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Re: [TowerTalk] Fwd: Elementary feedline loss question

To: towertalk@contesting.com
Subject: Re: [TowerTalk] Fwd: Elementary feedline loss question
From: Patrick Greenlee <patrick_g@windstream.net>
Date: Thu, 10 Apr 2014 07:34:03 -0500
List-post: <towertalk@contesting.com">mailto:towertalk@contesting.com>

Just about everyone using a tower in Ham radio also uses ferrites, often on the coax to/from the tower. OK hi-tek guys what is a good experimental lash-up for testing ferrites? Typically the mix is not labeled on the part and how do you know it is labeled right if it is? A lot of kinds and sizes of ferrites available at all kinds of prices typically not labeled. Even if you get what you pay for then a few months later when they are mixed with some previous ferrite bargains which is which?

I don't think identifying the mix is an important goal although you may be able to make an educated guess after measuring performance attributes of your ferrites. What would be good to know and would constitute success would be to get a measure of their characteristics at various frequencies. The preferred method of testing should not require a bunch of lab gear not typically found in a modest shack. A minimal set of gear would include your station's primary equipment, such things as your transmitter, coax jumpers, dummy load,SWR meter, volt meter and watt meter. The test may require putting a toroid on a length of coax and then installing a connector (maybe repetitively.) Tests may require winding an insulated conductor around/through a ferrite core.

Perhaps an antenna analyzer would be available for a different test schema. Maybe there are other pieces of equipment that would be useful and likely to be available. To be accessible to more hams the tests should not be limited to only those requiring more sophisticated gear such as my HP 8753D Network Analyzer with accompanying HP 85041 S parameter accessory for testing from 300 Hz to 3 GHz.


How about it guys? What about a quick and dirty GOOD ENOUGH test to select ferrites based on their in-shack measured performance?

Patrick NJ5G

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