Hi

I'm building a Carolina Windom 80 Special. 66 feet long (25ft one side 41ft
the other with a 4:1 balun at the off centre, 10ft coax down to a RF choke.

My question is. Can I use a FT200-2 RF Toroid wound with coax to make up a
choke to use as the choke?

Thanks

"Barett" wrote in message
...
Hi

I'm building a Carolina Windom 80 Special. 66 feet long (25ft one side
41ft the other with a 4:1 balun at the off centre, 10ft coax down to a RF
choke.

My question is. Can I use a FT200-2 RF Toroid wound with coax to make up a
choke to use as the choke?

Thanks


I made a mistake in the Toriod number. It is infact a T200-A.

I have found the answer I was looking for on a web site. See belowe. It
might help some one else with the same ideas of using this a choke.

My recommendation is to pick a different material. T-200-2 is a powered iron
material; the permeability is way too low to build an effective
coaxial-cable choke with. The AL value is 120 (meaning it takes 120 turns to
make a 100 uH choke).

You should be looking at ferrite, probably mix 31, 43, or 61. Mix 31
requires the fewest turns.

I have another question.

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

Thanks

On Feb 9, 8:40*am, "Barett" wrote:
"Barett" wrote in message



I have another question.

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

"UKMonitor" wrote in message
...
On Feb 9, 8:40 am, "Barett" wrote:
"Barett" wrote in message



I have another question.

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.

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

"Ian White GM3SEK" wrote in message
...
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

I only need about 3 of them I think, so the postage is a killer
unfortunately.

I have found some FT140-43's.

Do you know if I stacked 3 Ferrite FT140-43's rings and wound 6 winding of
RG58cu through, what would the maximum impedance Ohms could I expect @
3.5MHz?

Also how much impedance could I expect to gain every time I added another
FT140-43 ferrite onto the stack?

Thanks for you links and info.

On Feb 9, 3:33*pm, "Barett" wrote:
"Ian White GM3SEK" wrote in ...





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 onwww.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 athttp://gb.mouser.com*and
http://uk.farnell.comand 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

I only need about 3 of them I think, so the postage is a killer
unfortunately.

I have found some FT140-43's.

Do you know if I stacked 3 Ferrite FT140-43's rings and wound 6 winding of
RG58cu through, what would the maximum impedance Ohms could I expect @
3.5MHz?

Also how much impedance could I expect to gain every time I added another
FT140-43 ferrite onto the stack?

Thanks for you links and info.- Hide quoted text -

- Show quoted text -

Take a look at

http://www.karinya.net/g3txq/chokes/

http://audiosystemsgroup.com/RFI-Ham.pdf

http://www.yccc.org/Articles/W1HIS/C...S2006Apr06.pdf

Mouser and Newark are you only real options, watch out for special
shipping offers and take advantage of them when they occur.

The giant #31 clamp-on beads 0431177081 are expensive but equivalent
to three 240 sized rings.

UKM

Also how much impedance could I expect to gain every time I added another
FT140-43 ferrite onto the stack?


You need to double the number of beads each time to make a noticable
difference.

For worthwhile common mode suppression you need at least ten and
ideally eighty type 43 beads over a length of cable.

It's more cost effective to wind more turns. 2 x the turns 4 x the
inductance.

UKM

For the 4:1 Ruthroff balun Type 43 or 31 is not ideal for this
purpose, use approx 12 bifilar turns on a FT240-61 core.

Wind the transformer with twin figure of eight speaker cable which is
OK for low power up to about 100w. Use thin 100 ohm twin feeder sold
by Spectrum Communications for higher power levels.

UKM

On Tue, 9 Feb 2010 15:33:57 -0000, "Barett"
wrote:

Also how much impedance could I expect to gain every time I added another
FT140-43 ferrite onto the stack?

Hi OM,

Z varies by the square of turns THROUGH the center (turns are always
integers, not fractions). Z is a function of formulation (the mix of
the ferrite) which defines the optimum band(s) of operation. Z is
also a function of mass, but it doesn't take much, a small bead that
comfortably girdles RG58 will present several 10s of Ohms Z. Z is a
function of frequency, but most ferrites exhibit very mild shifts in Z
as frequency changes. You can chain beads or toroids to build up your
Z. You typically want your choke at least 3X the Z of the feedpoint -
10X is very much more preferred.

As for resources and cost, go to your nearest computer monitor
recycler and obtain any deflection coils that may still be around in
this era of flat screens. They have been reportedly quite useful.

If you do this, you will have to characterize the formulation of the
available ferrite through experimentation. If you have an antenna
computerized analyzer, you can measure this directly. If not, this
may take invention and thought (and more posts here).

73's
Richard Clark, KB7QHC