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Homemade B5 valveholder

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Homemade B5 valveholder

Post by Sparks » Tue May 03, 2016 2:39 pm

I wanted a baseboard B5 valveholder, so decided to make one. This is made from two pieces of brown acrylic sheet cut into circles with a round saw. The sockets are brass tubes from a model shop with the top ends opened out a bit by getting them red hot, putting a centre punch in them and giving a sharp tap with a hammer. I then glued them into the holes with Gorilla superglue. The five connection bolts had five thin wires soldered to them before fitting in the holder. The wires were wrapped round the tubes underneath, and soldered. The tubes protrude beneath the valveholder, but this is accommodated by drilling a large round hole where the valveholder is to be fitted, using a wood-cutting bit!
Very pleased with the result.
Bob
Attachments
B5 Valveholder (Large).JPG
Valve Holder

 
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Re: Homemade B5 valveholder

Post by Ed Dinning » Tue May 03, 2016 8:49 pm

Hi Sparks, well worthy of the home builders of the 20's. The dimensions for the popular sizes of valveholders with pin spacings were given in various PW books, but it was also possible to buy them made our of brass tube and with a thread on the open end so they could be screwed into the baseboard and a wire soldered on underneath.


Ed

 
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Re: Homemade B5 valveholder

Post by Sparks » Tue May 03, 2016 9:20 pm

Thanks Ed,
I got the pin spaciing by rubbing the pins of a 5 pin valve on a sheet of wet & dry paper to make them all flat, and the same level. I then put a spot of black water paint on the end of each pin, and "printed" them on a sheet of acrylic. I sawed out the top disk using the centre hole as the pilot for the round saw in the drill press. It took about an hour to make the valveholder, but I will no doubt speed up on the next one! Making chassis mounting B4 and B5 holders is a lot quicker!
Bob

 
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Re: Homemade B5 valveholder

Post by Michael Watterson » Wed May 04, 2016 5:48 pm

Much nicer than the B4 ones I have made for battery packs, out of coffee tin and white margarine tub! (The AD3, B103, B136, B137 all use B4).

 
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Re: Homemade B5 valveholder

Post by Ed Dinning » Wed May 04, 2016 8:27 pm

Hi Bob, if you PM me your e-mail I'll send you a scan of the various valve base dimensions in the PW books. (Just in case you need to go to B7, B9 etc)

Ed

 
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Re: Homemade B5 valveholder

Post by Sparks » Wed May 04, 2016 8:55 pm

It's OK thanks, Ed, I have the B7 in old full-size blueprints. As for B9, I don't have any B9 valves, so unlikely I would want to make one. It is just that I have quite a large quantity of B4 and B5 valves built up over many the years, and felt like making a 3 valve battery TRF. I am not as interested in B7 valves, although I have a few. I did have quite a number of baseboard B4 and B5 valveholders, but they were all different makes, so I sold them on Ebay some time ago when I dscovered that I could make them myself without much trouble!
Bob

 
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Re: Homemade B5 valveholder

Post by Greenstar » Sat May 14, 2016 7:53 pm

I'm impressed. I had a go making B4 valveholders and used a similar method to give the socket positions. I found in a couple of attempts the valve would only just fit, and tended to put strain on the pins which wouldn't go fully in. It seemed a higher level of accuracy was needed. I made a couple that work, but they weren't very satisfactory. Like Michael I rolled my sockets from tin plate, maybe these would have been better a little larger.

Tony

 
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Re: Homemade B5 valveholder

Post by Sparks » Sat May 14, 2016 9:28 pm

The brass tubes are slightly larger than the valve pins, and are quite loose when slid on separately. I felt that the slight innacuracies of drilling the holes would work to my avantage causing each valve pin to come into good firm contain with at least part of each tube. This has proved to be the case. The valve is a good fit, but not too tight, in the holder. Drilling the holes was quite easy with a drill press. It would have been rather more difficult with a hand drill!
Bob

 
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Re: Homemade B5 valveholder

Post by Greenstar » Mon May 16, 2016 7:32 am

Bob, can you think what size tubing you used? I rolled the plate around a drill bit, but was aiming for a tight fit. Good idea to loosen it up. Must get my self a proper drill press too. I have one of those that hold a hand power drill, but it tends to move.

 
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Re: Homemade B5 valveholder

Post by Sparks » Mon May 16, 2016 9:39 am

It appears to be 3mm internal diameter. I got it from Homebase DIY, but they don't stock it anymore in Presron. I have also seen it at B&Q, but have not been there for some time. You can usually get 1 foot lengths from model shops. I took a valve along with me so I could try it for a satisfactory fit before purchasing it.
I can recommend a drill press, because you can cut round pieces of acrylic with a circular cutter. I used it to make the bases. The drill press is one of my most usefl tools!
Bob

 
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Re: Homemade B5 valveholder

Post by Terrykc » Wed May 18, 2016 3:32 pm

All the dimensions you want for accurate pin spacing are here:

Image

Wikipedia gives the pin diameter as 3.2mm and the hole diameter - based on the drawings - would appear to be (B-C)*2 = 4.05mm, so presumably 4mm OD tube is used.

 
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Re: Homemade B5 valveholder

Post by Sparks » Wed May 18, 2016 4:32 pm

Thanks, but I already had the spacing in the Practical Wireless Encyclopaedia, F. J. Camm. Perfect accuracy is not really desireable when making my own. Although I drill the holes as accurately as I can (by eye), with each one being very slightly off, ensures that the pins come into good contact with the brass tubes at some point.
I was going to put the following in my 3 Valve TRF construction article in the Radio & Audio section, but as there is more interest in the valve-holders here, put it here!
-----------------------
I am now well-advanced in the construction of three valve-holders, two B4 and one B5. The six disks have been cut from 4mm black acrylic using a round saw in the drill press. At present, they are bolted together temporarily whilst the glue dries. The next task will be to fit the 13 brass tubes, and then the terminals and wiring from them to the brass inserts. I obtained the tubes from a model shop, see attached.
Bob
Attachments
8 Brass tube - Copy (Medium).JPG
Brass tube
15 Ready for metalwork - Copy (Medium).JPG
Ready for metalwork

 
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Re: Homemade B5 valveholder

Post by crackle » Wed May 18, 2016 10:06 pm

Hi Bob
Dont mistake a lack of replies to your thread as a lack of interest.
I am sure many people are following your creative endeavours with fascination.

Mike

 
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Re: Homemade B5 valveholder

Post by Sparks » Thu May 19, 2016 7:15 am

Mike,
It is rather like "playing to an empty theatre," sometimes :cch I don't need to be showered with praise or anything, and it is often refreshing to be told I don't know what I am talking about! :aaj The only thing that bores me out of my mind is when incessant "theory" gets quoted to me :bbc. I often feel like a "lone dinasaur" plodding my way to extinction! :ccf I know it is more sensible to purchase a B5 valveholder if I want one, but half the fun of it is making my own! In my reproduction vintage TRF build, I was hoping for some views and discussion about the rather odd tuning arrangement of the RF amplifier, V1. I have no idea why it works so well, after discovering it by accident! http://www.forum.radios-tv.co.uk/viewtopic.php?f=3&t=13154
Bob

 
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Re: Homemade B5 valveholder

Post by rob t » Thu May 19, 2016 10:27 am

I second what mike said .
i am loving this thread but have nothing useful to add as i have never tried to do anything like it.
Having said that i intend to nick your idea of using brass tube to make reproduction batteries for the likes of vidor ect radios
Rob T

 
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Re: Homemade B5 valveholder

Post by Katie Bush » Thu May 19, 2016 3:11 pm

Ditto to both the above. :bba

I'm more telly orientated than radio, but I still find threads like this very interesting.. TRF was long before my time, and in all fairness, I've never met a TRF set in my life.

I once tried to build a crystal set, with help from my granddad, but could never get it to work.. I can however see the similarities in the 'front end' circuitry you have here.

In one sense, I can't really add anything since I don't really know anything, but it's interesting to learn. :aad

What I do like, is the 'belt n' braces' aspect - I'm decidedly dim in the theory department, but can (or could) get stuck in on the practical stuff. :)

Marion


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