Philco choke questions - Printable Version

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Philco choke questions - ValveTones - 12-09-2017

Hello everyone, i recently acquired a couple of chokes from a fellow who says that they came from a philco model 68.
I've searched the web high and low and cannot find anything. closest i can find is a 680x. 

The chokes are
1.   3422-J   6.5hy at 150mA 200 ohms dcr

2. 3518-J   150 hy at 10mA 4000 ohms dcr

So i have a few questions related to the 3518-J

What does the "J" indicate?
Which part of a circuit would require a choke with such a large henry value, such a low milliamp rating, and such high resistance? 4K is huge.

Also, does anyone know if there ever was a model 68?

Thanks for sharing your thoughts.

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RE: Philco choke questions - klondike98 - 12-09-2017

Welcome to the Phorum!


I do not believe there was ever a Model 68 for the US.  There was a Model 68 for Canada that does not have a US equivalent.  See Ron's listing:  http://www.philcoradio.com/images/phorum/canindex.pdf

Those part numbers, although without the J show up on Chuck's Philco Repair Bench site (in the waybackmachine archive https://web.archive.org/web/20170227112415/http://philcorepairbench.com/choke.htm ) in the component values but I don't know what set they would go with.  

The Model 66 US set uses a healthy choke ( #48 on the schematic http://www.audiophool.com/Philco.html ) but others can offer more info on sizes and uses I'm sure.

update: A 3244 choke is used in the Philco Model 15 (part #57 on the schematic at http://www.philcoradio.com/images/phorum/schem/15.jpg or also http://www.audiophool.com/Philco.html )

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RE: Philco choke questions - ValveTones - 12-09-2017

Thanks Bob, yeah the 3422 looks like a great choke, nicely spec'ed for many audio projects. Philco apparently used Jefferson for their transformers in the early days, and i must say, i haven't seen a nicer looking piece of iron. They seem to be extremely well constructed.  

The 3422 i can easily find a job for, its that other mut, the 3518 that i am wondering about.
With values like it has ( 150hy @ 10 mA and 4k dcr ) it would seem easy to assume it must be some space station part that i would never find a use for. 

However, being as though it is so nicely constructed, i would hate to get rid of it without knowing its purpose.
Maybe philco engineers did something really clever with this part, my aim is to find out if i'll be missing out on any glorious audio achievements by assuming (do to the specs) that this part is totally useless.

I've had to kick myself before getting rid of unknowns like this. Trying to exercise a different mindset you know.

BTW- i checked out that model 15 schem, and see that the 3422 was used in a capacitor input filter set up. 

I've been trying to figure out how to properly apply the choke input filter setup as i have several builds under class A consideration.   But need to figure out how to do this with a fixed value choke rather than a swinging choke.

Anyhow, Thank you Bob for your reply. 

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RE: Philco choke questions - klondike98 - 12-09-2017

glad I could provide some info. You sound like you know a lot more than I do about chokes and their uses but there are some others on here who can probably answer your questions so hang in there while others chime in.

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