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Old 16th Jun 2022, 6:30 am   #21
Robert Gribnau
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Default Re: Valve substitution question can an EF86 replace an EF804?

One could consider a PF86 as a replacement for an EF86. Except for the heater requirements, they are equivalent. Prices for a NOS PF86 are from 3 Euro (2,5 Pounds) going in The Netherlands.

You would only need to place a resistor of around 6 Ohm in one of the leads to the heater pins (or two resistor of about 3 Ohm, one in each of the leads to the heater pins). The heater current draw will be 0,3 A instead of 0,2 A but that small difference will not be a problem in most, if not all cases.

The PF86 was used in earlier televisions as a transitron oscillator. Philips used the PF86 instead of the EF86 in a batch of their AG7600 organ amplifiers, probably to get rid of surplus PF86's.
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Old 16th Jun 2022, 9:50 am   #22
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Default Re: Valve substitution question can an EF86 replace an EF804?

Another example is with the EL84 (6BQ5), which also command high prices for NOS - I would say £30 is the going rate nowadays for a Philips Miniwatt. Currently you can pick up RCA 8BQ5 or 10BQ5 for less than £8 each.

Also ECC82 (12AU7) - my local auction site has RCA 7AU7 for £3.50 each, multiple purchases possible.
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Old 16th Jun 2022, 10:47 am   #23
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Default Re: Valve substitution question can an EF86 replace an EF804?

Also UF86, if you are running a 12 volt heater supply, which is quite a good scheme anyway.
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Old 16th Jun 2022, 11:14 am   #24
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Default Re: Valve substitution question can an EF86 replace an EF804?

But ... all this brings me back to my original point about having a centralised repository of what tubes are held privately, to give developers confidence that spare tubes could be available down the line. The heater wiring is the first thing that is completed for a point to point constructed amplifier, so it is the hardest to chop and change, which steers people away from these great tubes. Likewise PCB designers could support different heater voltages for some tubes, and even support alternate pin layouts for electrically similar tubes.

The larger tubes are easier to accomodate. The paxolin loctal sockets fit exactly on a octal base, so using 5B/254M in my quad was just to map the connections. Also an AX4 with side contacts can be permanently fitted into an octal base, to sub for a 5AR4 but with a 4V filament.

The goal is to give a lease of life for any old tube, although the Hexodes, Heptodes, Octodes and Thyratrons will be unusable, I think.

I have seen a circuit for an Octode which uses different combinations of grids independently, for audio, and also I have a phase splitter based on the heptode part of an ECH21 I am keen to try.
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Old 16th Jun 2022, 12:39 pm   #25
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Default Re: Valve substitution question can an EF86 replace an EF804?

Regarding the "using valves for new builds v's keeping said valves for radio TV restoration" argument 1) the majority of radio/TV valves have no application in hifi/guitar amps apart from the final OP's that is. 2) The stocks of hexodes, multi function and radio specific valves are far likely to outlast the stock of vintage radio & TV restorers, the latter being of a similar vintage and have built in obsolescence. Sad but true.

Re EF804's Billington have them the "Grade 1's" being cheaper @ £15 rather £26, something to do with the colour of the print?

Andy.
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Old 16th Jun 2022, 1:35 pm   #26
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Default Re: Valve substitution question can an EF86 replace an EF804?

They are used.

Grade One valves are slightly used items of best physical appearance.
Unless stated otherwise they have small stains in the glass. Stains may also mean small imperfections to
getter, base, etc.
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Old 16th Jun 2022, 2:57 pm   #27
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Default Re: Valve substitution question can an EF86 replace an EF804?

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But ... all this brings me back to my original point about having a centralised repository of what tubes are held privately, to give developers confidence that spare tubes could be available down the line.
The problem with such 'repositories' is that they take time and effort to create, then time and effort to maintain.

Both of which imply that there would need to be funding to cover these costs. And that in turn leads to a whole slew of legal/contractual issues.

Do people wanting to list their collections pay these costs?

Or do those wanting to find valves pay a 'search fee'? [and would that be refunded if your search failed to find a match?]

What happens when the 'custodian' of the repository's database dies/forgets-to-renew-the-domain-registration/decides-to-sell-it-as-a-profitable-business to some speculatory interest, who find it doesn't generate a decent profit, lose interest and abandon it?

Perhaps a role for blockchain technology? But, again, who will fund it?


Personally, I find the likes of Ebay to be the best source, which has both 'reach' and 'range'. And regarding the EF86, couldn't you just use an EF80 or EF85 instead? I've done loads of seemingly ill-advised valve-substitutions in the past, sometimes with a bit of fiddling of the cathode-bias resistor, but it's amazing what you can get away with.
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Old 16th Jun 2022, 6:02 pm   #28
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Default Re: Valve substitution question can an EF86 replace an EF804?

Quote:
But ... all this brings me back to my original point about having a centralised repository of what tubes are held privately, to give developers confidence that spare tubes could be available down the line.
A couple of weeks ago I asked on the forum about how to sensibly dispose of my collection once I went to the great workshop in the sky. This includes my collection of valves, amongst them some fairly popular double triodes and a few NOS magic eyes. My relatives dealing with disposing of my household are not going to want to selll individual valves. Also, I would like them to go to people who genuinely need them rather than looking for a quick buck.

Now to my question, would the BVWS or similar orgainsation be willing to handle these and dispose of them in the best possible manner? I realise it would mean a lot of work for the volunteers concerned. I suppose the other option would be for the BVWS to auction them as a job lot. Not really what I want, being a cynic, I would fear them turning up on some auction site for big money.

Just my two cents worth, what do other members think?
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Old 17th Jun 2022, 6:24 am   #29
Robert Gribnau
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Default Re: Valve substitution question can an EF86 replace an EF804?

I own more than 1100 NOS valves and close to 2000 used valves (about 1500 of them are tested). Almost all are usable for audio.

My wife (Ghanian) and I are going to emigrate to Ghana in a couple of months. The demand for valves in and around Ghana will be (close to) zero. I really hate the idea of my valves and other parts just withering away overthere after I die so I'm going to teach one or two family members in Ghana how to sell valves and other parts through the internet, preferably through an adress in Europe as not to scare off potential buyers (would you buy valves from an adress in Ghana?).

I kept good records of my valves (with factory codes and all) but I didn't add the (estimated) prices yet, so that is still on my to do list.
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Old 17th Jun 2022, 7:08 am   #30
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Default Re: Valve substitution question can an EF86 replace an EF804?

The last two posts are highly indicative of most of the members here.
I like the idea!, but then I am generous ( so the wife says ).
I have a list of direct alternatives to most BIG audio valves, alas there isnt much to replace the early twin triodes, or more modern twin triodes, but sooner or later one of the profiteers will cotton on to what can be substituted. For any member here that "needs " big audio bottles I will gladly supply a list,

BUT Ifn I doan nose ya, no sir I aint got none.

MOST of my substitutes require a change of valve base to suit.
THAT renders the chood rollers useless as many dont know ( or understand ) the rarer bases, or, for that matter, valves with top caps. OHH !! and it has NOTHING to do with the brand of strings you use!!.

To some extent, maybe its better that we DONT serve out valves to all and sundry ?.
But somebody mentioned that TRUE home builders that actually study the art, need some help.
Do we introduce " Non disclosure " agreements that are court enforceable ?.

Starting to attack my own logic !!.
To quote uncle frank: Aint this boogie a mess ?.

Joe
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Old 17th Jun 2022, 8:26 am   #31
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Default Re: Valve substitution question can an EF86 replace an EF804?

As with Joe, I would think the easiest thing is to keep an inventory of one's own valves, and use common sense about who to supply them to, rather than actually publishing lists, which will need maintaining. This forum is an excellent means to make requests for parts. It is also something we all have to face to make arrangements for the survival of our stuff after our own current lifetimes! Having said that, my own spares are a hopeless jumble ... that is the problem.
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Old 17th Jun 2022, 12:45 pm   #32
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Default Re: Valve substitution question can an EF86 replace an EF804?

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Originally Posted by Richardgr View Post

Just imagine a similar site for everything electrical! You need sme 5W wire wound resistors - you enter the search Component=Resistors, Power=5W, Resistance= 10R-15R, hit enter ... whoa, look at all those entries! I prefer wirewound, add criteria for composition, and see that the nearest person with a resistor like that to you in Alice Springs is a certain Joe Bog. The price is right, the job's a good'un.
That could be a very nice system. In case of hobby collections, you would have to make provisions for collections that go "silent", i.e. the curator gets hospitalised, admitted in a care home or dies. In such a case, the stock should go to a central warehouse or another close by curator for a pre-determined sum (if not pre-determined it would realistically be around 10% of retail value, depending on the exact mix of goods).

I'm in the business of vintage parts for half a year now, initially to clear out my fathers and my own stocks that would last me several lifetimes but I acquired some parts stashes along the way as well and now I'm aiming to make it one of three main hobby/business goals.

I could see myself implementing some kind of parts exchange as described above somewhere down the line as well, but for now acquisition and commission seem the most feasible.
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Old 18th Jun 2022, 2:55 pm   #33
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Default Re: Valve substitution question can an EF86 replace an EF804?

Hello,

I did this post as part of a reply to another thread, and I feel it could be applicable to the EF86 replacement thread as well as the EF36 is a precursor to the EF86.

I’ve recently made an EL84 amplifier using an EF184 and a E180F. It uses the Jefferey, High Gain, Push-Pull Phase-Splitter circuit, which originally used EF36's. It used a triode connected EF184 as the phase splitter and a E180F as the first stage (voltage amplifier). It works well; however, it has the short coming of the Jeffrey design, but personally this don’t cause any problems in practice.

Keeping with the continued reuse of parts and not just having them sitting gathering dust on the shelf these amplifiers were made using transformers and parts from the parts stash. It also gave me chance to try different valves.

Terry
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Old 18th Jun 2022, 8:31 pm   #34
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Default Re: Valve substitution question can an EF86 replace an EF804?

I think the biggest problem for the European tyro is the lack of transformer parts. I have a tea-chest arc welder my grandfather made, I guess in the 1940s. He wound the transformers himself, as he did for various projects.

I know only the most basic valve theory, but have managed to make a few amplifiers from known circuits, and have plotted loadlines for bizarre Soviet valves as I fried my brain reading Morgan Jones and planned circuits. However, I haven't any of the knowledge the esteemed members here have about different valve types, and find the biggest barrier to the sort of experimentation of my grandfather's generation is the transformer, not the valve. It appears laminations and so on are what used to be available in some local shop with a chain-smoking proprietor, and now there are just boutique suppliers.

The Internet has been a great tool, but it is also a great deadener. I can't be the only one who has been put off an experiment from the endless searching and previous experiences of online afficionados bringing so many possibilities to mind that the original idea seems puerile. The breadth of experience becomes paralysing. From hanging around here, I know many members grew up in a much more experimental era where the lack of information was a spur. A few columns of Cathode Ray and some valves from the telly and away you go - it's an education I admire, and am rather jealous of.
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Old 18th Jun 2022, 9:23 pm   #35
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Default Re: Valve substitution question can an EF86 replace an EF804?

Take some of what is on the internet with a pinch of salt and go for what you think is right and worth having a go at, no matter how puerile you think it might be.

I cut my teeth on guitar amps back in the mid 70’s and there weren’t any boutique suppliers, we built the amps with the parts we could ‘commercially’ get. Why did we use ‘Mustard’ and ‘tropical fish’ capacitors, well, there were piles out there at a decent price and they were of a decent quality – no more no less – defiantly no snake oil stuff.

I now work in the UK hi-fi industry, and I despair at the boutique and snake oil antics in the guitar and hi-fi game – do you know commercial components can work rather well.

That enough for now!

Terry
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Old 19th Jun 2022, 10:56 am   #36
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Default Re: Valve substitution question can an EF86 replace an EF804?

Quote:
Originally Posted by Uncle Bulgaria View Post
I think the biggest problem for the European tyro is the lack of transformer parts. ...

The Internet has been a great tool, but it is also a great deadener. I can't be the only one who has been put off an experiment from the endless searching and previous experiences of online afficionados bringing so many possibilities to mind that the original idea seems puerile. ...
On the subject of transformers, there are some quite reasonable and excellent performing contenders available today. You have Majestic in the UK, but I have used a lot of Toroidy products. Hammond does a cheap SE transformer that can be configured for different anode loads, to encourage experimentation.

I get your drift regarding the internet resources, but on the other hand do we want to re-invent the wheel all the time, and constantly have that committee meeting where we decide what colour it should be? [Hitchikers Guide reference ;-) ]
As previously mentioned, I have a shed load (literally) of around 1200 different flavours of tube, fron the 1920's onwards, but predominantly the 50's (which I consider to be the golden age). I am trying to find worthwhile homes for some of the unloved, and the internet is a supreme resource for that, where I can learn from others attempts, or find obscure commercial schematics where they were used succesfully.
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Old 19th Jun 2022, 7:53 pm   #37
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Default Re: Valve substitution question can an EF86 replace an EF804?

Hi UB, output transformers can be wound from scrap transformers salvaged from old sets.
These will usually be Stalloy lams but if run at about 0.5 T they should sound OK.
Bobbins can easily be fabricated and there are not that many turns required; Wires.co.uk can supply the wire quite reasonably.

Because of safety issues I would only recommend this for output transformers on transformer isolated sets and not to build mains transformers

Ed
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Old 3rd Jul 2022, 12:25 am   #38
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Default Re: Valve substitution question can an EF86 replace an EF804?

So back to my original question - I found these: https://www.ebay.com.au/itm/202286540737

That convert the pin config of an EF86 to that of an EF804. Have installed these in my Tandberg model 5 tape recorder and it's associated lower channel separate amplifier - all working great. I did use two Telefunken EF86s from a junked Magnetophon 97 tape machine.
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Old 3rd Jul 2022, 1:54 am   #39
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Default Re: Valve substitution question can an EF86 replace an EF804?

There are hundreds of "adaptors " available on those auction sites, of varying quality and varying usefulness. The individual "bits " are available at very cheap prices if you want to go thjat way.

I guess thats the easy way to go for those ( very politely ) are for the half educated. Anybody thats been doing this hobby ( or job ) a while would simply rewire a socket or two. Of course there is a reverse engineering view, where someone will stumble on a source of cheap origional replacements.
Then again, there are quite a few valves that will serve in audio duty ( hi-fi or guitar, PA ) which would benefit by a type number and pin swapping upgrade. That wont help newbies I dont think.
It also wont help the guitar fraternity!!. I have been abused and sworn at for replacing leaky grid couplers !!. "yes it doesnt hum anymore and runs much cooler and has more power ", but it sounds like shiyt! Go figure.

If any regular here needs valves at least put up a wanted add in the right section, if I have any I will offer them, especially for radio or TV.

Joe
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