Technalogix TAUD-40, Manual

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I-3
Operating Safeguards
It is a known fact that our broadcast transmitters and translators enjoy 50-ohm load impedances. So much
so, that it is imperative you maintain 50-ohm impedances throughout your system. In return, your equipment
will provide you with maximum power transfer to the antenna and decreased reflected power heading back
towards the amplifier pallets, reducing the amount of magic smoke that gets let out of the power amplifier.
Before anything is turned on, ensure that there is a 50-ohm path from the output of each stage to the input
of the next, all the way to the antenna.
In addition to maintaining proper 50-ohm impedances throughout the signal chain, it is also important,
whenever possible, to make sure the RF drive going to the input of the power amplifier is removed before
turning on or turning off the DC power supply. This is because all of the RF transistors used in the individual
amplifier pallets are fabricated with LDMOS (Laterally Diffused Metal Oxide Semiconductor) technology.
Nice and linear yes, but they do not like to make any RF power when their supply voltages are not within a
specific range. When you first turn your power amplifier on or off, the DC power supply’s output voltage may
take a while to stable out to a safe operating voltage. Ten seconds wait before applying the RF drive will
ensure no issues arise.
Our power amplifiers are designed to reliably generate a specific RF output power. Failing to adhere to
overdriven amplifier warnings can decrease the reliability of your system, and frankly, makes our repair
department busy and grumpy. If you need to transmit to a little larger coverage, you are better off increasing
antenna gain, and more importantly, antenna height above average terrain. On TV and FM broadcast
frequencies, insufficient antenna height puts an upper limit on your range, regardless of power levels, as the
distance from your antenna to the radio horizon is limited.