1 shows the schematic. Third grid of both tubes is grounded.
Second grids of the both tubes are connected to 250-V voltage
1 2xGU50 PA
The PA was designed for CB-station for 27-MHz. It is
defined the input circuit that provides good matching at the band.
The PA is made on the base of 2xGU50 PA. Output power of the 3xGU50 PA is 180- 200 Wtts.
The PA was designed for 160, 80, 40 and 20 meters. Input circuit
is broadband and can match the PA in wide frequencies range. The
input circuit is described at Antentop-
1-2008, p.62. Figure 2
shows the schematic of the 3xGU50
2 3xGU50 PA
At practical design it was found that capacity of the
high-voltage capacitor at matching circuit is changed a little
inside the working band. It allows to me to change the hard-to-
find capacitor for available for me constant capacitors. The capacitors
are switched with help of a usual ceramic switch.
P.S. My thanks to Sergey Mironov
for the help during design, manufacturing and tuning of the PA.