Shortwave Broadcast Amplifier
This is what a 30 kW PEP SSB/ISB, 8 kW AM carrier SW broadcast amplifier
I fabricated all metal here, including welding the cabinet frame. The
Anode to plate-tuning capacitor lead must be short, low inductance, and the
Components around the tube are the minimum safe distance to
The return from the vacuum plate tuning cap to the socket is through the wide
Screws are 3-inch spacing where only shielding HF signals, and less than 1.5
One area with high ground currents is under the plate tuning vacuum
Note the plate choke is well-spaced from any metal, and is very slender and
Tuned input is driven by a belt drive. Note the switch shaft does not extend
Tank frequency range is 3-22 MHz.
PA tube is a 3CX15,000A7 Eimac.
The output relay is a 30 ampere Jennings vacuum relay.
Teflon 1/2 inch semi-rigid cable goes down through the chassis to the 7/8th
The black cable to the rear is the bypass cable.
7/8th EIA flange connector for output.
The air pressure switch is just below the tube with orange wires. This switch much close to
Bottom of RF section. This RF tight box encloses the input tuning networks
This is a temporary test transformer and rectifier.
Actual running supply is three-phase.
The low profile cabinet has wheels recessed below the bottom plate. The frame
Input relay is a Jennings RJ1A.