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Old 10th Sep 2021, 6:13 pm   #1
radiograham
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Default Winding TV IF transformers.

Hello all,1950s home built tv circuits are mostly trf designs for simplicity,i wondered if anyone knows of a s/het design that gives constructional details of the if transformers,i am trying to reconstruct the rf deck in a philco bt1840 which i tried to convert to 625 lines years ago,the original coils are long gone i'm afraid.the original if frequencys were vision 13mhertz sound 10mhertz,i have a lot of 1950s p/television mags but have'nt come across anything yet. Graham.
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Old 10th Sep 2021, 7:24 pm   #2
Ed_Dinning
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Default Re: Winding tv if transformers.

Hi Graham the earlier edition of Newnes Practical Television Circuits has details of the PT Lynx superhet circuit including coil winding details. That should be a good starter.
If you can get hold of something like the Advance Q meter it assists greatly in winding RF coils and transformers

Ed
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Old 10th Sep 2021, 11:18 pm   #3
radiograham
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Default Re: Winding tv if transformers.

Hi Ed,thank's for the reply,i think i remember the lynx tv but can't remember what the if frequencies were,do you know where i can find the newnes practical tv circuits book?is it online do you know. Graham.
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Old 11th Sep 2021, 11:47 am   #4
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Default Re: Winding TV IF transformers.

If you're planning to use aladdin type formers there are tables showing inductance and number of turns for various wire gauges in the back of 1950\190 Rsgb handbooks.
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Old 11th Sep 2021, 1:40 pm   #5
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Default Re: Winding TV IF transformers.

Hi!

I think the P.T. "Lynx" was published in the early 1950 issues of "Practical Wireless" before Practical Television was introduced in April 1950 as a separate Magazine!

I have an early copy of "Practical Television Circuits" by F.J. Camm buried somewhere, but I can't just lay my hands on it at the moment!

Early Superhet T.V. I.F.'s commonly employed were:–

a) 13 MHz vision, 10.5 MHz sound;
b) 19.5 MHz vision, 16 MHz sound;

The final 405-line standard I.F.'s were 34.65 MHz vision, 38.15 MHz sound (I think they were that way round, please correct me if I'm wrong!).

Chris Williams

PS!

Both the 1954 and 1968 Editions of "Practical Television Circuits" used to be online, but I fear some copyright mogul spoilsport has complained and had them removed!
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Old 11th Sep 2021, 2:18 pm   #6
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Default Re: Winding TV IF transformers.

Oh another person building a TV, awaiting with interest.

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Old 11th Sep 2021, 2:41 pm   #7
Chris55000
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Default Re: Winding TV IF transformers.

Hi!

Here are the four 1953 Issues of P.T., covering the "Lynx!"

https://worldradiohistory.com/UK/Pra...on-1953-05.pdf

https://worldradiohistory.com/UK/Pra...on-1953-06.pdf

https://worldradiohistory.com/UK/Pra...on-1953-07.pdf

https://worldradiohistory.com/UK/Pra...on-1953-08.pdf

To the best of my knowledge, there was the P.T. Televisor, the "Argus" from 1952, "A Beginner's T.V. Receiver", there was also "Miniature Portable TV Receiver" (1951/1952) that I think was designed by a teenager, the "Lynx", the 'Supervisor", the 1960 all–valved "Olympic", and the "All–Transistor Olympic", by D.R. Bowman from 1965, then the last b/w design using valves was the "Constructor's 625-line Receiver, Keith Cummins, 1969/1970!

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Last edited by Chris55000; 11th Sep 2021 at 2:50 pm.
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Old 11th Sep 2021, 4:43 pm   #8
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Default Re: Winding TV IF transformers.

I believe all the ones mentioned by Chris up to the supervisor are in a book called Practical Television circuits by F. J. Camm. This was basically a reprint of the articles from the Practical Television magazine.

Before I got the book I used these same references to build an electrostatic TV version for myself.

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Old 11th Sep 2021, 5:31 pm   #9
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Default Re: Winding TV IF transformers.

Hi!

As I mentioned, the 1960 Valved "Olympic" was only in the magazine, the 1965 battery/mains portable "Olympic" was in the 1968 edition of "Practical Television Circuits", and the "Constructor's 625-Line Receiver", 1969/1970, was also only in the mag, and additionaly, there was also "TV Circuits for the Constructor" (1972) that featured both 405–line and 625–line experimental circuits to try as well, but it didn't provide a fully worked out design!

All free from W.R.H!

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Old 11th Sep 2021, 6:53 pm   #10
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Default Re: Winding TV IF transformers.

Hi Gents, see the sale section. I find I have a spare copy of this book, so advertised there

Ed
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Old 11th Sep 2021, 10:17 pm   #11
radiograham
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Default Re: Winding TV IF transformers.

Thank's for all the replies,i have found the issues of practical tv covering the lynx on the american radio history web site.Graham.
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Old 26th Sep 2021, 8:23 pm   #12
radiograham
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Default Re: Winding TV IF transformers.

Progress so far on this,dug out the tuner unit on a murphy v202 chassis i had,this is 2 rf stages and f/changer a 6c9 triode hexode,this was a channel 2 type.the if stages for this were complete apart from the first if transformer which suffered a blow at some time and was snapped off.I examined this and wound a replacement,i have this working at the moment using my aurora on ch2 with the output of the if strip into a sony 9-90ub using another modulator.The results are the testcard c from the aurora is ok but distorted in some way,the circle has jagged edges in horizontal position,i think this is called cogging?on a picture this is less pronounced.I am hoping this is due to the unusual set up ie the two modulators,i will refit the rf unit into the philco tv and see. Graham.
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Old 29th Sep 2021, 11:20 pm   #13
radiograham
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Default Re: Winding TV IF transformers.

I have this if strip working now being fed from a dvd player into a modulator with the video from if strip feeding one of those teleton tvs with video in.I made a quick tape of test card c with a camcorder,this plays ok with none of the distortion.I was pleasently surprised to find that the original first sound if coil was still present on the chassis albeit with a seized core which will have to be drilled out as there is no slot left. Graham.
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