Yet another episode in my search for toroid cores

For Field Day, a friend and I made couple of C-Pole antennas as described in the April 2004 issue of QST. One disadvantage of this antenna is that it requires a balun to operate properly. We decided to make these baluns, but finding the toroid cores was a real hassle. We got lucky, though. I found one at a local radio shop, and my friend just happened to have one in his junk box.

The antennas worked pretty well, and now I want to make a few more, meaning that I need to find more of these cores. The other day, I got the bright idea to check the Mouser website to see if they stock them. Well, they list a bunch of Fair-Rite toroid cores online, but they don’t seem to actually stock any.

I then surf over to the the Fair-Rite website. I request their catalog online and it arrives a couple days by UPS even though I note that I’m just an amateur radio operator. It’s a very cool catalog, except that I can’t figure out how to find an equivalent Fair-Rite part for the Amidon FT-240-61. Specifically, I can’t figure out what material each of the toroids is made out of.

So, I call them this morning, and ask for an applications engineer. I get a very cheery guy, who when I explain my problem, just chuckles. “Yes,” he says, “that’s one problem with our catalog.” Then, he goes on to explain how the material number is actually the third and fourth digits of the part number.

When I say to him that I am trying to figure out what Fair Rite part is equivalent to an Amidon FT-240-61, he chuckles again. He says that Amidon actually buys these parts from Fair Rite and puts their part number on them. When all is said and done, I figure out that the Fair Rite part number for the Amidon FT-240-61 is 5961003801.

So, I go back to the Mouser website. They list this part, but of course, they don’t have any in stock. They will order it for you, but you have to order 100 of them at $5.52 each. Deciding that I don’t want to spend $552, I decide to look elsewhere.

I type “5961003801″ into Google and get back only five responses, one of them being the Fair Rite website. This doesn’t look promising, but I click on the link to www.hobid.com. Apparently, this is a site that brokers surplus electronics components. They do list the 5961003801, and note that sellers registered with HOBid.Com have 5,532 of them somewhere. I typed in a request for 20 of them with a target price of $3 each.

An hour later, I get a reply from a company named United General Computer Inc. They offer to sell me the parts for $9.34 each. That’s a reasonable price for new parts, but the impression I get is that these are surplus, so I’m inclined not to buy them. It’s now 4 pm and I haven’t received any other offers, so maybe this company is the only one that had any. We’ll see.

Comments

  1. you can get them at http://www.amidoncorp.com/ for 9 bucks a pop plus shipping. Try http://www.oselectronics.com/ at $8.75 each plus shipping. I’ve used them both a couple of times, seemed reliable.

  2. Dan KB6NU says:

    Back when I wrote this, I ended up finding one of these at a local electronics shop. I was quite amazed that they’d have one, and it was the only one they had.

    I have since found another source. Alltronics (www.alltronics.com) has the Amidon AB-240-125 Antenna Balun Kit for $9.00. This kit includes the FT-240-61 core plus enough 14 ga. magnet wire to build a balun. I just bought a couple of these kits to try to build a 4:1 balun.

    They also have the Amidon AB-200-10 Antenna Balun Kit for only $5.50. This kit has a T-200-2 core, which is not as beefy as the FT-240-61. Another drawback is that the SWR of a balun built with this core will probably not be quite as flat as a balun using an FT-240-61. All things considered, it’s probably worth paying the extra $3.50.

    73, Dan

  3. I have no local electronics shop. Nearest one is in Morgantown, WV about 90 miles away. I have to wait for hamfests in Frederick, or Hagerstown, MD 80 and 100 miles away. Thank goodness for Mouser and Digi-Key.

    In as much as ferrite mix 61 and powdered iron mix 2 have hugely different permeabilities and frequency characteristics, I’m not surprised that baluns wound on those two cores would respond differently over a wide range of frequencies.

    None-the-less, I appreciate your frustration trying to buy toroidal cores. I needed smaller cores for BCB oscillators, BCB RF amps, and IF amps. It was a couple of hours on the web before I was able to locate anything more than “Buy this bag of 5 unmarked cores.” Cheap, but no cigar. Now, to find a place that sells a few cores and DP3T vertical slide switches so I can avoid two shipping charges. Oh, well.

  4. What is the difference between the Amidon FT-240-61 and T-200-2 cores? I plan to build a broad band UN UN

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