QRO Technologies HF-2500DX Instruction Manual page 15

18.10*
21.30
24.90*
28.50
*Transceiver's Tuner Used
A Word About Wattmeters: The most reliable and accurate Wattmeters are either the Bird or
Coaxial Dynamics thru feed. Wattmeters which use a ferrite core for r.f. sampling can be
unreliable at high power levels. If you are using such a wattmeter and you observe an output level
less than 1,500 watts for the values listed above, your wattmeter is probably not giving you an
accurate reading.
Input SWR: The input SWR for 160 & 80 meters will be less than 1.5 :1. The input SWR for 40
meters should be around 1.5 :1 to 1.6 :1. Input SWR for, 20, 15, and 10 meters is at the most
1.5:1. These input SWR conditions should present no problem due to the lower drive power
requirements of this amplifiier. If you prefer a lower input SWR, use your transceiver's tuner to
adjust for a better match.
WARC Band Operation: The HF-2500DX will operate on the WARC bands. You may need to
use the transceivers internal tuner to provide a low input SWR on these bands. Use the following
band positions: 17 Meters use 15 Meter position, 12 Meters use 10 Meter position. Once you
have a low SWR reading using your transceiver's tuner, proceed with the tune up procedure
outlined above.
SSB OPERATION: Some transceivers RF output (carrier level) control DOES NOT control
the output power during SSB operation. If you have one of these transceivers and you go
to SSB operation after initial the initial tune up procedure, your voice peaks may cause
the screen grid current to go past full scale causing the amplifier to go into the fault state.
You will have adjust your microphone gain or speech processor so the screen current and
power output levels are within the specified levels. The ALC control can facilitate this
procedure. It is normal to see some negative indication of screen current during SSB
operation.
USING THE FRONT PANEL ALC CONTROL TO ADJUST
You may want to utilize an alternative to adjusting the drive power at the transceiver. The Front
Panel ALC Adjustment Control allows you to adjust the ALC for the amount of output power you
desire. Using this procedure, you would set the ALC Control to minimum (fully counter-clockwise).
Tune the amplifier for maximum output. Then advance the ALC Control (clockwise) for the amount
of output power you want. The ALC circuit of the amplifier supplies negative feedback voltage
to the transceiver which reduces the amount of drive coming into the amplifier. Only use this
AMPLIFIER OUTPUT POWER.
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