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Re: Topband: Choke Construction Info Needed

To: "DAVID CUTHBERT" <telegrapher9@gmail.com>
Subject: Re: Topband: Choke Construction Info Needed
From: "Tom W8JI" <w8ji@w8ji.com>
Reply-to: Tom W8JI <w8ji@w8ji.com>
Date: Thu, 26 Jul 2012 18:01:29 -0400
List-post: <topband@contesting.com">mailto:topband@contesting.com>
> That is only 226 Ohms at 1.8MHz and at 1500W will be dissipating about 30W 
> in a 50 Ohm system but Phil didnt say how he is feeding his tower which is 
> resonant well below 160M.

That choke is probably too small and will change SWR, but thankfully 
reactance in reactances does not dissipate power. Reactance simply stores 
and returns energy.

226 ohms of resistance would be about 330 watts of heat at 1500 watts into 
50 ohms (about 273 volts RMS).


To find the heat, we would need to know inductor Q. If Q was 1, it would be 
330 watts.
A pure reactance is zero heat. Odds are the inductor Q would be in the 
hundreds, so dissipation would be negligible.

73 Tom 

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