Output transformer for Vidor CN429 (any battery portable really) - UK Vintage Radio Repair and Restoration Discussion Forum

coopzone · 6th May 2018, 7:05 pm

Has anyone got a cheap output transformer for a battery mw/lw radio, this one is a vidor "Lady Margaret" but I am pretty sure any transformer for a DL96 valve will do it.

I can pay postage etc and a reasonable amount for the transformer.

Derek

p.s. Currently working on a 240V/6V transformer for testing. It's not to far of the original - surprisingly.

Techman · 6th May 2018, 7:30 pm

I've also got one of these small Vidor radios in need of an output transformer - me and a hundred other forum members I suspect. These nearly always have o/c output transformers due to having batteries left in them and the venting of corrosive gasses in a confined and un-ventilated space rotting the primary windings. These have the same rareness as a non broken speed change knob for the early BSR record changer and the Bush badge from their well known record player - people are always asking for them and none are spare because there's more broken and missing than there are scrap units to rob. So I think you'll be joining the end of a very long queue. However, I understand that RS does a near enough replacement fairly cheap and also there's the two forum transformer and coil re-winders, Ed Dinning and Mike Barker.

Myself, I'm hoping to find a suitable transformer amoungst my ancient stash, or failing that, I'll do as you're doing at the moment with a small mains transformer.

Good luck with it.

paulsherwin · 6th May 2018, 7:47 pm

Just a reminder that the turns ratio isn't critical and any transformer from a scrap set is likely to work acceptably well, even if from a mains set. The difficulty is physically fitting them into the available space.

coopzone · 7th May 2018, 9:05 am

Ok I think I get the picture! We are talking "Sun on a bank holiday", "Hens teeth" etc. So I have constructed a small metal bracket (from an old biscuit tin lid!) and fitted the 240v/6v mains transformer in the same location the original was in. It works ok, probably put the hi-fi enthusiasts teach on edge - but this is an old AM radio so 20-20khz is never going to happen!

I think maybe the ops could move this to the "Domestic radio" forum to help others, thanks.

Derek

Leon Crampin · 7th May 2018, 10:04 am

A small mains transformer (say 3 VA) chosen to give the right ratio will do for a battery portable. The standing DC in the primary is generally insufficient to saturate the core.

Leon.

coopzone · 7th May 2018, 3:20 pm

Pictures of fitted transformer, working ok. Still a way to go to finish the restore, but currently enjoying the garden listening to it.

Argus25 · 8th May 2018, 1:36 am

I would like to alert members to a "darling" of a baby output transformer suited to battery valve radios, its 45 x 35 x 40 mm and is enclosed in metal covers which gives it a vintage look.

So firstly, it has a suitable size for these radios and a good vintage look to it. It was in fact originally designed by Fender for a reverb unit, but it makes for a wonderful single ended low power audio output transformer.

Secondly, its impedance is 14.5k to 4R. which is suited to the relatively high plate resistances of small battery valve audio output valves. I have used these in vintage battery sets and they are also fine with an 8R speaker.

This transformer is available from Wes Components:

https://www.wes.com.au/mediapub/eboo...p/1383/#zoom=z

PART CODE NSC022921 called a "Fender Coupling Transformer"

I don't think it is air gapped (butt stacked) but as noted with the low anode currents in these radios, it doesn't matter.

Cobaltblue · 8th May 2018, 8:36 am

Seems you have to register to get a price so how much is it?

Cheers

Mike T

ionburn · 8th May 2018, 10:52 am

I used the one supplied by RS components. It needs minute attention to fit in a Lady Margaret, but works well. Just to remember to change the coupling capacitor to the output stage as, if this is faulty, it may have caused the problem.

Argus25 · 8th May 2018, 11:26 am

Quote:

Originally Posted by Cobaltblue

Seems you have to register to get a price so how much is it?

I don't have the WES price list on hand, but I'm pretty sure this is the same one at AES for $15:

https://www.tubesandmore.com/product...t-3-12-w-8-ohm

so not a dear part.

6th May 2018, 7:05 pm	#1
coopzone Hexode Join Date: Jan 2018 Location: Cannock, Staffordshire, UK. Posts: 268	Output transformer for Vidor CN429 (any battery portable really) Has anyone got a cheap output transformer for a battery mw/lw radio, this one is a vidor "Lady Margaret" but I am pretty sure any transformer for a DL96 valve will do it. I can pay postage etc and a reasonable amount for the transformer. Derek p.s. Currently working on a 240V/6V transformer for testing. It's not to far of the original - surprisingly.

6th May 2018, 7:30 pm	#2
Techman Dekatron Join Date: Nov 2009 Location: Lincolnshire, UK. Posts: 5,000	Re: Output transformer for Vidor CN429 (any battery portable really) I've also got one of these small Vidor radios in need of an output transformer - me and a hundred other forum members I suspect. These nearly always have o/c output transformers due to having batteries left in them and the venting of corrosive gasses in a confined and un-ventilated space rotting the primary windings. These have the same rareness as a non broken speed change knob for the early BSR record changer and the Bush badge from their well known record player - people are always asking for them and none are spare because there's more broken and missing than there are scrap units to rob. So I think you'll be joining the end of a very long queue. However, I understand that RS does a near enough replacement fairly cheap and also there's the two forum transformer and coil re-winders, Ed Dinning and Mike Barker. Myself, I'm hoping to find a suitable transformer amoungst my ancient stash, or failing that, I'll do as you're doing at the moment with a small mains transformer. Good luck with it.

6th May 2018, 7:47 pm	#3
paulsherwin Moderator Join Date: Jun 2003 Location: Oxford, UK Posts: 27,969	Re: Output transformer for Vidor CN429 (any battery portable really) Just a reminder that the turns ratio isn't critical and any transformer from a scrap set is likely to work acceptably well, even if from a mains set. The difficulty is physically fitting them into the available space.

7th May 2018, 9:05 am	#4
coopzone Hexode Join Date: Jan 2018 Location: Cannock, Staffordshire, UK. Posts: 268	Re: Output transformer for Vidor CN429 (any battery portable really) Ok I think I get the picture! We are talking "Sun on a bank holiday", "Hens teeth" etc. So I have constructed a small metal bracket (from an old biscuit tin lid!) and fitted the 240v/6v mains transformer in the same location the original was in. It works ok, probably put the hi-fi enthusiasts teach on edge - but this is an old AM radio so 20-20khz is never going to happen! I think maybe the ops could move this to the "Domestic radio" forum to help others, thanks. Derek

7th May 2018, 10:04 am	#5
Leon Crampin Octode Join Date: Nov 2005 Location: Surrey, UK. Posts: 1,874	Re: Output transformer for Vidor CN429 (any battery portable really) A small mains transformer (say 3 VA) chosen to give the right ratio will do for a battery portable. The standing DC in the primary is generally insufficient to saturate the core. Leon.

7th May 2018, 3:20 pm	#6
coopzone Hexode Join Date: Jan 2018 Location: Cannock, Staffordshire, UK. Posts: 268	Re: Output transformer for Vidor CN429 (any battery portable really) Pictures of fitted transformer, working ok. Still a way to go to finish the restore, but currently enjoying the garden listening to it. Attached Thumbnails

8th May 2018, 1:36 am	#7
Argus25 No Longer a Member Join Date: Oct 2016 Location: Maroochydore, Queensland, Australia. Posts: 2,679	Re: Output transformer for Vidor CN429 (any battery portable really) I would like to alert members to a "darling" of a baby output transformer suited to battery valve radios, its 45 x 35 x 40 mm and is enclosed in metal covers which gives it a vintage look. So firstly, it has a suitable size for these radios and a good vintage look to it. It was in fact originally designed by Fender for a reverb unit, but it makes for a wonderful single ended low power audio output transformer. Secondly, its impedance is 14.5k to 4R. which is suited to the relatively high plate resistances of small battery valve audio output valves. I have used these in vintage battery sets and they are also fine with an 8R speaker. This transformer is available from Wes Components: https://www.wes.com.au/mediapub/eboo...p/1383/#zoom=z PART CODE NSC022921 called a "Fender Coupling Transformer" I don't think it is air gapped (butt stacked) but as noted with the low anode currents in these radios, it doesn't matter.

8th May 2018, 8:36 am	#8
Cobaltblue Moderator Join Date: Dec 2010 Location: Exeter, Devon and Poole, Dorset UK. Posts: 6,878	Re: Output transformer for Vidor CN429 (any battery portable really) Seems you have to register to get a price so how much is it? Cheers Mike T __________________ Invisible airwaves crackle with life or at least they used to Mike T BVWS member. www.cossor.co.uk

8th May 2018, 10:52 am	#9
ionburn Heptode Join Date: Dec 2014 Location: Lincoln, Lincolnshire, UK. Posts: 583	Re: Output transformer for Vidor CN429 (any battery portable really) I used the one supplied by RS components. It needs minute attention to fit in a Lady Margaret, but works well. Just to remember to change the coupling capacitor to the output stage as, if this is faulty, it may have caused the problem.