5894	2011-03-09 06:13:52	aadlh48	mix differences between Amidon and Micrometals iron powder toroids
Message	Date	From	Subject
Hi all, I'm new to homebrewing and want to make a start with the regenerative receiver, as described in the first chapter of the EMRFD book. Now I have a question about the differences in frequencyranges on iron powder toroids from Amidon en Micrometals: From the Amidon site: https://www.amidoncorp.com/categories/8?page_number=2 Amidon 2 Material Range 2Mhz - 30Mhz Color = Red Amidon 6 Material Range 10Mhz-50Mhz Color = Yellow From the Micrometals site: http://www.micrometals.com/materials_index.html Micrometals Mix No. 2 = .25-10 MHz Red Micrometals Mix No. 6 = 3-40 MHz Yellow The regenerative receiver is described for the range 6.8 - 16MHz, which is covered by mix no. 6 from Micrometals but by mix. no 2 from Amidon. So I think when ordering from Amidon I need Txx-2 cores instead of T-xx-6 cores mentioned in the partslist. Am I right?
5895	2011-03-09 06:57:21	ehydra	Re: mix differences between Amidon and Micrometals iron powder toroi
Wasn't Amidon just the distri for micrometals? - Henry -- ehydra.dyndns.info aadlh48 schrieb: > Hi all, > > I'm new to homebrewing and want to make a start with the regenerative receiver, as described in the first chapter of the EMRFD book. > > Now I have a question about the differences in frequencyranges on iron powder toroids from Amidon en Micrometals: > >>From the Amidon site: > https://www.amidoncorp.com/categories/8?page_number=2 > > Amidon 2 Material Range 2Mhz - 30Mhz Color = Red > Amidon 6 Material Range 10Mhz-50Mhz Color = Yellow > >>From the Micrometals site: > http://www.micrometals.com/materials_index.html > > Micrometals Mix No. 2 = .25-10 MHz Red > Micrometals Mix No. 6 = 3-40 MHz Yellow > > The regenerative receiver is described for the range 6.8 - 16MHz, which is covered by mix no. 6 from Micrometals but by mix. no 2 from Amidon. > > So I think when ordering from Amidon I need Txx-2 cores instead of T-xx-6 cores mentioned in the partslist. Am I right? >
5896	2011-03-09 08:00:56	Nick Kennedy	Re: mix differences between Amidon and Micrometals iron powder toroi
I also think it's the same parts from either source. This summer I built a tube regen for 40 meters (David Newkirk design) and I used a yellow (type 6) core, just a reference point for you. The receiver works great. 73- Nick, WA5BDU [Non-text portions of this message have been removed]
5900	2011-03-09 14:19:33	Wes	Re: mix differences between Amidon and Micrometals iron powder toroi
Hi OM, and group, This "guideline" regarding cores has been around for a very long time and is generally nothing more than that. The folks who who manufacture the cores get the question "What core should I use for my frequency." Rather than talking to the customers directly, they came up with a chart. It keeps us off their back. That said, I've found that their chart is not a very good guide line. The temperature coefficient of the -6 material is much better than -2 for all frequency. More often than not the Q is better, even when operating the cores at frequencies below the guide line. The higher permeability of the -2 means that it will take fewer turns to realize a coil, but only by a little bit. When Bill Amidon started his little company, all he did was to buy cores from the manufacturers and sell them to the hams, and others, in small quantity. He started with powdered iron parts and later added ferrites. Bill has since died, but the business continues. I can't imagine that they manufacture anything themselves. I've always worked under the impression that they remain merely a distribution and marketing company. The company was a joy to deal with back when Bill was alive. One of the other themes that will emerge from the book is that experimentati
5901	2011-03-09 20:27:39	Craig D. Smith	Re: mix differences between Amidon and Micrometals iron powder toroi
Amidon does not manufacture cores - they are just a reseller of standard parts from MicroMetals, etc. The "recommended" frequency ranges for the various core types are fairly broad and subjective, are application dependent, and overlap each other to a large extent. Either the 2 or 6 mix should probably work just fine for this project with the appropriate adjustment in the number of turns to achieve the same inductance. Since this is the case, I'd recommend staying with whatever was specified in the article. A very good source for all these types of cores is www.kitsandparts.com. I have no affiliation with them, but they will deliver the same thing as Amidon at significantly lower prices. Have fun with the project! 73 Craig AC0DS
5902	2011-03-10 07:00:20	Tim	Re: mix differences between Amidon and Micrometals iron powder toroi

5920	2011-03-16 03:29:50	aadlh48	Re: mix differences between Amidon and Micrometals iron powder toroi
On the Amidon website https://www.amidoncorp.com/ is a list 'Brands We Carry' but Micrometals is not on that list. I send Amidon an email with the question from which brand their iron powder cores are but didn't get an answer on that. So it's not clear to me if Amidon sells cores from Micrometals, and if they do it's strange they are advertising much different frequency ranges. However, I understand it's not that important for the application in EMRDF's regenerative receiver. Thanks for the replies.
5921	2011-03-16 06:20:15	kb1gmx	Re: mix differences between Amidon and Micrometals iron powder toroi
I don't recommend any ferrite for the coils in a regen at least for the coil used for the feedback portion. Elsewhere it's very useful. The reason is the right ferrite gives an good Q but an air core can do much better. Also the coupling needs to be loose or at least the right value and ferrite leads to tight coupling almost by default and the turns radios are less than optimum. Every time I've tried it the radio exhibited hysteresis right around the margin of regeneration to oscillation. It's generally better if the circuit slides smoothly in an out of regenerati
5923	2011-03-16 13:34:20	davidpnewkirk	Re: mix differences between Amidon and Micrometals iron powder toroi