[TowerTalk] Fwd: Elementary feedline loss question

[Patrick Greenlee]

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