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 > General Vintage Technology > General Vintage Technology Discussions

Notices

General Vintage Technology Discussions For general discussions about vintage radio and other vintage electronics etc.

Reply
 
Thread Tools
Old 11th May 2022, 10:19 pm   #1
AdrianH
Octode
 
AdrianH's Avatar
 
Join Date: Mar 2020
Location: Blackburn with Darwen, Lancashire, UK.
Posts: 1,137
Default Transformer or choke and RC unit

These are starting to intrigue me, in a bits box is an old transformer of unknown make and a Bullphone radio products RC unit.

The transformer has no label on the top as it is missing, but the three terminals from left to right are :-

HT+, C , P&C1. The terminal on the side is labelled Earth.
Click image for larger version

Name:	xfmr1.jpg
Views:	107
Size:	41.4 KB
ID:	257006

Typically around 400 Ohms between HT+ and C and C and P&C1 so 800 Ohms in total, In inductance approx 3.7H per section, but 18H total across HT+ and P&C1. No resistance to Earth, guess it could connect to the laminations or it is open circuit.

Click image for larger version

Name:	rc1.jpg
Views:	88
Size:	51.9 KB
ID:	257007
The next unit is basically a holder for glass style resistors, grid leak and I am guessing Plate load resistor. Terminals are HT, P, G and GB, guessing grid bias battery? The caps in the unit are not very well when being read with my TC1 so I assume very leaky. Perhaps I should warm the unit up to remove the wax and see what is in there.

I have several caps in Bakelite cases and guess they will all be duff by now all in wax so should be reasonably easy to replace. I have a couple of 4 pin valve holders and valves etc so thinking of adding a 1920/1930's early battery style project to my list of to do's.

If anyone knows details of the two objects I would appreciate the information.

Adrian
__________________
Asking questions and learning, or trying to!
Youtube EF91Valve
AdrianH is online now   Reply With Quote
Old 12th May 2022, 12:22 am   #2
radiograham
Hexode
 
Join Date: Oct 2017
Location: Manchester, UK.
Posts: 281
Default Re: Transformer or choke and RC unit

Quote:
Originally Posted by AdrianH View Post
These are starting to intrigue me, in a bits box is an old transformer of unknown make and a Bullphone radio products RC unit.

The transformer has no label on the top as it is missing, but the three terminals from left to right are :-

HT+, C , P&C1. The terminal on the side is labelled Earth.
Attachment 257006

Typically around 400 Ohms between HT+ and C and C and P&C1 so 800 Ohms in total, In inductance approx 3.7H per section, but 18H total across HT+ and P&C1. No resistance to Earth, guess it could connect to the laminations or it is open circuit.

Attachment 257007
The next unit is basically a holder for glass style resistors, grid leak and I am guessing Plate load resistor. Terminals are HT, P, G and GB, guessing grid bias battery? The caps in the unit are not very well when being read with my TC1 so I assume very leaky. Perhaps I should warm the unit up to remove the wax and see what is in there.

I have several caps in Bakelite cases and guess they will all be duff by now all in wax so should be reasonably easy to replace. I have a couple of 4 pin valve holders and valves etc so thinking of adding a 1920/1930's early battery style project to my list of to do's.

If anyone knows details of the two objects I would appreciate the information.

Adrian
Hi Adrian,i am pretty sure the first is a Telsen tapped output choke.If you google Telsen mag they are all on american radio history website.Dont recognise the second unit i'm afraid. Graham.

Last edited by radiograham; 12th May 2022 at 12:27 am. Reason: atachment
radiograham is offline   Reply With Quote
Old 12th May 2022, 12:32 am   #3
radiograham
Hexode
 
Join Date: Oct 2017
Location: Manchester, UK.
Posts: 281
Default Re: Transformer or choke and RC unit

Telsen Mag.
Attached Files
File Type: pdf Telsen_Radiomag_No.1.pdf (3.95 MB, 68 views)
radiograham is offline   Reply With Quote
Old 12th May 2022, 6:40 am   #4
AdrianH
Octode
 
AdrianH's Avatar
 
Join Date: Mar 2020
Location: Blackburn with Darwen, Lancashire, UK.
Posts: 1,137
Default Re: Transformer or choke and RC unit

Thank you Graham, I will have a good look through that mag.

Adrian
__________________
Asking questions and learning, or trying to!
Youtube EF91Valve
AdrianH is online now   Reply With Quote
Old 12th May 2022, 7:22 am   #5
John M0GLN
Octode
 
John M0GLN's Avatar
 
Join Date: Jan 2004
Location: Southport, Lancashire, UK.
Posts: 1,109
Default Re: Transformer or choke and RC unit

Other than posting this scan from a 1930-31 catalogue showing something similar, I can't offer any other info' about them.

John
Attached Thumbnails
Click image for larger version

Name:	rcd unit.jpg
Views:	44
Size:	55.7 KB
ID:	257015  
John M0GLN is offline   Reply With Quote
Old 12th May 2022, 10:34 am   #6
AdrianH
Octode
 
AdrianH's Avatar
 
Join Date: Mar 2020
Location: Blackburn with Darwen, Lancashire, UK.
Posts: 1,137
Default Re: Transformer or choke and RC unit

Thanks John

I have just taken the R.C Unit to pieces, well melted out the bitumen, was really hoping it was a hard wax. Found where the cap was connected.

Click image for larger version

Name:	RC.jpg
Views:	15
Size:	34.8 KB
ID:	257028

Looking through the magazine from Graham, I guess it makes building a radio a bit like a Meccano build, bolt things down and wire between the connections.

I have downloaded all six of the Telsen Magazines and will print off and have a good read.

Adrian
__________________
Asking questions and learning, or trying to!
Youtube EF91Valve
AdrianH is online now   Reply With Quote
Old 12th May 2022, 11:17 am   #7
PJL
Dekatron
 
Join Date: Sep 2005
Location: Seaford, East Sussex, UK.
Posts: 5,601
Default Re: Transformer or choke and RC unit

The RC coupler was a low cost alternative to an audio intervalve transformer. You will find similar markings for P (plate/anode), HT, G (grid), GB (grid bias battery) on the transformers. The disadvantage with the RC coupling is lower load impedance and loss of gain from the transformer turns ratio.
PJL is offline   Reply With Quote
Old 12th May 2022, 11:18 am   #8
The Philpott
Dekatron
 
The Philpott's Avatar
 
Join Date: Aug 2016
Location: Colchester, Essex, UK.
Posts: 3,475
Default Re: Transformer or choke and RC unit

It may have been high grade 'stockholm tar', ie derived from wood not crude.
Dave
The Philpott is online now   Reply With Quote
Old 12th May 2022, 11:35 am   #9
AdrianH
Octode
 
AdrianH's Avatar
 
Join Date: Mar 2020
Location: Blackburn with Darwen, Lancashire, UK.
Posts: 1,137
Default Re: Transformer or choke and RC unit

Quote:
Originally Posted by PJL View Post
The RC coupler was a low cost alternative to an audio intervalve transformer. You will find similar markings for P (plate/anode), HT, G (grid), GB (grid bias battery) on the transformers. The disadvantage with the RC coupling is lower load impedance and loss of gain from the transformer turns ratio.
Now that makes a lot more sense to me, I was initially thinking of being for just one valve, but as the coupling between two valves makes it much more understandable

Quote:
Originally Posted by The Philpott View Post
It may have been high grade 'stockholm tar', ie derived from wood not crude.
Dave
OK what ever it is I still wish it was a wax, although I can understand the wax melting within a radio set. I may soak in acetone to remove the remnants of the 'tar', not sure what it will do to the Bakelite.

I have approx 9, 4 pin valves, a couple of holders, some other chokes and variable caps, even what looks like a NOS Cossor 2P output valve, should be able to come up with something as a project.

Adrian
__________________
Asking questions and learning, or trying to!
Youtube EF91Valve
AdrianH is online now   Reply With Quote
Old 12th May 2022, 12:07 pm   #10
Refugee
Dekatron
 
Refugee's Avatar
 
Join Date: Apr 2012
Location: Worksop, Nottinghamshire, UK.
Posts: 5,491
Default Re: Transformer or choke and RC unit

Stockholm tar has a very strong smell of kippers even if it is just a little smudge around the tin lid.
I know because I have seen and smelt it used in a non electronic setting.
Refugee is offline   Reply With Quote
Old 12th May 2022, 12:52 pm   #11
AdrianH
Octode
 
AdrianH's Avatar
 
Join Date: Mar 2020
Location: Blackburn with Darwen, Lancashire, UK.
Posts: 1,137
Default Re: Transformer or choke and RC unit

Then I think it is bitumen, no particular smell to it.

Acetone not working well may try turps.

Adrian
__________________
Asking questions and learning, or trying to!
Youtube EF91Valve
AdrianH is online now   Reply With Quote
Old 12th May 2022, 4:50 pm   #12
The Philpott
Dekatron
 
The Philpott's Avatar
 
Join Date: Aug 2016
Location: Colchester, Essex, UK.
Posts: 3,475
Default Re: Transformer or choke and RC unit

Or wd40. It's bakelite-friendly.
The Philpott is online now   Reply With Quote
Old 12th May 2022, 10:29 pm   #13
radiograham
Hexode
 
Join Date: Oct 2017
Location: Manchester, UK.
Posts: 281
Default Re: Transformer or choke and RC unit

Hi,the imposing looking building on the front of the telsen mags is still there or it was in early 90s.Not as impressive as on the mags,artistic licence much in evidence.Took me a while to find it nestling under a flyover in aston birmingham.
radiograham is offline   Reply With Quote
Old 13th May 2022, 9:00 am   #14
AdrianH
Octode
 
AdrianH's Avatar
 
Join Date: Mar 2020
Location: Blackburn with Darwen, Lancashire, UK.
Posts: 1,137
Default Re: Transformer or choke and RC unit

Oh I don't know the building looks OK to me, courtesy of google street maps.

Click image for larger version

Name:	Telsen.jpg
Views:	55
Size:	72.1 KB
ID:	257074

I have been checking out so caps or condensers to give them the term of the time.

Click image for larger version

Name:	caps.jpg
Views:	37
Size:	77.2 KB
ID:	257075
All basically short circuit, the best i have managed to recover is a 2 mF but at 180 Volts it has 400uA leakage. So at some point I will melt out the bitumen on them and fit modern internals and then try to reseal.

I have some smaller mica caps that may test OK.
A long term idea for a project I think. time to get on with some smaller projects and get them out of the way.

Adrian
__________________
Asking questions and learning, or trying to!
Youtube EF91Valve
AdrianH is online now   Reply With Quote
Old 13th May 2022, 12:05 pm   #15
PJL
Dekatron
 
Join Date: Sep 2005
Location: Seaford, East Sussex, UK.
Posts: 5,601
Default Re: Transformer or choke and RC unit

The less messy way to remove bitumen is to freeze it then chip it out, just beware that the bitumen chips don't end up on the carpet as when thawed they stick like tar.
PJL is offline   Reply With Quote
Old 13th May 2022, 6:29 pm   #16
Ed_Dinning
Dekatron
 
Join Date: Jan 2004
Location: Newcastle upon Tyne, Tyne & Wear, UK.
Posts: 7,532
Default Re: Transformer or choke and RC unit

Hi Adrian, plenty of designs in the Radiomags to use the parts on, but you will need to build your own baseboard and source some material for the front panel

Ed
Ed_Dinning is online now   Reply With Quote
Old 13th May 2022, 6:32 pm   #17
AdrianH
Octode
 
AdrianH's Avatar
 
Join Date: Mar 2020
Location: Blackburn with Darwen, Lancashire, UK.
Posts: 1,137
Default Re: Transformer or choke and RC unit

Thanks PJL and Ed.

Yes there are lots out there, I could do with some interstage transformers but have time to try and find some, it is not an urgent project idea.

Adrian
__________________
Asking questions and learning, or trying to!
Youtube EF91Valve
AdrianH is online now   Reply With Quote
Old 13th May 2022, 6:34 pm   #18
AdrianH
Octode
 
AdrianH's Avatar
 
Join Date: Mar 2020
Location: Blackburn with Darwen, Lancashire, UK.
Posts: 1,137
Default Re: Transformer or choke and RC unit

Forgot to add looking through the Telsen magazines, the loudspeaker must have been in the hundreds if not K Ohms range?

Adrian
__________________
Asking questions and learning, or trying to!
Youtube EF91Valve
AdrianH is online now   Reply With Quote
Old 14th May 2022, 2:28 am   #19
radiograham
Hexode
 
Join Date: Oct 2017
Location: Manchester, UK.
Posts: 281
Default Re: Transformer or choke and RC unit

Quote:
Originally Posted by AdrianH View Post
Oh I don't know the building looks OK to me, courtesy of google street maps.

Attachment 257074

I have been checking out so caps or condensers to give them the term of the time.

Attachment 257075
All basically short circuit, the best i have managed to recover is a 2 mF but at 180 Volts it has 400uA leakage. So at some point I will melt out the bitumen on them and fit modern internals and then try to reseal.

I have some smaller mica caps that may test OK.
A long term idea for a project I think. time to get on with some smaller projects and get them out of the way.

Adrian
That look's better than i remember,glad to see it is still there. Graham.
radiograham is offline   Reply With Quote
Old 14th May 2022, 6:54 am   #20
AdrianH
Octode
 
AdrianH's Avatar
 
Join Date: Mar 2020
Location: Blackburn with Darwen, Lancashire, UK.
Posts: 1,137
Default Re: Transformer or choke and RC unit

Graham as an aside, I found another Matsui remote, pm me your address and I will get it to you.

Adrian
__________________
Asking questions and learning, or trying to!
Youtube EF91Valve
AdrianH is online now   Reply With Quote
Reply

Thread Tools



All times are GMT. The time now is 8:08 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 - 2022, vBulletin Solutions, Inc.
Copyright ©2002 - 2021, Paul Stenning.