RF compression becomes apparent. As you monitor the RF output and
simultaneously increase the drive level, you should see the output rise fairly fast,
with the rate of rise decreasing after you pass some point on the adjustment. This
is the setting where RF compression starts. For best transmitted signal linearity
you should set the drive level just below this start of compression point.
1. You can insert a tone via the microphone jack of your transceiver or use the time-
honored method of saying a long Aaaaaaaaaaaaaah while monitoring the RF
output with a scope, diode detector and voltmeter, or watt meter.
2. Key your transmitter and insert the tone while monitoring the RF output and
slowly adjusting the RF drive pot (R-83) for an increase in output. Identify the
adjustment position where rate of output increase seems to slow. Back the drive
level back down by ½ watt or so. This is your position of best output signal
quality. Unkey your transmitter.
NOTE: Do not keep the transmitter keyed for more than a few seconds with
a tone input. Steady tones exceed the duty cycle designed into the
RF PA amplifiers and their heat sinks, and may overheat the
IRF-510 MOSFETS.
