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300w 23cm Amplifier

Published in QST magazine (December 2004). Also see ARRL web files.

The 23 cm amplifier pictured here delivers more than 300 watts with 10 watts drive. I've actually driven it to 400w+. It's water-cooled, thermally stable, and very smooth-tuning. It includes a TR switch, relay sequencer, and all controls necessary to operate the amplifier safely and reliably.

click any of the thumbnails below for enlargements or explanations

The Completed Amplifier The Performance Test The modified GS-15B Tetrode Why Water Cooling?
completedamp.jpg (101140 bytes) pwrmeter.jpg (64616 bytes) thetube.jpg (6331 bytes) watercooler.jpg (26271 bytes)

At it's heart is a Russian tetrode, the GS-15B, modified for water cooling. It runs in a well-made cavity I purchased from Mats Bengtsson, KD5FZX.  Complete information on the cavity itself can be viewed here, courtesy of Mats and Paul Goble, ND2X.

Featured below are construction details on the complete amplifier and power supply I built for this cavity. Click here for the complete schematics.

Simplified Schematic Power Supply 101 +28 and +12 volt supplies Bias and Metering
simpleschematic.jpg (44314 bytes) ps-1.jpg (22066 bytes) lvps.jpg (24773 bytes)
 
Relay Sequencer Mounting the Cavity Coolant Connector Parts RF Relays
coolantparts.jpg (34495 bytes) relays.jpg (23228 bytes)
 
Some Other Parts PCB Mounting Cavity and 2nd Fan Mount Ventilation
meterswitch.jpg (26904 bytes) pcbmount.jpg (52393 bytes) cavandfan.jpg (49456 bytes) ventholes.jpg (51759 bytes)
 
RF Cabling PCB Wiring PCB Component Side Wiring View (top)
rfcables.jpg (35557 bytes)
 
Another Top View HV and Disconnects Other Disconnects Rear Panel Lettering
cavitydisconnects.jpg (73961 bytes) moredisconnects.jpg (56272 bytes) rearpanel.jpg (76696 bytes)
 
Power Supply Tuneup