Quote:
Originally Posted by KA5S
Elsewhere in the Forums an Amateur asks how to combine two 300 watt 2m amplifiers. The answer is the Wilkinson Hybrid. This page, while labelled 6m, is a excellent tutorial how to build one. And it only needs some 70 ohm coax and VHF-capable 100 ohm resistors.
Cortland
KA5S |
Quote:
Originally Posted by VK6ZGO
Make sure both Amplifiers are quite close in output power level,as any
unbalanced power is used to make those 100 ohm resistors hot!
73 VK6ZGO
|
My current gig is with the largest OEM of sealed CO2 lasers, where we drive them with RF power. The laser tubes are about 10% efficient and produce up to about 250W of laser power. Our RF drivers then, have to produce kilowatts of RF and often use Wilkinson combiners. If, in a two-driver system, one driver stops working, the resistor has to 'suck up' half the other driver's power. The resistor is sized to do this. There are various manufacturers of flange-mount RF resistors up to about 800W. They can be found at the
RF Cafe.
In a previous life in FM broadcast, we had two 8kw transmitters combined, for 16kw to the antenna. The hybrid was an impressive setup! One night, in the dead of Winter, a screen bypass capacitor in the socket of one of the driver tubes shorted, effectively shutting-down that unit.
When we arrived to the unheated shack, it was
very warm inside. And, the reject load (an air-cooled 4kw unit) was working hard!
vy 73,
Bryan WA7PRC
We appreciate your support.
Combining VHF Amplifiers
Linear Mode
