[Elecraft] OT: Ferrite Identification Question

[James Bennett]

Hi Dan,

No problem. First, please understand that (1) I’m not an EE, and (2) I’m not an expert with the 4170C. I’ve had it a year or so and am comfortable with most basic measurements it can do, but this device is capable of a LOT more than I understand!

OK, I assume that you’ve got a 4170 and have some rudimentary knowledge in how to use it. The first thing you’ll need to do is to be sure you have a way to connect bare wire to the AIM. As you know, it has an SO-239 UHF connector on the front, so that’s a problem. I bought an adapter that is quite similar to the device on the elecraft web site called a BNC-BP: BNC Male to Stackable Binding Posts. You will need something similar, but one with a PL-259 / UHF connector on it, NOT the BNC.

Next, use this adapter to build a special CAL file. You probably are aware that you need three things for a CAL: an open (that’s easy - nothing connected to the binding posts), a short (again, easy - short piece of bare wire), and a resistance. I used a pair of 100 ohm resistors in parallel (for 50 ohms). It doesn’t have to be 50 ohms, but whatever resistance value you use has to be entered on the custom cal screen. I suggest naming this cal file and saving it for future use.

Once you’ve built your custom cal file, you’re almost ready to go. Make up a length of wire long enough to pass through the ferrite in question - pass it through only once. More than that really will skew the results. Make this wire as short as possible, and connect the bare ends to the binding posts. 

Here is where you will need to experiment. The Fair Rite pages show the impedance (Z) at several different frequencies. I currently am measuring a couple of the square “clamp on” / “snap on” cores. They measure about 1-1/4 inches in length and about 5/8 inch square. They were in a box marked mix 43. I set my AIM Setup—>Plot Parameters to show me Series Load (Rx) and Phase. I have my Limits set to 20 and 30 MHz, as I want to see the impedance at 25 MHz, which is one of the values shown in the Fair Rite tables for Mix 43/44 clamp-ons. You can set it at whatever you want, but know that the tables only give you a small handful of frequency values. Anyway, I’ve got my Scales value for Zmag set at 200 in the AIM. When I run a scan on this particular snap-on core and look at the Zmag it shows at the 25 MHz mark, I get a value of 160.652, which isn’t too far off of what Fair Rite shows for a core with these dimensions: 161 ohms. 

I was pretty sure when I started that this was a mix 43 core, and the measurements pretty much proved it right. Had I begun with no idea, it would have taken a tad longer to figure it out. So, as I mentioned, it’ll take some playing around with the Scales & Limits settings and some careful physical dimension measurement of the core(s) in question. 

Bottom line is - yes this works pretty well. No, I would NOT want to spend my day doing this for a living - it is a PITA!!

Hope this helps. 73, Jim / W6JHB



> On   Thursday, Jun 4, 2015, at  Thursday, 11:00 AM, Dan Boardman <dan.boardman at shreditfast.com> wrote:
> 
> Jim - I would be interested (if it's not to much trouble) as to how to use the AIM-4170Canalyzer to figure the ferrites and etc. that I have that are not identified.
> 
> Thanks much
> 
> Dan NB1C
> 
> -----Original Message-----
> From: Elecraft [mailto:elecraft-bounces at mailman.qth.net] On Behalf Of James Bennett
> Sent: Thursday, June 04, 2015 12:33 PM
> To: Elecraft Reflector Reflector
> Subject: [Elecraft] OT: Ferrite Identification Question
> 
> A bit off-thread, but sorta related, as these things ARE used for antennas with my K3/KX3!! I have a bunch of ferrites - donuts, clamp-ons, beads, etc. that I’m trying to identify the mix. With the guidance of Tom/W8JI I’ve fig
> ured out how to use my AIM-4170C analyzer to show at what frequency these things have an R=X value with Q=1. However, I’ve not been successful relating that frequency data to the mix number. An email to Fair Rite has gone unanswered, and trying to wade through their web site is mind-boggling. Does anyone on this list have a URL that points to this information?
> 
> Thanks, Jim / W6JHB
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