Inductor
106 nano- H
contains 4 turns. ID is 10 mm. Inductor is wound by wire in diameter
of 1.5- mm (14 AWG), 5- mm gap between turns.
Inductor
62 nano-H contains 2 turns. ID is 10
mm. Inductor is wound by wire in diameter of 1.5- mm (14 AWG),
5- mm gap between turns.
Filter
has SWR 1.1:1 at the 2- meter band. Figure 12 shows
SWR for the filter at the 2- meter Band. Figure 13 shows
return loss of the Low Pass Filter
for 145- MHz Band at frequencies 200- 500- MHz.
Figure 14 shows
attenuation for the Low Pass Filter
for 145- MHz Band at the 2- meter Band.
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Best
result for tuning the filter will provide a Spectrum Analyzer.
In this case the tuning may take just 20 minutes. At first step
the filter is tuned for low SWR. At this step inductors are adjusted
by pressing/ stretching.
At the second step the filter is reversed (where was the filter's
input- now is the filter's output) and the filter checked and
adjusted if it is needed. The filter may be tuned without a Spectrum
Analyzer. Just turn on the filter to a transmitter, load the filter
to 50- Ohm, and tune the inductors to minima SWR. The procedure
may be done with the real antenna system (cable plus antenna).
73!
RL1L
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