beginner wrote:

It is FT82-75 and the resistance is only 5 KOhm, so the mix is accurate.

I will have to make use of them in wideband tranmission transformers.
Can you folks suggest a frequency range?

I can get ferrite #61 or #63, but iron core only comes in mix #2 or #6
locally.

Mix #2 should be OK for your crystal set.

With a transmission line transformer you should be able to go up to 100
MHz or more, the core is only important at the lower part of the
frequency range.

Leon
--
Leon Heller, G1HSM
Email:
My low-cost Philips LPC210x ARM development system:
http://www.geocities.com/leon_heller/lpc2104.html

beginner wrote:

Yes it is definitely a core T82-75 from the labeling on the package.
Which parameter specifies that it has low resistivity?
Can this be used as a transmission line transformer of a balanced mixer?

Which ferrite material works well for the AM band around 1 MHz?

I can get core #43, 61, and 63.

Thanks for the input folks.

Go to the makers catalog (available as a big PDF) at:
http://www.fair-rite.com/fr_catalog-14thed_rev3.pdf
and read about the various types (starting with the parametric
comparison on page 4, including the frequency recommendations under
the low flux density row). Type 43 is normally used in RFI absorbing
devices but has pretty good properties for indictors for low flux
applications up to 10 MHz. Type 60 is recommended for up to 100 MHz,
and type 63 isn't a Fair-Rite type listed in this catalog. In the
same table type 75 is limited to .75 MHz for low flux applications.
Based on this table, alone, I would probably try the type 43.

--
John Popelish

Which ferrite material works well for the AM band around 1 MHz?


Here's what seems like a hi-Q a crystal set using toroids:
http://www.crystalradio.net/contest/paul.html

It uses "two toroid cores, Palomar Engineering T-130, broadcast band
frequency material". Unfortunately it doesn't say the kind of core, but from
the number of turns and the capacitance I figured that it must be type 26
(yellow/white). I think this is a rather uncommon kind of material, it has
one of the highest mu's, 75, compared to mu=10 for type 2 and mu=8 for type
6. Anybody with experience with this kind of material?

Sverre
LA3ZA

In article ,
beginner wrote:
It is FT82-75 and the resistance is only 5 KOhm, so the mix is accurate.

I will have to make use of them in wideband tranmission transformers.
Can you folks suggest a frequency range?

I can get ferrite #61 or #63, but iron core only comes in mix #2 or #6
locally.

Thanks for all the help!

Digging out an old Amidon spec. sheet, they used #61 and #33 for their
ferrite (antenna) rods. Type #61 for medium wave and up to 10 MHz, and
type #33 for VLF.

The real question is "Are you using it in a tuned circuit?", where you
want the coil loss to be negligable. If you're making an antenna coil
that's tuned with a capacitor for AM broadcast (.54-1.7 MHz), use the
type 61.

For wideband transformers, where frequencies are higher than tuned
circuit use, Amidon specs type 61 as good for 10-200 MHz, and type 63
as good for 25-200 Mhz. For HF use #43, #77, #72, or #F.

Mark Zenier Washington State resident

A good mix is 61, There is a winding table for the different cores located
at www.crystalradio.us
Also there are plans listed. Cores are a easy way to get a respectable Q.
The worldwide crystal set contest starts this weekend look for info at the
site




"beginner" wrote in message
...
I made an inductor by winding 14 turns on T82-75 torroid.
Using 180 pF variable capacitor, in a crystal radio circuit I could not
pick up any signal but even with a 470 uH modded inductor I picked up a
few
signals.

Is this material not suitable for this appication?

Thanks