User Manual

Exhibit 6 page 10 of 16
It is advisable to adjust amplifier tuning when antennas have been changed, snow has fallen, new objects
are in the near field of the antenna, etc. Such changes may affect antenna impedance.
NOTE
If you use more than one antenna on a band, the proper antenna must be selected prior to performing the
tuning procedure outlined below.
CAUTION
To avoid damage not covered under warranty, do not switch the BAND switch knob while transmitting. As
discussed above, hot switching will damage the amplifier’s band switch!
CAUTION
Also, never apply drive longer than one minute continuously without pausing for at least one minute to allow
the tubes to cool.
It is recommended that for initial tuning a frequency in the middle of the band be used. First, with no
transceiver power applied, select the band. Then use Table 4-1 to achieve an approximate preset for both
TUNE and LOAD capacitor knob settings :
Band LOAD TUNE
MHz Knob Dial Knob Dial
1.800 - 2.000 47 - 71 54 - 32
3.500 - 4.000 34 - 56 51 - 33
7.000 - 7.300 32 - 39 36 - 30
10.100 - 10.150 62 - 63 50 - 48
14.000 - 14.350 37 - 41 38 - 31
18.068 - 18.168 41 - 43 50 - 48
21.000 - 21.450 59 - 62 16 - 10
24.890 - 24.990 50 - 52 49 - 46
28.000 - 29.700 63 - 69 23 - 10
Table 4-1. Approximate tuning preset
b) Tuning Procedure.
(1) Once the antenna and band have been selected (and the TUNE and LOAD adjustments have been
initially set as indicated in Table 4-1), apply between 10 and 20 W of continuous (key down CW) signal.
(2) Look at the upper LED bar-graph (FORWARD POWER) and adjust the TUNE (right hand) capacitor for
maximum indication.
(3) Watch the TRI indicator above the LOAD (left hand) capacitor and turn the LOAD capacitor in the
indicated direction to center the green LED indicator light.
(4) Increase the drive power to get the desired nominal output; then repeat steps (2) and (3), always
peaking output with the TUNE adjustment.
NOTE
No light on the TRI indicator means that the tuning is too far off. To correct this, turn the LOAD and TUNE
knobs around the table-suggested positions until the TRI indicator illuminates.
no light: tuning is far left: tuning is far right: marker inside: LOAD is tuned:
use TUNE knob turn LOAD knob turn LOAD knob turn LOAD knob turn TUNE knob
for max. Power to the right to get to the left to get slightly left to peak Forward
to get any marker the inside markers inside markers to center it Power
Fig. 4-1. Using TRI tuning aid