13
N O T E
If you use more than one antenna per band, it is necessary that you select the proper
antenna BEFORE the next step. Retune after selecting a different antenna for the
same band, since both impedances may differ substantially (unless their VSWR is
excellent, i.e. below 1.2:1 for both).
C A U T I O N
Do not switch the BAND switch knob while transmitting with the amplifier! Hot
switching (while transmitting) will eventually destroy the band switch, not covered
by the warranty!
C A U T I O N
When tuning, do not apply continuous drive longer than 3 minutes and after that
pause 1-2 minutes for tube cooling.
We recommend that you tune-up at the center frequencies of the preferred frequency band. First
select the band switch (never with RF applied!). Then use table 4-1 in order to achieve an approximate
preset for both TUNE capacitor and LOAD capacitor knobs:
zHM,dnaBlaiDbonKenuTlaiDbonKdaoL
2-8.105-5754-57
4-5.3 03-05 06-77
3.7-704-3466-37
2.01-1.01 01-21 03-23
53.41-4154-5542-62
2.81-81 36-16 25-45
54.12-1271-4433-53
52-9.42 18-97 94-74
7.92-8202-6423-63
45-05 51-04 21-61
Table 4-1. Approximate tuning preset
b) Selecting the plate-load True Resistance Indicator (TRI) tuning aid.
You may select TRI scale in three different ways:
- By pressing simultaneously for a moment the PREV+NEXT buttons. This will insert a 6dB attenuator
between the driver and the amplifiers input (the ATT LED will light), so youll not need to reduce the
drive power during tuning. Press PREV+NEXT buttons momentarily again to switch the attenuator off
the input and to return to the old screen. If you use any of PREV or NEXT buttons only, the attenuator
would be switched off too, but the information screen would change to respectively previous or next.
- By pressing repeatedly either PREV or NEXT button (whichever is nearest), until you reach the TRI
scale. This will not insert the attenuator, so youll have to use less than 20W drive (unless the amplifier
is nearly correctly tuned), otherwise the next step would be executed automatically:
- By simply applying a normal working (50-60W) drive power, while the amplifier is not yet tuned.
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