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Re: [TowerTalk] [Bulk] Cutting a FT-240 type 33...in half

To: towertalk@contesting.com
Subject: Re: [TowerTalk] [Bulk] Cutting a FT-240 type 33...in half
From: "Roger (K8RI) on TT" <K8RI-on-TowerTalk@tm.net>
Date: Thu, 12 Feb 2015 12:48:41 -0500
List-post: <towertalk@contesting.com">mailto:towertalk@contesting.com>
Sounds more like you inductively coupled the RF to the cores using them as a load, rather than as an in line chole

73

Roger (K8RI)


On 2/10/2015 5:36 PM, Steve Hunt wrote:
Jim,

That is such a revolutionary statement that I felt I must investigate it. So I loosely wound 4 turns of PTFE wire on a Type 43 toroid - the wire was barely touching the toroid. The impedance measured around 200 Ohms at 10MHz - almost entirely resistive. I connected it across my tuner, adjusted for a good match, and then applied 20W at 10MHz for 5 minutes.

At the end of 5 minutes I touched the wire and then the toroid. The wire was barely warm, but I scolded my finger on the toroid!

There's no doubt at all that the dissipation mechanism is within the ferrite toroid, not the wire; if the wire gets hot it's because it's in contact with the toroid.

Or perhaps I completely misunderstood what you are claiming?

Steve G3TXQ



On 10/02/2015 21:18, Jim Brown wrote:
There is dissipation in a ferrite core choke in the resistance coupled from the ferrite core. It is the coax shield that gets hot, not the ferrite (although the heat in the coax may be transferred to the ferrite material).


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