Re: HALF INCH 12.7MM IN DIAMETER FERRITE RODS.
This is Gary DeBock, ferrite rod transplant enthusiast on the west coast of the USA. Welcome to the group site, and to the worldwide Ultralight DX Team.
As you may have suspected, half-inch diameter ferrite rods are no longer in production, and the only way to obtain them is to purchase old vintage portable radios from eBay or other sources, and remove the rods for your projects. This is not an ideal situation, but currently it is the only possible supply source.
If you need a high-quality half-inch diameter ferrite rod that is a full 7.25 inch length, may I suggest the Heathkit GR-17 and GR-24 portables, which occasionally show up on eBay, going for around $25 US. Old Heathkit AM-FM stereo tuners from the 60's (AJ-33, etc.) also have half inch diameter rods, with lengths around 6.25".
The procurement of 3/8 inch rods is much easier, and an experimenter in the USA can usually track down all he needs in short order. Sony vintage radios (6R-33, TR-6400, ICF-S5W, etc.) all have a 3/8" by 6.25" rod of high quality, and other vintage radios by Panasonic and Sanyo also have similar rods. These radios (with the exception of the ICF-S5W) are extremely cheap on eBay, and go for around $10-20 on average. Most of them are inoperable, which makes the tinkerer feel a little better when he takes out the ferrite rod :>)
There will shortly be an article written concerning my 7", 14" and 20" ferrite-bar transplant experiments in the Sony SRF-39FP ultralight radio, which have resulted in ultra-sensitive DX machines. I hope this detailed article will help those who have interest in this fascinating experimentation.
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