> side. The calculated Z in question is 402 +j208 @ 28mhz however the
> 259 just shows 405 with J0. Others have said to me the 259 does not
> always show the Jx part when its known to exist.
There are four potential problems.
When load impedance gets very high or low (remember it is
designed to work around 50-ohm systems), the difference between
a reactive load and resistive load is less than the resolution of the
eight bit words. Even a one-bit error (256/1 or 0.4%) can produce a
large change in indicated output impedance at very high or low
impedance loads.
When there is any external voltage (even dc voltage) across the
load it often upsets the detector diode's voltages.
The unit could be miscalibrated.
By rocking between the GATE and MODE buttons a few times a
second at turn on, the unit goes into a "calibrate mode". The bits
for Vz (load voltage), Vr (reflected power voltage), and Vs (voltage
across a 50-ohm resistor in series with the load) are displayed.
With a 50-ohm load, Vs and Vz should both be 127-128 bits, and
the total of the two should be 255 bits.
I'll try to find time someday to outline a calibration procedure on my
web page. It is on my list, when I have time.
73, Tom W8JI
W8JI@contesting.com
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