Rich,
*********** REPLY SEPARATOR ***********
On 2/2/06 at 2:14 AM R. Measures wrote:
>On Feb 1, 2006, at 12:24 PM, Will Matney wrote:
>
>> All,
>>
>> What has been your experience in the wide-band transformer core
>> material types available for use on 160-10 meters in both Ferrite, and
>> Iron Powder, or the types recommended to use? Available materials that
>> have been used in Ferrite is 43 and 61 material with 43 material
>> having the highest permeability of about 850u. 43 was recommended by
>> Motorola in their HF amp designs for wide band transformers. However,
>> 61 was recommended to me once because of the 43 material heating
>> quicker, or saturating, and the heat ruining the core. 61 was supposed
>> to cure this but with a loss of permability.
>
>61 begins to saturate at c. 13MHz, so the 10MHz max rating is
>realistic. 63 is rated for up to 50MHz.
>
That;s what I thought too until the Guys at Palomar Engineers mentioned using
61. Below is from Amidon;
Material 61 (µi = 125):
Offers moderate temperature stability and high 'Q' for frequencies 0.2 MHz to
15. MHz. Useful for wideband transformers to 200 MHz and frequency attenuation
above 200 MHz. Available in toroids, rods, bobbins and multi-aperture cores.
Material 63 (µi = 40):
For high 'Q' inductors in the 15 MHz to 25 MHz frequency range. Available in
toroidal form only.
Material 43 (µi = 850):
High volume resistivity. For medium frequency inductors and wideband
transformers up to 50 MHz. Optimum frequency attenuation from 40 MHz to 400
MHz. Available in toroidal cores, shield beads, multi-aperture cores and
special shapes for RFI suppression.
So 43 wouldn't be any good for 6 meters at all, they'd have to use looks to me
like 61. However, if 61 saturates at 10-13 MHz, what do you use? Would you use
a larger stack than normal to keep it from saturating or is 10-13 MHz it's
maximum limit regardless of the literature? That's my problem, what to spec as
I may have to leave out ferrite transformers all together from the app if I
cant resolve this. One place I hear one thing, and one another. Seems like I
have never seen a source for ferrite or iron powder yet on the net, or in
literature that I can trust.
>> Also, in wide band transformers, the upper frequency limit is said to
>> be 10X higher, is this the same for iron powder the same as ferrite?
>> In iron powder, the recommended types in color are Red (mix 2), White
>> (mix 7), and Yellow (mix 6). Mix 2 is .25 to 10 MHz, Mix 7 is 1 to 20
>> MHz, and Mix 6 is 2 to 30 MHz. The permeability between the three is
>> not much different so I would think using mix 6 (Ye
>> llow) would be the way to go but loose a small amount of
>> permeability. If the X10 freq rule holds true for iron powder, then
>> one could use Mix 2 (red) easily enough and gain it back. Generally,
>> in any transformer, the upper freq. is not the problem, it's trying to
>> use a core below its maximum lower frequency. That would hold true for
>> either iron powder or ferrite I would think. What would any here
>> recommend? This is for the RF transformer part of the software I'm
>> writing.
>>
>> Best,
>>
>> Will
>>
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>>
>>
>
>Richard L. Measures, AG6K, 805.386.3734. www.somis.org
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