EL85 Valve. Usage? - UK Vintage Radio Repair and Restoration Discussion Forum

flyingtech55 · 7th Jun 2020, 4:01 pm

Anybody any idea what set/sets used the EL85 valve? I've found a box of three new ones but can't think of what they were used for.

TimR

Cobaltblue · 7th Jun 2020, 4:13 pm

Not a commonly used valve but at least one set used it

https://www.radiomuseum.org/r/hismasters_1623.html

I think it more often appeared in commercial equipment.

Cheers

Mike T

GrimJosef · 7th Jun 2020, 4:16 pm

The valve museum entry gives some guidance about what Mullard expected it to be used for http://www.r-type.org/exhib/aaa0226.htm but whether it actually was used for this I don't know.

Cheers,

GJ

turretslug · 7th Jun 2020, 4:54 pm

Supposedly part of the long-running low heater power family that went EL2, EL32, EL42, EL95, ISTR that the difference between it and EL95 was that the 9-pin base meant that the suppressor grid and cathode connection could be separated, which suited it better for RF PA-type applications. Once the EL42 goes extinct, it could be a retro-fit candidate!

barrymagrec · 7th Jun 2020, 5:07 pm

The 200mA heater made it handy to use with an EF86 for a low power audio amp for systems using 12 volt heater supplies such as vehicles and Leevers Rich tape machines.

sentinel040 · 10th Jun 2020, 9:54 pm

It was used in the transmitter mutiplier stages of some early 1960's Hudson mobile two-way radios.

Ian

G6Tanuki · 11th Jun 2020, 2:27 pm

Quote:

Originally Posted by sentinel040

It was used in the transmitter mutiplier stages of some early 1960's Hudson mobile two-way radios.

Ian

I've also seen - in a military-airband transceiver - a pair of them in Class-A push-pull as modulator, with a QQV02/6 as the PA. Five watts of RF don't need much AF to give 100%+ "speech quality" modulation, and two EL85 take up less space/need less heater-power than something like a pair of 6V6.

Chris55000 · 11th Jun 2020, 8:54 pm

Hi!

There are, in fact, enough pins on the B8A Rimlock.base to provide s separately pinned suppressor–grid connection (the EF40, EF42 and EAF42 diode/pentode all had separately pinned suppressor grids, so theoretically, you could make a single–ended power output valve with a separately pinned G3 for r.f. power amplifiers, but I don't think any valve–manufacturer actually did so!

Chris Williams

Robert Gribnau · 12th Jun 2020, 10:34 am

The EL43 and EL44 have seperate suppressor-grid connections.

https://frank.pocnet.net/short/054/2/218.pdf

https://frank.pocnet.net/short/054/2/213.pdf

Peter.N. · 12th Jun 2020, 11:38 am

I was about to say that I had never seen an EL85 until Ian mentioned Hudson PMRs. I used to maintain a number of those in the '60s for the local garage's FX4 Taxi fleet - so I must of done, obviously never had to change one.

Peter

barrymagrec · 12th Jun 2020, 12:20 pm

I never replaced one in a Leevers Rich either - that`s why I have several NOS in the loft.

livewireless123 · 13th Jun 2020, 10:27 am

I think the el85 was/is mainly a low power rf valve. there were two in the PYE
ptc 114 early pmr rig from the 50s I used the tx as my first 70MHz am rig
it had an ef91 Xtal osc,two el85 as multiplier and driver to an 832 PA
The modulator was two 6v6gt and a carbon mic, I added a pre-amp for a crystal mic. it's been scrapped long ago but I still have the Mod transformer built into another Transmitter.

Paul Stenning · 13th Jun 2020, 10:34 am

I scanned the Mullard data for that valve the other day. Attached.

7th Jun 2020, 4:01 pm	#1
flyingtech55 Octode Join Date: Nov 2005 Location: Ayrshire, UK. Posts: 1,096	EL85 Valve. Usage? Anybody any idea what set/sets used the EL85 valve? I've found a box of three new ones but can't think of what they were used for. TimR __________________ All those moments will be lost in time, like tears in rain. Last edited by flyingtech55; 7th Jun 2020 at 4:02 pm. Reason: Typo

7th Jun 2020, 4:13 pm	#2
Cobaltblue Moderator Join Date: Dec 2010 Location: Exeter, Devon and Poole, Dorset UK. Posts: 6,857	Re: El85 Not a commonly used valve but at least one set used it https://www.radiomuseum.org/r/hismasters_1623.html I think it more often appeared in commercial equipment. Cheers Mike T __________________ Invisible airwaves crackle with life or at least they used to Mike T BVWS member. www.cossor.co.uk

7th Jun 2020, 4:16 pm	#3
GrimJosef Dekatron Join Date: Sep 2007 Location: Oxfordshire, UK. Posts: 4,311	Re: El85 The valve museum entry gives some guidance about what Mullard expected it to be used for http://www.r-type.org/exhib/aaa0226.htm but whether it actually was used for this I don't know. Cheers, GJ __________________ http://www.ampregen.com

7th Jun 2020, 4:54 pm	#4
turretslug Dekatron Join Date: Nov 2011 Location: Surrey, UK. Posts: 4,393	Re: EL85 Valve. Usage? Supposedly part of the long-running low heater power family that went EL2, EL32, EL42, EL95, ISTR that the difference between it and EL95 was that the 9-pin base meant that the suppressor grid and cathode connection could be separated, which suited it better for RF PA-type applications. Once the EL42 goes extinct, it could be a retro-fit candidate!

7th Jun 2020, 5:07 pm	#5
barrymagrec Octode Join Date: Dec 2017 Location: Morden, Surrey, UK. Posts: 1,557	Re: EL85 Valve. Usage? The 200mA heater made it handy to use with an EF86 for a low power audio amp for systems using 12 volt heater supplies such as vehicles and Leevers Rich tape machines.

10th Jun 2020, 9:54 pm	#6
sentinel040 Hexode Join Date: Feb 2007 Location: Near Lichfield, Staffordshire, UK, most of the time and Crystal Palace, S London, some of the time.. Posts: 330	Re: EL85 Valve. Usage? It was used in the transmitter mutiplier stages of some early 1960's Hudson mobile two-way radios. Ian

11th Jun 2020, 8:54 pm	#8
Chris55000 Nonode Join Date: Aug 2007 Location: Walsall Wood, Aldridge, Walsall, UK. Posts: 2,864	Re: EL85 Valve. Usage? Hi! There are, in fact, enough pins on the B8A Rimlock.base to provide s separately pinned suppressor–grid connection (the EF40, EF42 and EAF42 diode/pentode all had separately pinned suppressor grids, so theoretically, you could make a single–ended power output valve with a separately pinned G3 for r.f. power amplifiers, but I don't think any valve–manufacturer actually did so! Chris Williams __________________ It's an enigma, that's what it is! This thing's not fixed because it doesn't want to be fixed!

12th Jun 2020, 10:34 am	#9
Robert Gribnau Heptode Join Date: May 2017 Location: Konongo, Ghana Posts: 513	Re: EL85 Valve. Usage? The EL43 and EL44 have seperate suppressor-grid connections. https://frank.pocnet.net/short/054/2/218.pdf https://frank.pocnet.net/short/054/2/213.pdf

12th Jun 2020, 11:38 am	#10
Peter.N. Dekatron Join Date: Jul 2008 Location: Charmouth, Dorset, UK. Posts: 3,601	Re: EL85 Valve. Usage? I was about to say that I had never seen an EL85 until Ian mentioned Hudson PMRs. I used to maintain a number of those in the '60s for the local garage's FX4 Taxi fleet - so I must of done, obviously never had to change one. Peter

12th Jun 2020, 12:20 pm	#11
barrymagrec Octode Join Date: Dec 2017 Location: Morden, Surrey, UK. Posts: 1,557	Re: EL85 Valve. Usage? I never replaced one in a Leevers Rich either - that`s why I have several NOS in the loft.

13th Jun 2020, 10:27 am	#12
livewireless123 Tetrode Join Date: Jul 2018 Location: Southport, Merseyside, UK. Posts: 63	Re: EL85 Valve. Usage? I think the el85 was/is mainly a low power rf valve. there were two in the PYE ptc 114 early pmr rig from the 50s I used the tx as my first 70MHz am rig it had an ef91 Xtal osc,two el85 as multiplier and driver to an 832 PA The modulator was two 6v6gt and a carbon mic, I added a pre-amp for a crystal mic. it's been scrapped long ago but I still have the Mod transformer built into another Transmitter. __________________ HAPPINESS IS A WARM WIRELESS PREVIOUS USER NAME- MIKE G3ZII