NOTICE
Using a feeder of coaxial cable at SWR > 3:1 on HF, and particularly on the 10- and
6 meters bands, is not recommended. At such high values of SWR, the high voltages,
high currents, and heat associated with line losses, risk to permanently damage your
coaxial cable or antenna switch.
It is highly advisable to re-adjust amplifier tuning when antennas have been changed.
Re-adjust amplifier tuning when you change the band or between CW and SSB segments within the same
band.
Update tuning periodically, even if you have not changed band or antenna, in particular when a significant
change in the environment occurs (snow, ice, newly appeared or removed massive objects, alien wires
nearby etc.) that would cause significant changes in the antenna impedance and an increased SWR .
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 SWR are excellent,
i.e., below 1.2:1 for both).
At SWR above 1.2, retuning is mandatory although the two SWRs might be nearly same,
for example 1.8 and 1.7 for the old and a new antenna. It might happen that one
antenna is 90 Ohms and the other - 30 Ohms, each requiring totally different tuning.
NOTICE
Do not switch the BAND switch knob while tuning or transmitting with the amplifier!
Hot switching will eventually destroy the BAND switch, not covered by the warranty!
NOTICE
When tuning, never apply continuous drive longer than 3 (three) minutes without
pausing at least 1-2 minutes to allow the tube to cool.
It is recommended that for initial tuning a free frequency in the middle of the band be selected (make sure
the frequency is not being used by others so that you do not make QRM).
First, with no transceiver power applied, select the band. Then use Table 4-1 Approximate tuning presets in
order to achieve an approximate preset for both TUNE capacitor and LOAD capacitor knobs settings:
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