The SM2CEW EME amplifier for 144 MHz

The pictures below show my 144 MHz EME amplifier using the QBL 5-3500. The original two-part article that describes the anode stripline can be found in December 1973 and January 1974 QST. The amplifier described in that article uses an 8877 tube and is also featured in the ARRL Handbook as "A 2kW PEP amplifier for 144 MHz". The input line and the screen bypass shown here is designed specifically for the QBL tube. Specifications for the QBL 5-3500 tube (PDF-format)

QBL 3-3500 normal operating parameters:
Anode 5000V @ 1.5A
Heater 6.3V @ 32 A
g1 -107V @ 40mA
g2 +800V @ 80mA
Anode 1 Anode side, stripline with flappers and bypass capacitor
Anode 2 Anode different view, HV rfc to PTFE sandwich bypass capacitor
Anode 3 Another view,  flapper arrangement
Anode 4 Anode, close view, neutralizing probe = 1mm dia wire, visible in the low right hand corner
Input 1 Input circuit, stripline with serial butterfly capacitor plus capacitor to ground 
Input 2 Input capacitor, note the serial capacitor is butterfly with only stators connected on each side for very low series capacitance. Also note neutralizing probe, the 1 mm dia wire that protrudes into anode compartement.
Input 3 Bias feed arrangement, RFC, serial resistora and bypass.Bias tap is on input line.
Screen bypass 1 + input Screen bypass, sandwich PTFE/brass capacitor with single side PC-board on top for added capacitance.
Screen bypass 2 + input Another view. Also note filament transformer
Bottom view Bottom view, filament transformer, output line, screen loading resistors
Front panel Front panel of QBL 5-3500 amp for 144 MHz. All tuning, input/output accessable from front panel.
Driver amplifier 4CX250B coaxial anode line amp

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