Need ferrite rod

I'm a bit suprised to see they sell a 27" x 1" ferrite rod for $90.00. I have never heard of one that long in one piece. I don't know what your project is, but it might be cheaper to use a bundle of smaller rods or stack toroids to get the length you need. Maybe even slip a small rod into the center of the toroids. You can stack potcores too, maybe fill the potcores with a toroids. Since it is a rod you have a large gap anyway, so what is a small gap here and there. Years ago a recieved a box of potcores that were broken and unusable for their intended purpose, I stacked a dozen or two with one turn through them and measured over 4000 ohms at 1Mhz. Mike

Amidon?

Check to see if you can find a Fair-Rite dealer that has it?

Use a great big ferrite bead or stacked toroids, and pretend they're not hollow?

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www.wescottdesign.com

When I was in Okinawa in the USAF (ca. 1970) I had a buddy who was a ham. He built a kilowatt grounded-grid amp using surplus components, except the

4-400A, which I stole for him out of "bench stock". (one of our jamming transmitters had a series-modulated magnetron.) Anyway, in the surplus stuff were a bunch of coils or transfomrers that had ferrite slugs about 1" diam. and about 1" long. For the filament choke, he glued 7 or 8 of them together lengthwise. It seemed to work, at least at 7-ish MHz (20 meter band).

Oki had a surplus store practically on every corner, from used/abandoned WWII stuff - a radio hacker's dream! :-)

Good Luck! Rich

20 meter band is 14.0 - 14.35 MHz

I used a bundle of AM radio ferrite loopsticks for the filament chokes in two grounded-grid linear amplifiers: one with a pair of 4-250A's and the other with a pair of 3-500Z's. The latter was built in 1972 and it is still usable.

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Tauno Voipio, OH2UG (and MSEE)
tauno voipio (at) iki fi

Stack some toroids and ignore the fact they're hollow?

I think Amidon sells big ferrite rod to use as plate and/or cathode chokes in linear amplifiers -- check. Surplus Sales of Nebraska (I think it's

has a bunch of not-so-surplus parts for linear amps; they may have choke cores, too.

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www.wescottdesign.com

D'oh! Well, in my defense, it's been a while.

Kewl!

Thanks, Rich

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=A0 =A0 =A0Mike- Hide quoted text -

Thanks for replies everyone. It appears to me that the cores are actually 1"dia by 1.12" long. He sells them without the plastic covering - scroll down to the bottom of the page. I'm guessing that he glues them end to end or spring loads them in the tube in order to get the long lengths for antennas. I'm going to have to try one of his big ones out for AM DX.

I've been working directly with Fair-Rite and they can create the larger diameter parts in 1" length as well. I'm guessing there is a limit to the ceramic technology which limits the actual size of the part. Maybe the stuff is compressed in a press???

I've ordered a few of the 1.12" parts to prototype my converter, and I'll work with Fair-rite when I go into production.

thanks-again.

regards, Bob N9NEO

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2. > > I have never heard of one that long in one piece.

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=A0 =A0 =A0Mike- Hide quoted text -

Unless I'm missing something in your argument, there certainly are long rods of ferrite. They show up all the time on ebay. The problem is no specs.

On Wed, 9 Dec 2009 06:57:23 -0800 (PST), Yzordderrex wrote: . . .

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I don't think so; the limits seem to be imposed by financial
considerations.