Topband: Checking antenna analyzer calibration

Tom Rauch w8ji at
Fri Sep 29 14:01:56 EDT 2006


Sorry for the delay. After having an operation my up time is 
very limited.

> Putting known values of capacitors, inductors and 
> resistors in series or
> parallel combinations across the input would give one a 
> specific impedances
> that could be calculated and compared with the MFJ 
> measurement. When I
> started this thread I was hoping that the very clever W8JI 
> had some really
> elegant [read simple & accurate] method for finding out if 
> the instrument is
> reading correctly or needs repair. So far he has been 
> silent which I take to
> mean he is busy on other things or he doesn't have my 
> desired "quick fix".

To rough check the 259 or 269 you can use a capacitor with 
very short leads as well as some resistive loads.

Resistors are actually good enough if you have something as 
low as 12.5 ohms and as high as 200 ohms. I use surface 
mount resistors soldered right across from the center pin to 
the shell of a connector.

Your advice on short leads and known capacitors is good 
advice. I would limit lead length to one inch or less. I use 
1% tolerance silver mica caps. The analyzer has a mode where 
it reads capacitance directly. If that reading is on, any 
reactance reading will be on. So save yourself some work and 
just directly read the capacitance. The capacitance is 
already calculated from the "X " detection.

There is a section on my website

Step six tells you how to get into the calibration mode. It 
might take a little practice to rock into the calibrate 
(test) mode. You can look directly at the compensated 
detector voltage in that mode.

73 Tom 

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