SWR-584C Instruction Manual
HF/VHF/220MHz SWR Analyzer
26
•
Voltage at the center of the resonance becomes high, causing severe arcing.
•
Current in the windings becomes very high, resulting in severe heating.
To test for self-resonance:
[ ] Install and test the choke in its normal operating location to incorporate stray capacitance.
[ ] Disconnect any choke leads leading to associated circuitry.
[ ] Connect the analyzer to both ends of the choke using a short 50-Ohm jumper.
[ ] Set the analyzer for its default
R&X
function in the
Basic
menu.
[ ] Tune the
VFO
to slowly sweep the choke's target operating range (specific band, etc).
[ ] Looking for impedance dips. These identify series-resonant frequencies.
When a low-impedance dip is detected, move a small insulated screwdriver blade along the
choke windings to find a point where the series-resonate impedance changes suddenly. This
jump identifies the location where the voltage peaks, and it's the spot where adding or
subtracting even a tiny amount of capacitance will have the greatest effect. To shift the
resonance off the critical frequency (or out of the band), try removing turns to reduce
capacitance -- or add a capacitive stub. Note that even a small change in capacitance has a
much more impact than making a small change in inductance because the L to C ratio is very
high.
8.0 Technical Assistance
If you have any problem with your SWR-584C, first check the appropriate section of this
manual. If the manual does not reference your problem and the problem isn't solved by reading
the manual, you may call
VECTRONICS Technical Service
at
662-323-5800
. We can serve
you best if you have your unit, manual, and all pertinent information about your difficulty handy
so you can answer questions the technicians may ask.
You can also send questions by mail to VECTRONICS, 300 Industrial Park Road, Starkville,
MS 39759; by FAX to 662-323-6551; or by e-mail to [email protected]. Send a
complete description of your problem, an explanation of exactly how you are using your unit,
and a complete description of your station.
