Re: [IRCA] coax loss

[Rick Kunath <k9ao@xxxxxxxxxxx>]

Patrick Martin wrote:
> Thanks Chris. I have always been a nit-picker when it comes to my
> antennas and coax. I try to squeeze every 1 millionth DB out of them. I
> guess I go overboard as some have said. It seems I am always out there
> trying to make improvements on everything. Probably 99% of the time,
> there is no difference.

I generally test any suspect cables with an Anritsu time-domain 
reflectometer, but most folks won't have access to a piece of test 
equipment this expensive.

I also have one of these:

http://www.mfjenterprises.com/products.php?prodid=MFJ-269

and find it a very handy piece of test gear to have. Whether you'd get 
enough use out of it to justify purchasing one of these or just be 
better off putting the cash into new coax you'd have to decide.

An ohm meter will tell you only one part of the picture, i.e. ohmic 
losses in the center conductor and shield. And as was mentioned up the 
thread, since you are testing using DC, you don't get the same 
skin-effect as you would using an RF test signal. You can't measure 
dielectric losses, overall loss at a particular frequency, impedance, or 
velocity factor.

But it sure would tell you if you had serious corrosion and very high 
resistive losses.

Rick Kunath
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