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Author Topic: 45 MHz IF Transformers  (Read 4839 times)
TANAKASAN
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Posts: 933




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« on: February 12, 2012, 05:02:14 AM »

Does anyone know of a source of 45 MHz I.F. Transformers? A Google search found a place in Australia but these were not the real deal.

Tanakasan
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G3RZP
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« Reply #1 on: February 12, 2012, 05:11:33 AM »

Find an old valve TV set. They'll have 38 MHz (approx) transformers you can pull up. Or make your own - not difficult.
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AC5UP
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« Reply #2 on: February 12, 2012, 09:52:13 AM »

Standard IF frequency for US TV's was 45 MHz, and that was true from the rotary dial era through the VCO / PLL synthesized models......... VCR's, too, but on the most recent analogue designs the tuner is a miniature brick loaded with SMT parts and a complete lack of anything adjustable. Seems that I recall they tune by a data line, too.

In any case, a decent US thrift shop would have no problems providing all the salvaged IF cans you could want and every one of them will have a bandpass wide enough for NTSC video with an audio subcarrier at 4.5 MHz. Translation: It's a barn door with tuning slugs.
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Never change a password on a Friday                
G3RZP
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« Reply #3 on: February 14, 2012, 05:21:08 AM »

I think I'm right in saying Tanakasan is over here....
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KB9JXZ
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Posts: 36




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« Reply #4 on: February 14, 2012, 04:32:38 PM »

 For what it is worth, I have had good luck with older VHF/UHF FM crystal type radios that had a 45 MHz I.F. and then the 10.7 MHz I.F.   The last ones I pulled were from an old Johnson VHF radio and it had three of them.  On the top of the can it said "TOKO RCL"  and on the side it had four lines of print. First line = 1013, second line = 001, third line = 8626, fourth line = HK. Aprox. 3/8 square and about 9/16 tall.

 73
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W9GB
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Posts: 2659




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« Reply #5 on: March 16, 2013, 10:56:19 PM »

Circuit Specialists.com IF Transformers 42Lxxxx, appear to be Xicon
http://www.circuitspecialists.com/high-quality-if-transformers

Make Your Own IF Transformers.
It's easier than you think.
http://www.angelfire.com/electronic/funwithtubes/IF_Can-1.html

Good tutorial on Xicon/Mouser IF cans
http://www.electronics-tutorials.com/filters/if-amplifier-transformers.htm

Xicon IF transformers - Mouser
http://www.mouser.com/catalog/catalogusd/645/2855.pdf

DIY IF cans for Valves (Vacuum tube)
Harry Lythall - SM0VPO
http://www.sm0vpo.com/blocks/if-txfmr_tube_00.htm

Vintage Datasheets (scanned) for Transformers & Coils
by Jeff Duntemann
http://www.junkbox.com/electronics/vintagedatasheets.shtml
« Last Edit: March 16, 2013, 11:30:17 PM by W9GB » Logged
TANAKASAN
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Posts: 933




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« Reply #6 on: March 17, 2013, 04:27:57 AM »

Thanks for the links although this is now a very old topic. Most of the links point towards 455 KHz or 10.7 MHz transformers but three of the Mouser devices MIGHT work as they come without capacitors. What I ended up doing was using some Minicircuits transformers and instead of having a variable inductance and fixed capacitor I used a fixed inductance and a 20pF trimmer.

Tanakasan
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W9GB
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Posts: 2659




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« Reply #7 on: March 17, 2013, 07:59:13 AM »

Joseph Carr's book, RF Components and Circuits, pages 176-177
 discusses the 45 MHz IF by taking that approach (IFT cans w/o capacitors).  

45 MHz was also the common IF used in TV receiver designs for a number of years.
« Last Edit: March 17, 2013, 08:09:20 AM by W9GB » Logged
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