Comments on: Yet another episode in my search for toroid cores http://kb6nu.com/OLD403/ My personal adventures in amateur radio Wed, 07 Jan 2009 04:26:35 +0000 http://wordpress.org/?v=2.6.2 By: Rag http://kb6nu.com/OLD403/#comment-298653 Rag Mon, 07 Apr 2008 17:21:12 +0000 #comment-298653 What is the difference between the Amidon FT-240-61 and T-200-2 cores? I plan to build a broad band UN UN What is the difference between the Amidon FT-240-61 and T-200-2 cores? I plan to build a broad band UN UN

]]> By: Charles Toth http://kb6nu.com/OLD403/#comment-43954 Charles Toth Sat, 21 Oct 2006 20:43:47 +0000 #comment-43954 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. 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.

]]> By: Dan KB6NU http://kb6nu.com/OLD403/#comment-43786 Dan KB6NU Mon, 16 Oct 2006 11:47:42 +0000 #comment-43786 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 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

]]> By: Charles Toth http://kb6nu.com/OLD403/#comment-43765 Charles Toth Sun, 15 Oct 2006 19:40:10 +0000 #comment-43765 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. 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.

]]>