Source of cheap plastic/air variable tuning capacitors? - UK Vintage Radio Repair and Restoration Discussion Forum

MrBungle · 13th Sep 2016, 5:00 pm

I've just found my usual supply of cheap plastic variable capacitors has suddenly dried up and now the minimum order quantity is 10,000 instead of 1! https://www.rapidonline.com/trucap-a...tor-am-12-0255

The shocker for me is that they're around £4-5 a pop on ebay for a cheap polyvaricon and knackered old air variables (that I used to pay about 50p for at radio fairs!) are now going for £15-20!?!

Does anyone know another source of these or air variable capacitors that isn't extortionate?

Colin G8TMV · 13th Sep 2016, 5:09 pm

I've had the same problem, nowhere is as cheap as Rapid but I've found the following to be reasonable for small numbers:

https://www.esr.co.uk/

http://www.spectrumcomms.co.uk/

Colin

MrBungle · 13th Sep 2016, 5:53 pm

Excellent will try them. Thanks for the links.

13th Sep 2016, 5:56 pm

You can get 5 for less than a fiver from here on ebay http://www.ebay.co.uk/itm/5-Pcs-224p...4AAOSwCQNWeQ~k

MrBungle · 13th Sep 2016, 6:51 pm

Thanks for the link. I'm trying to avoid HK as the last three things I ordered took a month. I don't think my attention span is quite that long

davidw · 13th Sep 2016, 8:09 pm

Just a thought but have you asked Rapid..perhaps its just a typo!

Colin G8TMV · 13th Sep 2016, 8:21 pm

No, the number in stock has been dwindling for almost a year. Graham from the GQRP club bought the last of them for club projects.

I suspect the quoted MOQ is the smallest batch size the factory will consider making.

Colin

MrBungle · 13th Sep 2016, 10:16 pm

That explains that then

Will give the people at spectrum communications a call as they have some other bits that I'm interested in as well.

Karen O · 13th Sep 2016, 10:56 pm

Bowood sell them:

http://www.bowood-electronics.co.uk/...pacitor-p-1119

Diabolical Artificer · 14th Sep 2016, 8:08 am

I have a few PCB's with one or two on them if any good. Would old pocket radio's be a possible source for them?

Andy.

MrBungle · 14th Sep 2016, 8:49 am

Pocket radios was where I used to steal them from years ago. 5p each at jumble sales in the 1980s. Got copper wire, ferrites, IF cans, inevitably dodgy germanium transistors, audio transformers and speakers all for that money! I remember coming back having spent about 80p with two valve radio chassis, 5 pocket radios and a transformer that weighed about 3kg. The transformer was beyond my reverse engineering capability then and i proceeded to connect the mains to the 6.3v secondary which filled my nan's kitchen up with smoke in about 3 seconds flat.

Due to a gap in interest in the early 1990s I got rid of it all for some silly reason.

Back on topic there, I'm going to go for new ones this time as the older ones seem to be a little flaky. I'm not sure what dielectric they use but I've found it crumbles a bit after a few years. Probably why air variables command so much money!

I also spent some time last night designing a new air variable. I reckon it's not that difficult to produce your own as you can etch the vanes and cut acrylic ends out and assemble them onto threaded rods spaced with nuts/washers.

daviddeakin · 14th Sep 2016, 12:07 pm

Little 50pF ones are 35p from Bitsbox:
http://www.bitsbox.co.uk/index.php?m...t0dob4jfnponk2

bc312 · 14th Sep 2016, 12:11 pm

Also available from Spiratronics:
http://spiratronics.com/electronic-c...apacitors.html

MrBungle · 14th Sep 2016, 12:36 pm

Quote:

Originally Posted by daviddeakin

Little 50pF ones are 35p from Bitsbox

That's where I got my current stock.

Plus the eviscerated corpse of a fire damaged Tektronix 545.

Colin G8TMV · 14th Sep 2016, 1:30 pm

Quote:

Originally Posted by daviddeakin

Little 50pF ones are 35p from Bitsbox:
http://www.bitsbox.co.uk/index.php?m...t0dob4jfnponk2

Those are *trimmers* not variable caps

Colin

Variometer · 14th Sep 2016, 2:09 pm

This is one I made some time ago, but it would be more difficult to make a small one. This is 300pF, but it was purely guesswork

MrBungle · 14th Sep 2016, 3:12 pm

That's very nicely made. Very professional. How did you cut the vanes?

Variometer · 14th Sep 2016, 3:39 pm

The fixed ones were easy enough as they were oblong. I put all the aluminium for the moving vanes on top of each other and clamped them between two sheets of standard playwood with nuts & bolts in each corner. I stuck a paper template on the top piece of wood and drilled the spindle hole first and then cut the whole lot out together using a hobby bandsaw. The ends were black acrylic sheet. That was my first attempt. Acutally, I don't find it difficult to find commercially-made variable capacitors. There are still plenty of old sets available on car boot sales, often for two or three pounds. The spindle bushes were from old potentiometers.

MrBungle · 14th Sep 2016, 3:53 pm

Thanks for the info. Much appreciated.

Car boot sales around London seem to shift what I'd call a "stinker" radio for £20 these days! I'd come home with a car full for £2-3 a go.

Karen O · 14th Sep 2016, 4:10 pm

My experiments in television have been largely fuelled by a steady stream of cheap Chinese 5.5" TVs, usually bought for a couple of pounds.

These almost always have a radio PCB with said plastic film variable capacitors on them.

I've noticed a trend though: they used to be fixed to the board by two small screws while recent purchases have them fixed by soldered lugs. I find the latter harder to re-apply.

13th Sep 2016, 5:00 pm	#1
MrBungle Dekatron Join Date: Jun 2016 Location: London, UK. Posts: 3,687	Source of cheap plastic/air variable tuning capacitors? I've just found my usual supply of cheap plastic variable capacitors has suddenly dried up and now the minimum order quantity is 10,000 instead of 1! https://www.rapidonline.com/trucap-a...tor-am-12-0255 The shocker for me is that they're around £4-5 a pop on ebay for a cheap polyvaricon and knackered old air variables (that I used to pay about 50p for at radio fairs!) are now going for £15-20!?! Does anyone know another source of these or air variable capacitors that isn't extortionate?

13th Sep 2016, 5:09 pm	#2
Colin G8TMV Tetrode Join Date: Apr 2013 Location: Cambridge, Cambs. UK. Posts: 71	Re: Source of cheap plastic/air variable tuning capacitors? I've had the same problem, nowhere is as cheap as Rapid but I've found the following to be reasonable for small numbers: https://www.esr.co.uk/ http://www.spectrumcomms.co.uk/ Colin

13th Sep 2016, 5:53 pm	#3
MrBungle Dekatron Join Date: Jun 2016 Location: London, UK. Posts: 3,687	Re: Source of cheap plastic/air variable tuning capacitors? Excellent will try them. Thanks for the links.

13th Sep 2016, 5:56 pm	#4
Guest Guest Posts: n/a	Re: Source of cheap plastic/air variable tuning capacitors? You can get 5 for less than a fiver from here on ebay http://www.ebay.co.uk/itm/5-Pcs-224p...4AAOSwCQNWeQ~k

13th Sep 2016, 6:51 pm	#5
MrBungle Dekatron Join Date: Jun 2016 Location: London, UK. Posts: 3,687	Re: Source of cheap plastic/air variable tuning capacitors? Thanks for the link. I'm trying to avoid HK as the last three things I ordered took a month. I don't think my attention span is quite that long

13th Sep 2016, 8:09 pm	#6
davidw Heptode Join Date: Sep 2006 Location: Woodbridge, Suffolk, UK. Posts: 643	Re: Source of cheap plastic/air variable tuning capacitors? Just a thought but have you asked Rapid..perhaps its just a typo! __________________ Dave G1AGK. My perception is my reality!

13th Sep 2016, 8:21 pm	#7
Colin G8TMV Tetrode Join Date: Apr 2013 Location: Cambridge, Cambs. UK. Posts: 71	Re: Source of cheap plastic/air variable tuning capacitors? No, the number in stock has been dwindling for almost a year. Graham from the GQRP club bought the last of them for club projects. I suspect the quoted MOQ is the smallest batch size the factory will consider making. Colin

13th Sep 2016, 10:16 pm	#8
MrBungle Dekatron Join Date: Jun 2016 Location: London, UK. Posts: 3,687	Re: Source of cheap plastic/air variable tuning capacitors? That explains that then Will give the people at spectrum communications a call as they have some other bits that I'm interested in as well.

13th Sep 2016, 10:56 pm	#9
Karen O Rest in Peace Join Date: Jul 2011 Location: Bridgnorth, Shropshire, UK. Posts: 787	Re: Source of cheap plastic/air variable tuning capacitors? Bowood sell them: http://www.bowood-electronics.co.uk/...pacitor-p-1119

14th Sep 2016, 8:08 am	#10
Diabolical Artificer Dekatron Join Date: Jul 2009 Location: Sleaford, Lincs. UK. Posts: 7,667	Re: Source of cheap plastic/air variable tuning capacitors? I have a few PCB's with one or two on them if any good. Would old pocket radio's be a possible source for them? Andy. __________________ Curiosity hasn't killed this cat...so far.

14th Sep 2016, 8:49 am	#11
MrBungle Dekatron Join Date: Jun 2016 Location: London, UK. Posts: 3,687	Re: Source of cheap plastic/air variable tuning capacitors? Pocket radios was where I used to steal them from years ago. 5p each at jumble sales in the 1980s. Got copper wire, ferrites, IF cans, inevitably dodgy germanium transistors, audio transformers and speakers all for that money! I remember coming back having spent about 80p with two valve radio chassis, 5 pocket radios and a transformer that weighed about 3kg. The transformer was beyond my reverse engineering capability then and i proceeded to connect the mains to the 6.3v secondary which filled my nan's kitchen up with smoke in about 3 seconds flat. Due to a gap in interest in the early 1990s I got rid of it all for some silly reason. Back on topic there, I'm going to go for new ones this time as the older ones seem to be a little flaky. I'm not sure what dielectric they use but I've found it crumbles a bit after a few years. Probably why air variables command so much money! I also spent some time last night designing a new air variable. I reckon it's not that difficult to produce your own as you can etch the vanes and cut acrylic ends out and assemble them onto threaded rods spaced with nuts/washers.

14th Sep 2016, 12:07 pm	#12
daviddeakin Hexode Join Date: Apr 2007 Location: W Yorks, UK. Posts: 407	Re: Source of cheap plastic/air variable tuning capacitors? Little 50pF ones are 35p from Bitsbox: http://www.bitsbox.co.uk/index.php?m...t0dob4jfnponk2

14th Sep 2016, 12:11 pm	#13
bc312 Pentode Join Date: Feb 2005 Location: Longfield, Kent, UK. Posts: 240	Re: Source of cheap plastic/air variable tuning capacitors? Also available from Spiratronics: http://spiratronics.com/electronic-c...apacitors.html __________________ Leave me alone - I know what I'm doing. BVWS member, EUG, G-QRP Radio Bygones/Radiophile

14th Sep 2016, 2:09 pm	#16
Variometer Retired Dormant Member Join Date: May 2008 Location: Preston, Lancashire, UK. Posts: 428	Re: Source of cheap plastic/air variable tuning capacitors? This is one I made some time ago, but it would be more difficult to make a small one. This is 300pF, but it was purely guesswork Attached Thumbnails

14th Sep 2016, 3:12 pm	#17
MrBungle Dekatron Join Date: Jun 2016 Location: London, UK. Posts: 3,687	Re: Source of cheap plastic/air variable tuning capacitors? That's very nicely made. Very professional. How did you cut the vanes?

14th Sep 2016, 3:39 pm	#18
Variometer Retired Dormant Member Join Date: May 2008 Location: Preston, Lancashire, UK. Posts: 428	Re: Source of cheap plastic/air variable tuning capacitors? The fixed ones were easy enough as they were oblong. I put all the aluminium for the moving vanes on top of each other and clamped them between two sheets of standard playwood with nuts & bolts in each corner. I stuck a paper template on the top piece of wood and drilled the spindle hole first and then cut the whole lot out together using a hobby bandsaw. The ends were black acrylic sheet. That was my first attempt. Acutally, I don't find it difficult to find commercially-made variable capacitors. There are still plenty of old sets available on car boot sales, often for two or three pounds. The spindle bushes were from old potentiometers.

14th Sep 2016, 3:53 pm	#19
MrBungle Dekatron Join Date: Jun 2016 Location: London, UK. Posts: 3,687	Re: Source of cheap plastic/air variable tuning capacitors? Thanks for the info. Much appreciated. Car boot sales around London seem to shift what I'd call a "stinker" radio for £20 these days! I'd come home with a car full for £2-3 a go.

14th Sep 2016, 4:10 pm	#20
Karen O Rest in Peace Join Date: Jul 2011 Location: Bridgnorth, Shropshire, UK. Posts: 787	Re: Source of cheap plastic/air variable tuning capacitors? My experiments in television have been largely fuelled by a steady stream of cheap Chinese 5.5" TVs, usually bought for a couple of pounds. These almost always have a radio PCB with said plastic film variable capacitors on them. I've noticed a trend though: they used to be fixed to the board by two small screws while recent purchases have them fixed by soldered lugs. I find the latter harder to re-apply.