Barett wrote:

What is the T200-2 Toriod used for and why is it good for that purpose?

Tuned circuits e.g. antenna matching & filters, that's about it !

#6 is even worse for HF broadband transformers

Too many folks use iron powder cores of all types for totally
unsuitable purposes.

UKM

Does any one know where I can purchase some Ferrite rings type 31
material from in the UK?

and thanks to UKM.


UKM is right: iron powder material is not suitable for RF chokes.

Well done for finding out about Fair-Rite 31 material - you must have
been reading Jim Brown K9YC's tutorials on www.audiosystemsgroup.com
:-)

None of the UK amateur suppliers seems interested in stock large toroids
or beads in this material (and believe me, I have tried) so the next
best thing is to order from the USA.

As Jim Brown has often advised, order directly from an industrial
supplier in the USA, and not one of the "amateur" suppliers. When
ordering from outside the USA, the most cost-effective route is probably
either Mouser or Farnell because they handle the international shipping
and Customs clearance, so you don't get hit for the same one-off charges
and 'collection fees' that a personal import would.

There is no import duty on these electronic parts, but of course you
still have to pay 17.5% VAT on the whole bill.

The best value will depend on the size of your order, and of course on
any special offers, but it's sure to be cheaper than any of the US
amateur suppliers like Amidon. Mouser have a free Fedex shipping deal on
orders above GBP50. Farnell can supply US stock from their Newark
Electronics affiliate with an extra charge of GBP15 per order (they
removed this charge for the whole of January, and maybe this offer might
be repeated).

The Fair-Rite part number for the 2.40in #31 toroid is 2631803802. Paste
this number into the search fields at http://gb.mouser.com and
http://uk.farnell.com and search out the best deal.

Ah, too bad... Mouser currently have an 11 week lead time.

Farnell have 95 of them at Newark Electronics. (Ignore the wrong
information about "43 shield beads". Farnell/Newark confirmed that the
cores really are #31, but it may take some time to correct the web
page.)

Also worth considering is the giant #31 clamp-on bead 0431177081... an
exercise for the reader.



--

73 from Ian GM3SEK 'In Practice' columnist for RadCom (RSGB)
http://www.ifwtech.co.uk/g3sek