18 pm

Hi,
I have my Grundig TK149 in bits on the bench trying to sort a recording fault. The machine contains an EF86 followed by an EF83 (and then an ECL86 & an ECC81).
According to the National Valve Museum the pin outs between the '83 and the '86 are quite different, but other online sources give them as pin compatible. Squinting into the bottle, they do look remarkably similar. If so, could an EF86 be used in place of an 83, if only for testing purposes?
Also, why would a tape recorder have one of each instead of two EF86s?
Thanks.
Cheers, Pete.

G8HQP Dave · 18th Feb 2015, 9:28 pm

The EF83 is a variable gain pentode.

RF Burn · 18th Feb 2015, 9:56 pm

As Dave says, the EF83 is a the variable-mu (or remote cut-off) version of the EF86 and is used to enable compression or constant output level function in audio circuits. A useable feature in tape recorders so as the tape is not driven into saturation. Compare with the use of variable-mu pentodes in the I.F. stages of a superhet to obtain constant volume output from the radio coupled with the application of AGC to these stages.

Adrian

bobbyball · 18th Feb 2015, 10:50 pm

The EF83 is used in the "automatic record level" function. Not a very common valve. I rather supect an EF86 in the EF83 position would cause the record level circuit to function incorrectly.

Sideband · 19th Feb 2015, 9:50 pm

I have a feeling I have an EF83 in my valve stash. I was keeping it for a rainy day just in case. I'm never likely to use it so.....

Let me know if you want it.....mind you I have to find it first!

Tractorfan · 19th Feb 2015, 11:48 pm

Hi,
I think I got the two valves the wrong way round in their holders as the tape recorder which just about played back OK didn't any more. When I corrected them, it started working again. If the pin-outs are the same, (even though the characteristics are different), I would have expected something from the speaker

Thanks for the offer of your EF83 Sideband. If I get stuck, I'll pm you.
Cheers, Pete.

Sideband · 20th Feb 2015, 10:50 pm

I'll be up in the W/S over the weekend sometime. I'll let you know if I find the EF83. I doubt I'll ever use it so it's yours for cost of postage.

Pretty sure the pinouts are the same as EF86.

jjl · 21st Feb 2015, 10:55 am

Quote:

Originally Posted by Tractorfan

I think I got the two valves the wrong way round in their holders as the tape recorder which just about played back OK didn't any more. When I corrected them, it started working again. If the pin-outs are the same, (even though the characteristics are different), I would have expected something from the speaker

Pete

The pinout is different, EF83 here

http://www.r-type.org/exhib/aaa0527.htm

and EF86 here

http://www.r-type.org/exhib/aai0113.htm

the main difference is that g1 is on pin 2 for the EF83 and pin 9 for the EF86, so it's not too surprising that you had no sound when the 2 valves were swapped.

John

FERNSEH · 21st Feb 2015, 1:33 pm

There was even a 0.3amp heater version for TV sets. The PF83.

http://www.radiomuseum.org/tubes/tube_pf83.html

The vari-mu EF89 was used as the audio amplier in some record player amplifiers.

DFWB.

barretter · 21st Feb 2015, 1:59 pm

Quote:

Originally Posted by jjl

The pinout is different, EF83 here

http://www.r-type.org/exhib/aaa0527.htm

and EF86 here

http://www.r-type.org/exhib/aai0113.htm

the main difference is that g1 is on pin 2 for the EF83 and pin 9 for the EF86, so it's not too surprising that you had no sound when the 2 valves were swapped.

There seems to be some confusion on that website as the Philips PDF contradicts the information above it. My Mullard technical handbook gives exactly the same pin-out for both the EF83 and EF86 and I see that the PF83 also has the same pin-out as the EF86. Also the Philips handbook says that the EF86 and 83 have the same pin-out.

18th Feb 2015, 9:18 pm	#1
Tractorfan Dekatron Join Date: Mar 2008 Location: St. Frajou, l'Isle en Dodon, Haute Garonne, France.(Previously: Ellesmere Port, Cheshire, UK.) Posts: 3,183	EF83 vs EF86. Hi, I have my Grundig TK149 in bits on the bench trying to sort a recording fault. The machine contains an EF86 followed by an EF83 (and then an ECL86 & an ECC81). According to the National Valve Museum the pin outs between the '83 and the '86 are quite different, but other online sources give them as pin compatible. Squinting into the bottle, they do look remarkably similar. If so, could an EF86 be used in place of an 83, if only for testing purposes? Also, why would a tape recorder have one of each instead of two EF86s? Thanks. Cheers, Pete. __________________ "Hello?, Yes, I'm on the train, I might lose the signal soon as we're just going into a tunn..."

18th Feb 2015, 9:28 pm	#2
G8HQP Dave Rest in Peace Join Date: Sep 2008 Location: Solihull, West Midlands, UK. Posts: 4,872	Re: EF83 vs EF86. The EF83 is a variable gain pentode.

18th Feb 2015, 9:56 pm	#3
RF Burn Hexode Join Date: Apr 2008 Location: Ramsgate, Kent, UK. Posts: 252	Re: EF83 vs EF86. As Dave says, the EF83 is a the variable-mu (or remote cut-off) version of the EF86 and is used to enable compression or constant output level function in audio circuits. A useable feature in tape recorders so as the tape is not driven into saturation. Compare with the use of variable-mu pentodes in the I.F. stages of a superhet to obtain constant volume output from the radio coupled with the application of AGC to these stages. Adrian

18th Feb 2015, 10:50 pm	#4
bobbyball Octode Join Date: Jul 2011 Location: Stockport, Greater Manchester Posts: 1,214	Re: EF83 vs EF86. The EF83 is used in the "automatic record level" function. Not a very common valve. I rather supect an EF86 in the EF83 position would cause the record level circuit to function incorrectly. __________________ Robert

19th Feb 2015, 9:50 pm	#5
Sideband Dekatron Join Date: Oct 2003 Location: Croydon, Surrey, UK. Posts: 7,572	Re: EF83 vs EF86. I have a feeling I have an EF83 in my valve stash. I was keeping it for a rainy day just in case. I'm never likely to use it so..... Let me know if you want it.....mind you I have to find it first! __________________ There are lots of brilliant keyboard players and then there is Rick Wakeman.....

19th Feb 2015, 11:48 pm	#6
Tractorfan Dekatron Join Date: Mar 2008 Location: St. Frajou, l'Isle en Dodon, Haute Garonne, France.(Previously: Ellesmere Port, Cheshire, UK.) Posts: 3,183	Re: EF83 vs EF86. Hi, I think I got the two valves the wrong way round in their holders as the tape recorder which just about played back OK didn't any more. When I corrected them, it started working again. If the pin-outs are the same, (even though the characteristics are different), I would have expected something from the speaker Thanks for the offer of your EF83 Sideband. If I get stuck, I'll pm you. Cheers, Pete. __________________ "Hello?, Yes, I'm on the train, I might lose the signal soon as we're just going into a tunn..."

20th Feb 2015, 10:50 pm	#7
Sideband Dekatron Join Date: Oct 2003 Location: Croydon, Surrey, UK. Posts: 7,572	Re: EF83 vs EF86. I'll be up in the W/S over the weekend sometime. I'll let you know if I find the EF83. I doubt I'll ever use it so it's yours for cost of postage. Pretty sure the pinouts are the same as EF86. __________________ There are lots of brilliant keyboard players and then there is Rick Wakeman.....

21st Feb 2015, 1:33 pm	#9
FERNSEH Dekatron Join Date: Mar 2005 Location: Gateshead, Tyne and Wear, UK. Posts: 7,444	Re: EF83 vs EF86. There was even a 0.3amp heater version for TV sets. The PF83. http://www.radiomuseum.org/tubes/tube_pf83.html The vari-mu EF89 was used as the audio amplier in some record player amplifiers. DFWB.