Vectronics VC-300D - Manual (Page 7)

VC-300D Digital Bargraph Antenna Tuner Owner's Manual
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9. Read the SWR on the red scale at the point where the two needles intersect. Repeat
step 8 until the lowest SWR reading is obtained. The SWR should be 2:1 or lower.
Note: This procedure takes patience the first time. The transmitter and antenna controls
vary the capacitors and provide fine adjustments. The inductor control provides
course adjustment.
If the SWR cannot be reduced to the lowest reading try increasing or decreasing
the reading of the transmitter control. Then try to null the antenna control for the
lowest reading. You may want to try reversing this procedure by increasing or
decreasing the antenna control and nulling the transmitter control. Always
perform these adjustments at low power.
10. When you have tuned your antenna to the best SWR, record the settings of the
TRANSMITTER, ANTENNA, and INDUCTANCE controls on the previous chart for
future reference. When you retune, use these settings as your starting point.
NOTES
1. An SWR or 1:1 is best, but an SWR as high as 2:1 may be acceptable. Check you
transmitter manual for details.
2. If you cannot get an acceptable SWR, lengthen or shorten you antenna and/or
feedlines and retune.
3. If you get low SWR readings at more than one setting, use the setting that:
••••
Gives the highest FORWARD power reading.
••••
Gives the lowest REFLECTED power reading.
••••
Uses the largest capacitance (highest number) on the TRANSMITTER and
ANTENNA controls.
4. Any time a new or different antenna is connected, it is necessary to repeat the tuning
procedure for each antenna.
USING THE BARGRAPH
1. Plug in the AC adapter provided with your tuner into jack located on the back panel.
2. In the Tuning Section, after completing the the-up sequence, key your transmitter
through the tuner into the dummy load. Adjust for a meter reading of 100 Watts
Forward (at this time the SWR will have been adjusted for minimum value as
outlined in the Tuning Section).
3. Rotating the LEVEL control activates the bargraph and the segments will illuminate
progressively as the LEVEL control is increased. If your cross-needle meter is
reading 100 Watts as indicated in (2) rotate LEVEL control so that the last LED (red)
illuminates. This signifies that the 100 Watt average single tone reading on the