DIY IF Cans for Valves

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Re: DIY IF Cans for Valves

Post by Ivan on Sun Aug 10, 2014 8:38 am

Hi all,
my experience is that a decent LC meter is a must for a ham dealing with radio.

BR from Ivan OK1SIP

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Re: DIY IF Cans for Valves

Post by Runem on Sat Aug 09, 2014 9:52 am

It's simply impossible to get 1.5mH with only 68 turns on an air core former with those measurements, so it must be 345 turns that is correct. If the former has a ferrite core things are starting to look quite different. The best thing to do in that case, in my opinion, is to buy or built yourself a LC meter, wind a lot of (too many) turns of wire on the former that's thin enough, and then start to unwind and measure the inductance as you go along.

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Re: DIY IF Cans for Valves

Post by rjfrediani on Wed Jul 23, 2014 11:49 pm

It appears to me that the equation given is not correct, at least for mm.  The similar equation I found was for entries in inches.

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DIY IF Cans for Valves

Post by rjfrediani on Tue Jul 22, 2014 8:35 pm

I found this article on line by Harry Lythall and its going to help me figure how to replace the 1st IF transformer on an old radio.  I'm having trouble with the table that calculates the turns required.  The results using the table do not agree with the results from an Excel spreadsheet for the formula.  For example, if I enter 1500 uH, Former diameter = 10mm, Winding Length = 10 mm, Winding depth = 10 mm, then the table says 345 turns.  In my spreadsheet the answer is 68 turns.  I found a slightly different equation for turns (arithmetically identical) and I also get 68.  So my question is: Has the table been verified to be correct?

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