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Old 9th Apr 2017, 8:09 pm   #1
Alan Jones
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Smile Acorn valve 954 kits 1960's

When I was in my late teens in the 1960's I bought a 954 'acorn' valve radio kit from a company called 'Olivers' of East London.
It had plug-in coils and could be expanded from 2 to 3 to 4 valves I believe.
It was a great little kit, with everything supplied, even the metal chassis (ready punched) and a separate mains plug-in power supply , I believe.
It came with a front panel which was marked off with a tuning dial.
This kit could get good MW and SW according to the coil inserted.
Does anyone remember this kit?
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Old 9th Apr 2017, 8:22 pm   #2
Ed_Dinning
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Default Re: Acorn valve 954 kits 1960's

Hi Alan, there was an article published in PW I think about a set of this type. This kit may have been a semi commercial version of it.
One of the forum members may remember it and can give you a reference.

Ed
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Old 10th Apr 2017, 9:24 pm   #3
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Default Re: Acorn valve 954 kits 1960's

Hi Alan
I remember these kits very well. They were sold by a small business called RCS Products, 11 Oliver Road, Walthamstow. E17. They usually advertised in Radio Constructor magazine.
There was an article in March 1964 Practical Wireless using the 954 and 955 acorn valves.
Hope this helps


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Old 12th Apr 2017, 5:14 pm   #4
Alan Jones
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Default Re: Acorn valve 954 kits 1960's

Hi folks

Thanks for your replies. Yes Horris the name RCS ltd. certainly rings a bell. I knew 'Oliver' came along somewhere but obviously got it mixed up (my old grey cells are not what they used to be).
This is really good information so I will try and get some pictures and technical info. if I can from somewhere.
After making up this kit (which I seem to remember was not the most expensive option as it had no speaker o/p and headphones were used), I eventually got hold of an old radiogram chassis which had decent LW, MW and SW.

Alan
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Old 12th Apr 2017, 6:07 pm   #5
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Default Re: Acorn valve 954 kits 1960's

My impression is that Acorn valves are still readily available on-line, though the holders for them seem less common. I think it is possible to solder directly to the valve pins.

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Old 12th Apr 2017, 6:33 pm   #6
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Default Re: Acorn valve 954 kits 1960's

Back in 1959, I built one of the portable RCS kits, which you could get in either the one valve or two valve version, using acorn valves like the one at this link:

http://vintageradio.me.uk/kits/rcsport.htm

That isn't the one that prompted this thread, which as I recall, was covered in an R.B article in recent years, where someone created a reconstruction.

The reason they used acorn valves was because they were so cheap and plentiful as the world was awash with countless millions of ex US war surplus acorns. They're charming little valves designed in the mid 1930s particularly for VHF use as being so small, they have very low inter-electrode capacitance. However, the heater was 6.3V at 150 mA so the valve was a very poor choice for battery operation. In fact the bulk of the space in the metal case was taken up by four 'U2' valves as they were then known, to supply the heaters. The batteries lasted only a few hours - rather like leaving a torch switched on in terms of current consumption. That was six times the consumption of the filament of a typical battery valve as used in portable radios of the era - something like a B7G DK96, which had a consumption of only 25 mA.

At least the Acorn valves used only modest HT current - about 2mA, so the hearing aid HT battery lasted quite a while.

Through today's eyes, the kit may seem cheap at 35 shillings (£1.75), but it certainly wasn't - it equates to £37.00 today when adjusted for inflation. At the time, I was a senior apprentice working lots of overtime and saving up to fund a cycling tour of Switzerland and Italy in September that year with two workmates, so I blew some of my savings on the 2-valve kit. It performed really very well, but as the set was switched on by plugging in the headphones (with a jumper across two pins of a 4-pin socket), you had to remember to unplug the phones when not in use.

Later that year, at the end of our three week cycling spree of Switzerland, at Geneva Airport on our way home, in the airport shop, we were amazed to see dinky Hitachi pocket portables with neat leather cases for £9.00, so blew every last penny on one each. Really nothing like it from UK makers at the time, so the writing was on the wall, albeit the sound reproduction from the tiny speaker didn't come close to a Bush TR82, but then the TR82 wasn't designed to fit in a pocket!

I've got some acorn valves and a half built 3-valve TRF, which one day, I might get round to finishing.
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Old 12th Apr 2017, 9:06 pm   #7
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Default Re: Acorn valve 954 kits 1960's

There are some Acorns with 1.5V filaments; they were used in battery-powered walky-talky sets for the US military.

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Old 12th Apr 2017, 9:24 pm   #8
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Default Re: Acorn valve 954 kits 1960's

Did these kits include bases and the little clips for the 'top-cap' connections? I seem to remember bases being hard to find and expensive in the 60's. I built an acorn 'one valver' as a teenager back then, but had to bodge it by soldering direct to the valve pins , which I never liked. I then upgraded it to a DF91 with a base, much tidier!
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Old 13th Apr 2017, 6:31 pm   #9
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Default Re: Acorn valve 954 kits 1960's

One of the big issues with Acorns which led to them being deprecated for military stuff from the very-very-early-1940s was that the act of pushing them into their bases often led to 'micro-fracturing' of the lead-to-glass seals allowing creeping air ingress and subsequent loss-of-vacuum. A lot of what was learned from building Acorns was subsequently put to very good use in developing the B7G/B9A valves.

I recall an Acorn-based VHF receiver-kit being advertised in various rasio magazines in the early-1960s.
It could be built to cover the VHF airband, amongst others. And it was a super-regen. The potential effects of someone using one of these on the viewing-terrace at an airport are best only imagined.
I've got a 1.4V-battery-heater Acorn somewhere in my collection: I'm kinda tempted to dust it off and see if it still does anything.
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Old 13th Apr 2017, 6:32 pm   #10
Alan Jones
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Smile Re: Acorn valve 954 kits 1960's

Hi everybody.
The RCS kit did supply the acorn valve holders and the little clips for the top connection.
I can't remember what the filament current was but the voltage was 6.3 volts.

It was quite a cute little valve but I was always worried that if I had to remove it from the valve holder the glass may get chipped and lose the vacuum, especially as most of the pins were around the 'waist'.

I also remember the portable hand-held radio kit using acorn valves being advertised and was quite tempted to buy one but went for the 'bench' model instead.

Thanks for all your input.

Alan
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Old 18th Apr 2017, 11:51 am   #11
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Default Re: Acorn valve 954 kits 1960's

I read it was a BAD practise to solder to the pins.
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Old 18th Apr 2017, 2:16 pm   #12
M0FYA Andy
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Default Re: Acorn valve 954 kits 1960's

I agree that it can only be bad practice, risking damage. It also looks a mess!

But certainly fitting and removing them from a proper base is a bit fraught. I've certainly caused damage, especially removing a valve in an awkward installation.

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Old 18th Apr 2017, 6:03 pm   #13
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Default Re: Acorn valve 954 kits 1960's

Another use for scavenged D-Type connector inserts?
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Old 18th Apr 2017, 9:02 pm   #14
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Default Re: Acorn valve 954 kits 1960's

Hi Gents, RS used to do some nice insulated 1mm sockets. These fitted the pins of acorn valves nicely.

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Old 18th Apr 2017, 11:36 pm   #15
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Default Re: Acorn valve 954 kits 1960's

A lot of British professional electronics used to use "handbag" plug links to change/select circuit elements on PCBs- these went into gold-plated brass PCB sockets, sort of like individual turned-pin IC sockets but bigger. If only I could think of the proper name for them, there's probably a few million in a disposal site somewhere. They'd probably work with acorn pins.
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Old 19th Apr 2017, 3:02 am   #16
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Default Re: Acorn valve 954 kits 1960's

So, the original socket poses a mechanical risk and soldering with conventional solder poses a thermal risk. Maybe an opportunity to use a bit of Wood's metal as solder (Mpt ~70'C)?

Whatever the pin material is on Acorns, I've seen some NOS RCA ones which came out of their boxes with really badly tarnished pins.

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Old 19th Apr 2017, 9:07 am   #17
M0FYA Andy
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Default Re: Acorn valve 954 kits 1960's

I think that soldering directly to the pins is a bodge, and looks like a bodge, even if low temperature solder eliminates damage.
Modern aircraft circular connectors use removable pins and 'socket pins', I have some scrounged during my working life. I wonder if they are readily available?
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Old 22nd Apr 2017, 11:32 pm   #18
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Default Re: Acorn valve 954 kits 1960's

One possible way of utilising an Acorn might be to "drop" the glass envelope through a hole in a PCB, so that the pins sit on appropriately sized/located copper tracks. I think a "SMD Acorn valve" sounds like an interesting proposition

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Old 23rd Apr 2017, 12:05 am   #19
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Default Re: Acorn valve 954 kits 1960's

Sort of like the PCB mounting method for "pill" package UHF transistors? I'd want slots machined in the GRP PCB material around the lands (like the primary side-to-secondary side anti-creepage slots in SMPSU PCBs) to give a bit of flexure around the valve-pins. Otherwise, I could imagine thermal cycling and over-stiff PCB giving problems.
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Old 23rd Apr 2017, 1:44 am   #20
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Default Re: Acorn valve 954 kits 1960's

Yes, some consdieration of thermal stress might be needed for the 6.3V heater versions, but the 1.5V valves should sidestep that propblem.

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