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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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Old 6th Feb 2023, 6:15 pm   #1
Diabolical Artificer
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Default Top cap shortage?

Just tried to order some 3/8"/10mm anode top caps, can't find any for love nor money. Ebay used to be awash with them, no longer the case. I do have a few lesser known sellers bookmarked that have ceramic top caps in stock but the last 10mm caps I bought don't fit 807's etc. I've quite a few EF37A type's, but non that's fit 807's.

Billington's website has none, Langrex only have used bakelite types.

Anyone else had this issue? Andy.
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Old 6th Feb 2023, 7:12 pm   #2
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Default Re: Top cap shortage?

I have made them out of scrap copper pieces
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Old 6th Feb 2023, 11:29 pm   #3
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Default Re: Top cap shortage?

There are some that might do on AliExpress:-

https://www.aliexpress.com/item/32837014928.html?
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Old 6th Feb 2023, 11:59 pm   #4
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Default Re: Top cap shortage?

I might have some ceramic ones. Let me check.

Craig
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Old 7th Feb 2023, 12:25 am   #5
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Default Re: Top cap shortage?

Electols have sold out but Ask Jan First look like they have some.
With Billingtons it is worth calling.
.
Conrad's are not the first company that come to mine, but they have some interesting tube stuff and fair prices. They have 9mm And
10mm caps

Last edited by Richardgr; 7th Feb 2023 at 12:30 am.
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Old 7th Feb 2023, 1:22 am   #6
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Default Re: Top cap shortage?

There's these on ebay
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Old 7th Feb 2023, 8:34 am   #7
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Default Re: Top cap shortage?

I have thought about making them out of hacksaw blades, but making an insulator is difficult, maybe a bottle top filled out with chemical putty or similar?

I've never bought off Aliexpress, what's folks experiences without going into details about specific sellers?

Some good suggestions there Richard, unfortunately both in the EU but Conrads carry some odd stuff, not come across them before. That's a bit too basic for what I need at the mo kalee, but thanks for the heads up anyhoo. Thanks for looking Craig.

It does look like there's less about than there used to be which is a bummer but on the other hand there must be quite a few folk out there messing about with valves.

Andy.
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Old 7th Feb 2023, 10:24 am   #8
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Default Re: Top cap shortage?

Hello Andy,

I have a pair of the Bakelite dark red ‘angled top cap’ type I’ll never use you’re welcome to FOC if it does you a good turn.

I’ve noticed of late the availability of parts is on the decline, or they are not being sold so much via swapmeets, rallies and jumbles etc. This links up a little with the thread Rallies 2023 in Clubs, Groups and Societies.

I suppose there is finite supply of these bits, plus the supply of vintage parts has become more monetized of late and it being sold via the more artisan sales outlets, and not so much via the component ‘jobber’ outlets.

As part of one of the recent amplifier builds, I was looking for some Iskra half watt CF resistors to match with some I already have – I was staggered at the cost of them! I know they tend to have premium, but that much!

Terry
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Old 7th Feb 2023, 1:59 pm   #9
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Default Re: Top cap shortage?

For 807-type valves I have in the past used the finned springy-phosphor-bronze TO-5 clip-on heatsinks.

search "V4450 Heatsink" for examples.. Being bronze they are solderable-to.
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Old 7th Feb 2023, 2:53 pm   #10
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Default Re: Top cap shortage?

Make your own with casting, (not potting), resin. Make a mold in dental wax from your favourite design. Make the Connector from a coil of 1mm ø copper wire.
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Old 7th Feb 2023, 2:57 pm   #11
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Default Re: Top cap shortage?

There is a 'golden triangle' in Billingshurst, West Sussex. There is Langrex and Bilington's, but there is also at least one other there too, (I think they are linked to Watford Valves?). Interesting to know what the history is. Maybe there was a big depot there once for military storage and someone saw the future need?

I have visited Langrex and it is a real Aladdin's cave, well Aladdin's warehouse: just valves and valve related stuff.

Billington's could not have been more helpful shipping a box of stuff to Sweden, and I used to pick up a box of 100 CV4024 from Langrex each time I flew back from Gatwick, in lieu of a pension plan. At that time they had the remains of 100,000 that had been re-tested by Mullards in the early 80's from MoD supplies.

They are bound to be able to fix you up with something.
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Old 7th Feb 2023, 3:08 pm   #12
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Default Re: Top cap shortage?

I would have assumed that pure copper would be a poor choice for Top Caps.

It is not very 'springy' and after many heating and cooling cycles would tend to work loose.

A steel spring outside a copper or brass sheet contact would probable be OK.

A short piece of high temperature silicon tubing to hold the contact in place, might be OK on the cooler receiving valves
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Old 7th Feb 2023, 3:26 pm   #13
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Default Re: Top cap shortage?

Here's what I did years ago on an 807. It's just a small strip of ally bent and secured by the bolt and nut. Blimey, hadn't realised how grimey that old rig had got. 🙂

Aub
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Old 7th Feb 2023, 3:28 pm   #14
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Default Re: Top cap shortage?

Quote:
Originally Posted by Silicon View Post
I would have assumed that pure copper would be a poor choice for Top Caps.

It is not very 'springy' and after many heating and cooling cycles would tend to work loose.

A steel spring outside a copper or brass sheet contact would probable be OK.

A short piece of high temperature silicon tubing to hold the contact in place, might be OK on the cooler receiving valves
You would think so, as I did, but the idea seems perfectly fine if the coil is wound on a form a little smaller than needed for the cap so it grips. I have made the connectors from beryllium copper sheet/spring copper, though they don't seem to have any advantage, I have also seen the idea used with PL509's for PA stages in home brew transmitters, also without issue.

Regards, Greg.
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Old 7th Feb 2023, 3:37 pm   #15
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Default Re: Top cap shortage?

http://pmcomponentsnos.co.uk/epages/...5/Products/A10

I found these. I used to use PM Components back in the late nineties. Haven't dealt with them since. There are also 8 and 12 mm ones there too.

Aub
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Old 7th Feb 2023, 3:47 pm   #16
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Default Re: Top cap shortage?

I would have assumed that pure copper would be a poor choice for Top Caps.

It is not very 'springy' and after many heating and cooling cycles would tend to work loose.


I added a small 8BA nut and bolt to pinch up the connection and it was reliable.
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Old 7th Feb 2023, 4:30 pm   #17
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Default Re: Top cap shortage?

A while ago I restored an Ekco AC77 on which the top caps were flimsy and offensive to the eye (well to my eyes anyway), so they had to go. I made some new ones from 1.5mm brass sheet which only took a few minutes.

I've attached a rough sketch, and pics of an original one and a replacement I made.

To form the clip I rolled the brass around the shank of a 9mm drill bit, then adjusted it for a good fit on the top cap, but not so tight that it risked pulling off the cap. Brass 'work hardens' with bending and the clips were quite springy. The little tubular solder terminal I bent around a 2.5mm drill bit shank, then bent it down at right angles.

Only needs a vice, pair of tinsnips, a file and a junior hacksaw.

Ebay is awash with sellers of brass sheet of all thicknesses.

Typically a 200mm square sheet of 1.5mm thick sheet will cost a fiver post paid.

Just google:

'Brass sheet various sizes, various thickness. Models making, jewellery making' or:

'Brass Sheet plate guillotine Offcuts - 0.3mm to 3.0mm - Multiple Sizes'

Hope that's of interest.
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Old 7th Feb 2023, 4:40 pm   #18
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Default Re: Top cap shortage?

Quote:
Originally Posted by Aub View Post
http://pmcomponentsnos.co.uk/epages/...5/Products/A10

I found these. I used to use PM Components back in the late nineties. Havent dealt with them since. There are also 8 and 12 mm ones there too.

Aub
I've used PM components recently , for a bunch of 1.4V-filament valves [1S5/1T4/1R5 series] for my R209; they delivered the goods [still in 1945 US JAN packaging with little Navy anchors on them], so I'd have no issues doing business with them again.
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Old 8th Feb 2023, 8:29 am   #19
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Default Re: Top cap shortage?

Quote:
http://pmcomponentsnos.co.uk/epages/...5/Products/A10

I found these. I used to use PM Components back in the late nineties. Haven't dealt with them since. There are also 8 and 12 mm ones there too.
Yes, I also used PM, very good prices however I bought 10 10mm top caps from them some time ago, but they don't fit. They're 10mm just, but don't fit 3/8" top caps. They are not the smaller ones sent by mistake either, they're too big for an EF37A, hence my predicament.

Yes, the weird "valve triangle" around Billinghurst is odd and intrigueing, that aside Langrex show non in stock on their website. As they, Billinghurst et al get these from the same place, IE China everyone's in the same boat due to the extensive Covid lockdown's that were previously in place, hence the price increases & shortages.

If these were in an enclosed transmitter or amp with 500v HTI'd go DIY but as these will be going on an amp & I'll probably sell it at some point, I can't go the DIY route.

Thanks for all your IP, some cracking idea's there I'll log away for future use, Andy.
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