[RFI] Solar panel RFI

[Dave (NK7Z)]

Jim,

That is most interesting material, thank you!  Will you all be including 
a test fixture description as well?  I am in the process of gathering 
the materials to build a test fixture, and would like to see your designs...

73, and thanks,
Dave (NK7Z)
https://www.nk7z.net
ARRL Volunteer Examiner
ARRL Technical Specialist, RFI
ARRL Asst. Director, NW Division, Technical Resources

On 2/20/22 12:28, Jim Brown wrote:
> On 2/20/2022 4:13 AM, Hare, Ed, W1RFI wrote:
>> The toroids are not marked, so it will not be certain what material 
>> they are."
> 
> Thanks. For the next Handbook, I've given Ward details of a method to 
> identify a few MnZn ferrite materials with an ohmmeter. It was first 
> suggested by W1HIS, and I fleshed it out a bit further. It's pretty 
> simple. It worked with the three VOMs in my lab -- a Simpson 260, a 
> Fluke 8060A, and a nice little no-name digital VOM that I bought for 
> about $15 at a northwest Indiana hamfest at least 20 years ago.
> 
> With the meter on a high range scale, aggressively scratch the surface 
> of the ferrite with the probes so that they get through the coating, and 
> note the reading, if there is one. #31, #75, #77, and #78 are MnZn 
> mixes, and will show a reading in the range of 100K - 700K; #75, #77, 
> and #78 will be in the range of 1K - 10K. #43, #52, and #61 -- are NiZn 
> materials, which have MUCH higher bulk resistivities, and will show no 
> conductivity at all. These resistivity values, as well as initial 
> permeabilty (mu at low frequency) are tabulated in early pages of the 
> Fair-Rite catalog.
> 
> We're also including methods to zero in on the specific material 
> measuring inductance using traditional methods or studying the shape of 
> an impedance sweep with a well calibrated Vector Analyzer.
> 
> These methods, of course, depend on knowing AL or ui values for the 
> various materials. Fair-Rite's published data is FAR more extensive than 
> any other manufacturers; others publish little more than marketing or 
> limited applications data. For example, Laird (used to be Steward) 
> publishes ui values for only two of about eight materials.
> 
> 73, Jim K9YC
> 
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