Coil Inductance No 14 - UK Vintage Radio Repair and Restoration Discussion Forum

BigClick · 21st Mar 2016, 5:22 pm

Hi telephony folks,

I am thinking about making a coil to convert a Bellset 1a to a Bellset1.

I have some information that might help work out the guage of wire from the turns and resistance...

... two windings of 26 Ohms (1400 turns) (tags 3 & 4) and 17 Ohms (1700 turns) (tags 1 & 2).

The problem would be the core.

So does anyone have a coil no14 they could measure for me?

Even better, does anyone have a spare coil no 14 to sell?

Kind regards,
Ray

PJL · 21st Mar 2016, 10:27 pm

Read this thread, https://www.vintage-radio.net/forum/...=119966&page=2

I came to the same conclusion about the problems in obtaining the right core material.

I put a circuit at the end based on using a much more readily available 700 series induction coil and the turns ratio is close enough.

PS: I have a feeling there was an error in my circuit and the line connections 5/2 should be reversed.

BigClick · 21st Mar 2016, 11:12 pm

Hi PJL and thanks,
Yes I came across a very old marketing blurb for the bellset inductance coil (GEC) and they go on about how the core is made from finest Swedish steal that is cold rolled to align the crystals and is then annealed etc etc.

So did you body snatch from a 700 series?

In the meantime I have seen this site; http://oldphoneguy.net
in one of his "booklets" he describes a homebrew ASTIC circuit using a miniature transformer available from Farnell for under a fiver; TRIAD MAGNETICS TY-145P

It looks quite neat and its suitable for receivers with an impedance ranging from 75 - 300 ohms

I have got a couple of bellset 1a and a couple of bellset 26s so it might be worth setting one of them up up and trying it out.

PJL · 22nd Mar 2016, 2:07 pm

I found the 700 induction coil on ebay. Having said that it cost me the same as a complete phone I saw for £6 at an antique market.

BigClick · 23rd Mar 2016, 9:47 am

Quote:

Originally Posted by PJL

I found the 700 induction coil on ebay. Having said that it cost me the same as a complete phone I saw for £6 at an antique market.

I have seen your circuit for using a 700 series coil. I think it looks pretty good and I might give that a go.

In the tele 700 the balance circuit uses a 1uf capacitor, is there a reason you have used 2uf?

21st Mar 2016, 5:22 pm	#1
BigClick Hexode Join Date: Dec 2015 Location: Walsall, West Midlands, UK. Posts: 327	Coil Inductance No 14 Hi telephony folks, I am thinking about making a coil to convert a Bellset 1a to a Bellset1. I have some information that might help work out the guage of wire from the turns and resistance... ... two windings of 26 Ohms (1400 turns) (tags 3 & 4) and 17 Ohms (1700 turns) (tags 1 & 2). The problem would be the core. So does anyone have a coil no14 they could measure for me? Even better, does anyone have a spare coil no 14 to sell? Kind regards, Ray

21st Mar 2016, 10:27 pm	#2
PJL Dekatron Join Date: Sep 2005 Location: Seaford, East Sussex, UK. Posts: 5,997	Re: Coil Inductance No 14 Read this thread, https://www.vintage-radio.net/forum/...=119966&page=2 I came to the same conclusion about the problems in obtaining the right core material. I put a circuit at the end based on using a much more readily available 700 series induction coil and the turns ratio is close enough. PS: I have a feeling there was an error in my circuit and the line connections 5/2 should be reversed. Last edited by PJL; 21st Mar 2016 at 10:35 pm.

21st Mar 2016, 11:12 pm	#3
BigClick Hexode Join Date: Dec 2015 Location: Walsall, West Midlands, UK. Posts: 327	Re: Coil Inductance No 14 Hi PJL and thanks, Yes I came across a very old marketing blurb for the bellset inductance coil (GEC) and they go on about how the core is made from finest Swedish steal that is cold rolled to align the crystals and is then annealed etc etc. So did you body snatch from a 700 series? In the meantime I have seen this site; http://oldphoneguy.net in one of his "booklets" he describes a homebrew ASTIC circuit using a miniature transformer available from Farnell for under a fiver; TRIAD MAGNETICS TY-145P It looks quite neat and its suitable for receivers with an impedance ranging from 75 - 300 ohms I have got a couple of bellset 1a and a couple of bellset 26s so it might be worth setting one of them up up and trying it out.

22nd Mar 2016, 2:07 pm	#4
PJL Dekatron Join Date: Sep 2005 Location: Seaford, East Sussex, UK. Posts: 5,997	Re: Coil Inductance No 14 I found the 700 induction coil on ebay. Having said that it cost me the same as a complete phone I saw for £6 at an antique market.