[TowerTalk] 40M rotary dipole

[Grant Saviers]

Newark or Mouser often have ok prices for the "FT-240-31" large toroid 
core.  Chris KF7P.com has had them on sale at times.  I've bought from 
all three.

http://www.newark.com/fair-rite/2631803802/ferrite-core-cylindrical-119ohm/dp/43K4703?ost=2631803802&iscrfnonsku=false&ddkey=http%3Aen-US%2FElement14_US%2Fsearch

http://www.mouser.com/ProductDetail/Fair-Rite/2631803802/?qs=%2fha2pyFadujg9vFABS5CZWkClXV4tmC2yGMdLN2jsic%3d

An interesting trade-off is the price performance of the "big clamp on" 
vs a stack of the FT-240-31's.  There is a lot of ferrite in the clamp 
on and it is very convenient for existing cables but needs securely 
closed tight with tie wraps or Scotch 33 for good performance.

A 1/2" wide cloth/glass tape is very handy to tie the FT-240-31 stacks 
together before winding the coax.  RG142 TFE coax can be wound fairly 
tight on a stack and easily handles QRO power.

Grant KZ1W

On 9/20/2017 7:31 AM, Dave Sublette wrote:
> Thanks for all the suggestions on the RF choke.  I read the article by K9YC and concluded that the best approach wold be to wind RG8X around 6 Fair-Rite toroids made from type 31 material and 2.4 inches in diameter.  The big problem is they are listed at over $17 each from the distributors.  I will need 18 of them eventually.  6 each for this dipole and two more yagis.  That’s a large price tag, but still cheaper (and better performing) than the commercial units available, according to K9YC.
>
> I have (again at the suggestion in the paper by K9YC) sent a request for quit to Fair-Rite, asking what quantity I would have to buy in order to get “a decent price”.  It might work out that I could make a large purchase and offer kits of toroids to the group.  I’m not looking to make money.  I only want to have a good choke at the lowest price I can find.
>
> I may put the antenna up with a temporary choke on it and replace it when/if I can get the toroids.
>
> I will keep you informed as to what I find.
>
> I appreciate your inputs on this project.  It’s been fun.
>
> Dave, K4TO
>
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