Safety Interlock Switch; Driving Power; Tube Precaution - QRO Technologies HF-2500DX Instruction Manual

RF OUT Connect this socket to the cable coming from your antenna.
Note: Use shielded cable, such as audio-type cable, for the following connections.
KEY XMT Connect this socket to the T/R relay socket on your transceiver. This connector
requires contacts that are normally open in the receive mode and closed in the transmit mode.
This contact sinks 12 VDC to ground at 80 mA.
+15 V XMT If your transceiver has a provision for +15 VDC on transmit for keying external
devices, such as linear amplifiers, connect this socket to the appropriate socket on your
transceiver.
Note: If your transceiver has neither of the above keying methods, you will have to use some
other means. For instance, you could use a shorted RCA phono plug by placing it in the Key XMT
socket. Then, you would have to manually turn off and on the Operate/Standby switch located on
the front panel.
ALC OUTPUT Connect this socket to the ALC input of your transceiver. A 0 to 20 V negative ALC
voltage is present at this socket. Refer to your transceiver manual for proper connection
information. Whenever the Amplifier is overdriven, the ALC circuitry creates a negative voltage
that is fed back to the transceiver to reduce its gain and help prevent "flat-topping".Protective
circuitry of this nature is a valuable circuit element, but it is not a substitute for proper adjustment
of the transceiver drive.

SAFETY INTERLOCK SWITCH

While the Amplifier's top cover is in place, the interlock switch closes to allow AC line
voltage to reach the power transformer. When the top cover is removed, the interlock
switch opens and disconnects the line voltage. This does not discharge the bank of power
supply filter capacitors. Be sure to allow the filter capacitors to discharge before you
touch anything inside the Amplifier. You can select the High Voltage function of the
Multimeter to check the high voltage potential.

DRIVING POWER

This Amplifier is designed to operate at full ratings when it is driven by a transceiver that has
approximately 50 watts of RF output. If you use a transceiver that delivers more than 50 watts,
carefully adjust the driving power to avoid "overdrive" and the creation of spurious signals, which
create needless interference to other operators.
IMPORTANT: In no case should you advance the power output control of your transceiver
beyond the point where the Amplifier's power output ceases to increase. If you turn the control
past this point , nonlinear operation may occur.

TUBE PRECAUTION

After prolonged operation, let the Amplifier run for several minutes without drive applied so the
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