[TowerTalk] Ferrites 31 vs. 77 material

[Bob Shohet, KQ2M]

Hi Jim,

Thank you for your reply and the link to your extremely comprehensive documentation!  I read though it at length today and there was much that I did not understand very well.  I am going to read it again over the weekend.

You mention that the bead only works at VHF but I did not recall seeing anything addressing that.   Is it that the choking resistance is not great enough or is there some other reason(s)?  Could you please explain? 

Tnx & 73

Bob  KQ2M


From: Jim Brown 
Sent: Wednesday, November 06, 2019 10:52 PM
To: towertalk at contesting.com 
Subject: Re: [TowerTalk] Ferrites 31 vs. 77 material

On 11/6/2019 6:28 PM, Bob Shohet, KQ2M wrote:
> I prefer to use large ferrite beads that fit on the coax – roughly 1/2” ID -  1” OD  x 1 1/4” height and then tape the beads in place in physical proximity  to each other next to the feedpoint.

You may prefer that, but that sort of bead only works at VHF. My 
detailed recommendations are here. http://k9yc.com/2018Cookbook.pdf

Yes, #31 material is the weapon of choice for 160M - 6M.

73, Jim K9YC