KB4ZGC on how to make a highly accurate yet inexpensive dummy load and wattmeter capable of showing
MAXIMIZING RF POWER OUTPUT
The simplest way to ensure maximum reasonable power output without component damage is to run the DC voltage in the 13 to 14 volt range, observing a maximum limit of +15VDC. Typically, an automobile power source is 13.6 volts when the engine is running, and most mobile rigs are specified at this voltage level.
IMPORTANT NOTE: If you are experimenting with this transmitter and see a sudden and massive increase in power output and DC current, you have not reached the promised land or created a 100 watt amplifier! Sudden surges like that are a sure sign of amplifier
TROUBLESHOOTING HINTS
The QRP power amplifier is very straight forward and simple to troubleshoot. When beginning to track down a problem, use some common sense to narrow down your search area.
If the amplifier is not keying upon application of RF power, check to see if the T- R relay circuitry is operating. A quick
If the amplifier does not amplify, check to see if RF is flowing through to transformer T2 and across to the RF power transistors. Amplified output should appear at output transformer T1 and then on to the low pass filter. Remember that RF enters and exits through relay contacts on K1.
Do the transistors get too hot? Do they get hot without amplifying? Things to