eHam
eHam Forums => HomeBrew => Topic started by: WT1V on February 03, 2023, 11:44:26 AM
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Looking at a project in QST I find that I needed a T-130 and a T-68-2 toroid cores. I can't find anything like this on EBay! Digikey is no help. Anybody have any ideas where to look for these items?
73 wt1v
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https://kitsandparts.com/toroids.php
This will help.
Barry, KU3X
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https://www.amidoncorp.com/
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https://palomar-engineers.com/
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Amidon = WAY too much money. I've always bought in small quantities from either Mouser: http://www.mouser.com (http://www.mouser.com) or Digikey: http://www.digikey.com (http://www.digikey.com)
No minimum order but shipping can be high on small items so best to find other things which you can use while there.
I've bought many toroids from Mouser and quality was always good.
EDIT: On rereading I see that you already tried Digikey. Sorry that they coulodn't help :(.
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Maybe Octopart can help. I use site for Fair-Rite partsL
https://octopart.com/
GL
73 Kevin N2TO
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Just checked ebay (ebay.ca), lots of T-130-2 and T-68-2 toroids listed at various prices.
GL
Dave, VE3WI
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Mouser USED to provide small packet shipping for small items...if you asked. (Approx. half of the normal shipping.) FWIW.
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The kitsandparts link was VERY helpful!
Since the QST transmatch article refers to T-130 and a T-68-2 toroids I find the last parameter refers to a mix which might be referencing the permeability of the core material. Looking at the link above I see that the -6 toroid will cover the ham band, so I think that is what I'm looking in this circuit. The T-68-2 is used for directional coupling so I believe that a -6 core should be used instead of the -2 core.
73 wt1v
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That numbering scheme is used by Amidon.
Powdered iron toroids have a "T" prefix, while ferrite has "FT".
The next number is core diameter in 100ths of an inch. The
last, as you discovered, is the "mix" that describes the material.
Futher information. (https://www.amidoncorp.com/iron-powder-toroids/)
For powdered iron cores, #2 mix (red) is rated for 2 - 30 MHz,
and #6 mix (yellow) is rated for 10 - 50 MHz. In practice,
#6 cores can be used on 40m as well. So if you only want
to cover 40 - 10m, then a T-130-6 core is probably acceptable,
although it will require more turns for the same inductance.
(But if the original design covered down to 80m, you won't need
as many turns if you only need it down to 40m.) So there will
be a bit of readjustment of the number of turns for each tap
point if you are trying to reproduce the original.
The core size required will depend on the power level: for QRP
work you can use a smaller core (again, it may require a change
in the number of turns).
Note that, for ferrite parts, Amidon originally resold cores from
FairRite, and used their mix numbers (#43, #31). But in the last
few years the appear to have shifted to other suppliers, and the
materials don't have the same characteristics as the original
FairRite types. Digikey, Mouser, and other commercial vendors
sell the FairRite parts under the FairRite part numbers, rather than
under the Amidon numbering scheme. So you would look for a
FairRite #2631803802 (https://www.fair-rite.com/product/round-cable-emi-suppression-cores-2631803802/) rather than an FT-240-31.