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Components and Circuits For discussions about component types, alternatives and availability, circuit configurations and modifications etc. Discussions here should be of a general nature and not about specific sets. |
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7th Jun 2020, 4:01 pm | #1 |
Octode
Join Date: Nov 2005
Location: Ayrshire, UK.
Posts: 1,096
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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
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7th Jun 2020, 4:13 pm | #2 |
Moderator
Join Date: Dec 2010
Location: Exeter, Devon and Poole, Dorset UK.
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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
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7th Jun 2020, 4:16 pm | #3 |
Dekatron
Join Date: Sep 2007
Location: Oxfordshire, UK.
Posts: 4,311
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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
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7th Jun 2020, 4:54 pm | #4 |
Dekatron
Join Date: Nov 2011
Location: Surrey, UK.
Posts: 4,400
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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!
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7th Jun 2020, 5:07 pm | #5 |
Octode
Join Date: Dec 2017
Location: Morden, Surrey, UK.
Posts: 1,562
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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.
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10th Jun 2020, 9:54 pm | #6 |
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
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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, 2:27 pm | #7 |
Dekatron
Join Date: Apr 2012
Location: Wiltshire, UK.
Posts: 14,010
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Re: EL85 Valve. Usage?
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.
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11th Jun 2020, 8:54 pm | #8 |
Nonode
Join Date: Aug 2007
Location: Walsall Wood, Aldridge, Walsall, UK.
Posts: 2,874
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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
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12th Jun 2020, 10:34 am | #9 |
Heptode
Join Date: May 2017
Location: Konongo, Ghana
Posts: 516
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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 |
Dekatron
Join Date: Jul 2008
Location: Charmouth, Dorset, UK.
Posts: 3,601
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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 |
Octode
Join Date: Dec 2017
Location: Morden, Surrey, UK.
Posts: 1,562
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Re: EL85 Valve. Usage?
I never replaced one in a Leevers Rich either - that`s why I have several NOS in the loft.
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13th Jun 2020, 10:27 am | #12 |
Tetrode
Join Date: Jul 2018
Location: Southport, Merseyside, UK.
Posts: 63
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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.
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