UK Vintage Radio Repair and Restoration Powered By Google Custom Search Vintage Radio and TV Service Data

Go Back   UK Vintage Radio Repair and Restoration Discussion Forum > Specific Vintage Equipment > Vintage Radio (domestic)

Notices

Vintage Radio (domestic) Domestic vintage radio (wireless) receivers only.

Closed Thread
 
Thread Tools
Old 12th Nov 2018, 8:40 pm   #21
Electronpusher0
Nonode
 
Join Date: Jun 2016
Location: Bognor Regis, West Sussex, UK.
Posts: 2,288
Default Re: KN Products 1930s Radio - Car Boot find

I have just managed to pick up a NOS 2 V accumulator on ebay. It was not advertised as NOS but it is still sealed and never been filled.
I have a local car repairers that can fill it when I am ready.

Peter
Attached Thumbnails
Click image for larger version

Name:	IMG_1505.jpg
Views:	92
Size:	67.0 KB
ID:	172722   Click image for larger version

Name:	IMG_1506.jpg
Views:	85
Size:	56.9 KB
ID:	172723   Click image for larger version

Name:	IMG_1507.jpg
Views:	81
Size:	81.0 KB
ID:	172724   Click image for larger version

Name:	IMG_1509.jpg
Views:	72
Size:	55.5 KB
ID:	172725  
Electronpusher0 is offline  
Old 12th Nov 2018, 8:58 pm   #22
G6Tanuki
Dekatron
 
G6Tanuki's Avatar
 
Join Date: Apr 2012
Location: Wiltshire, UK.
Posts: 13,953
Default Re: KN Products 1930s Radio - Car Boot find

Lovely! I hope that after all these years of idleness it comes back to life.

[I remember in the 1970s buying a bunch of ex-military-surplus 2V 16AH accumulators that were originally specced for a WWII-era "Wireless Set 17" vibrator-supply. They were made by "Pritchett & Gold and Electric Power Storage". I sourced some appropriate H2SO4 and expected them to take a charge, but time had taken its toll and they very quickly shed the spongy-lead paste from their plates, rendering them useless].
G6Tanuki is offline  
Old 16th Nov 2018, 8:35 pm   #23
Electronpusher0
Nonode
 
Join Date: Jun 2016
Location: Bognor Regis, West Sussex, UK.
Posts: 2,288
Default Re: KN Products 1930s Radio - Car Boot find

I was going to put this set aside but cannot resist starting the restoration.

I took the electronics out of the case so the case can be restored (it is on a wooden sub chassis.

The good news is that the loudspeaker seems intact and reads 50 ohms at dc.

The bad news is that both interstage transformers have open circuit windings. The primary on one and the secondary on the other.

They are both identical, made by Keston Radio Coil Company.

At dc the primary resistance is 933 ohm and the secondary is 5K ohm.

Can these be re-wound and how difficult would it be?

The other thing is that there is a distinct musty smell from the inside, partially from the wood and partially from the mould on the cotton covered wire of the loop aerial (see photos). Is this worth trying to fix or should I simply rewind the aerial with new wire ( I have a large reel of cotton covered wire.)?

Finally there is very puzzling mod someone has added. Someone has mounted a small lens ended bulb in series with the common 0v wire.

Any thoughts would be appreciated.

Peter
Attached Thumbnails
Click image for larger version

Name:	IMG_1519 (Large).jpg
Views:	75
Size:	56.4 KB
ID:	172926   Click image for larger version

Name:	IMG_1518 (Large).jpg
Views:	74
Size:	92.0 KB
ID:	172927   Click image for larger version

Name:	IMG_1514 (Large).jpg
Views:	69
Size:	48.2 KB
ID:	172928   Click image for larger version

Name:	IMG_1513 (Large).jpg
Views:	68
Size:	68.3 KB
ID:	172929   Click image for larger version

Name:	IMG_1511 (Large).jpg
Views:	72
Size:	57.5 KB
ID:	172930  

Electronpusher0 is offline  
Old 16th Nov 2018, 9:39 pm   #24
G6Tanuki
Dekatron
 
G6Tanuki's Avatar
 
Join Date: Apr 2012
Location: Wiltshire, UK.
Posts: 13,953
Default Re: KN Products 1930s Radio - Car Boot find

The transformers could be rewound, yes - but that would not be cheap. I'd be more inclined to kludge together something using small mains-transformers. In the past I've used little "wall-wart" transformers with two 115V windings - the primary windings are normally wired in series for 230V use but you can use the 'centre-tap' as a sort-of autotransformer and use a capacitor to feed the next stage.
G6Tanuki is offline  
Old 16th Nov 2018, 9:41 pm   #25
Ed_Dinning
Dekatron
 
Join Date: Jan 2004
Location: Newcastle upon Tyne, Tyne & Wear, UK.
Posts: 8,173
Default Re: KN Products 1930s Radio - Car Boot find

Hi Peter, small bulb is designed to act as a fuse if the HT gets connected to the filaments, common on sets like this.

The mould can probably be brushed of the CC wire and a coat of clear lacquer applied if necessary.

If the transformer can be stripped it may be possible to swap pri and sec to get one good transformer.
The transformers look as if they are fitted with cheeks so should be easy to rewind with very fine wire (say 0.05mm), but you will find all the details when you strip it.
Not a difficult process but time consuming and easier if you have even a hand winding machine. Note that it is not necessary to use layers of paper between layers of wire with modern grade 2 enamelled wire. This paper is probably the cause of your problems as it is hygroscopic.

These sets normally perform well when restored.

Ed
Ed_Dinning is offline  
Old 17th Nov 2018, 10:22 pm   #26
Electronpusher0
Nonode
 
Join Date: Jun 2016
Location: Bognor Regis, West Sussex, UK.
Posts: 2,288
Default Re: KN Products 1930s Radio - Car Boot find

Thanks Ed,
I have ordered a small hand winder and will have a go at rewinding the transformers.
one of the anode inductors was also open circuit but fortunately it was the end termination that was open. I managed to resolder it.

Peter
Electronpusher0 is offline  
Old 19th Nov 2018, 6:00 pm   #27
Electronpusher0
Nonode
 
Join Date: Jun 2016
Location: Bognor Regis, West Sussex, UK.
Posts: 2,288
Default Re: KN Products 1930s Radio - Car Boot find

I have stripped the laminations from one of the transformers, they are somewhat rusty but can be cleaned up. They originally had very thin paper between each but this has broken up. I propose lacquering them afer cleaning to get some insulation back befor reassembly, assuming the rewind is successful.

I still have to source the valves. I have managed to get a PM2A that tests good but need 4 off PM1HF (I think, based on what is used in similar sets)
I can get PM1HL, are these reasonably equivalent? I have checked the data sheets, the PM1HL is higher gain but I do not know if they can be used in this application.

Peter
Electronpusher0 is offline  
Old 1st Dec 2018, 12:20 pm   #28
Electronpusher0
Nonode
 
Join Date: Jun 2016
Location: Bognor Regis, West Sussex, UK.
Posts: 2,288
Default Re: KN Products 1930s Radio - Car Boot find

Quick update.
I have now got all the valves.
Have designed a mains power supply as an alternative to batteries (I still intend making some batteries but this is to get it running.

I am rewinding the transformers - 14,000 turns on the secondary!

I have traced the schematic and attach it for reference.

Peter
Attached Files
File Type: pdf KN Schematic.pdf (41.1 KB, 52 views)
Electronpusher0 is offline  
Closed Thread

Thread Tools



All times are GMT +1. The time now is 3:45 pm.


All information and advice on this forum is subject to the WARNING AND DISCLAIMER located at https://www.vintage-radio.net/rules.html.
Failure to heed this warning may result in death or serious injury to yourself and/or others.


Powered by vBulletin®
Copyright ©2000 - 2024, vBulletin Solutions, Inc.
Copyright ©2002 - 2023, Paul Stenning.