looking for INFORMATION on Toroid cores
ant...@ksanmail.com
I notice that in the surplus Toroids that are available the cors are painted
colors probably to identify characteristics. Is there any INFORMATION available
to identify the colors as to what characteristics each color may have?
Also I have one core with numbers "A 050056-2 BH4+5" any help at decoding this?
Can anyone point me in the right direction to find INFORMATION? or?
color me curious.....
& Thanks
<ant>
WB8RCR
The bad news - iron powder toroids are painted to indicate the mix, and
hence the permeability and frequency range, but there is no standard. Most
of the toroids in amateur radio use come from Amidon, and they have 2 color
schemes, one for amateurs and one for industrial use. Ferrite toroids
aren't painted at all.
If the ferrites were scrounged from some equipment manufacturer's inventory,
there is a good chance the numbers you have are from that manufacturer, and
maybe even the colors.
If the toroids you have are mostly red and yellow, there is a good chance
that they are from ham radio stock and are probably -2's and -6's. White
(-7) is also fairly common. Other colors are rarely used in amateur radio
service.
The good news is that it's not too hard to measure the permeability. Simply
put say 10 turns around the thing, put it in series with a resistor or cap,
apply a few volts of RF across it, and measure the RF drop across the toroid
and the other component. You now know the reactance, and hence the
inductance. Unfortunately, this doesn't tell you the loss. Toroids have
useful frequency ranges, too. Outside that range they tend to get lossy.
The -2's are good from 2-30MHz, although they are generally used only below
10. They have a higher permeability than the others, and at the lower
frequencies you are generally looking for more inductance. The -6's are
good from 10-50. The -7's from 3-35. The -7's have a better temperature
coefficient than the others so they tend to be used in VFOs.
The ferrites are all a shiny black and can't be told apart by eye. They
have a much higher permeability than the powdered iron ones. In general,
they are only used in resonant circuits at very low frequencies, most are
only good below 1MHz. However, in transformer service, they aren't so
frequency sensitive, so you find them in chokes and transformers.
Oh, the handbook is the reference for hams, but the Palomar Engineers web
page has the colors for those intended for ham service. But for 99% of the
powdered iron toroids used in amateur radio service, there's not much to
know:
freq u ppm/degC
Red -2 2-30 10 95
Yellow -6 10-50 8 35
White -7 3-35 9 30
hope this helps
didleydadidah
<ant...@ksanmail.com> wrote in message news:96cmd...@drn.newsguy.com...
Scott
Scott
N0EDV
--
--Scott--
1986 Corben Junior Ace N3642
http://corbenflyer.tripod.com/
RV-4 under construction (tail feathers)
Gotta Fly or Gonna Die!
Bruce Muscolino
There is NO standard for toroid color coding. Let me repeat that -
THERE IS NO STANDARD FOR TOROID COLOR CODING. You can only depend on
color coding from a single manufacturer and even then you may be up
against special runs.
Torords are CHEAP. I'll repeat that too - TOROIDS ARE CHEAP. Go to
Dan's Small Parts and you will find assortments of toroid cores by
Amidon. Go look at the Amidon web site (www.bytemark.com) and they will
have lots of core data and also sell their cores.
Don't waste your money on surplus toroids unless you are a dyed in the
wool experimenter who does not care what he has!
73
WB8RCR
news:3A8BC5C8...@bloomer.net...
> Amidon has information at http://www.amidoncorp.com/f_ham.htm
If you rummage around on this web site, you will see exactly what Bruce said
(and I didn't say so loudly) -- 'THERE IS NO STANDARD FOR TOROID COLOR
CODING.' On this one web site there are at least 2 different color schemes.
I agree with Bruce that toroids are cheap, and I try to keep a good supply
of those I commonly use. They are cheaper at Dan's, as Bruce points out,
than pretty much anywhere else. But if you need just a few, it generally
works out better to order them at radioshack.com because of the shipping
(although it's hard to look through Dan's website without finding $100 worth
of stuff you can't live without, and for that kind of order his shipping
deal is better than radio shack's.)
But I disagree that it's important to throw away the junk ones. It's not so
tough to measure the permeability, and as long as you are suspicious of the
loss, why not? Obviously, it depends on how critical your current project
is, and how much you value your time. Just don't get suckered into
believing that because it's white it must be a -7.
didleydadidah