144 MHz GS35 Amplifier

Technical Characteristics

Ouput Power ....................... 2KW
Power Gain ......................... 13dB
Anode Voltage ................... 4500V
Anode Current ...................... 1A
Grid Voltage ........................... 42V
Grid Current ..................... 300mA
Drive ..................................... 100W
Harmonic attenuation > 55 dB


SCHEMATIC

mides bracket support

469 360 371 367

363 368 361 364

20010c 20014c 20021c 20025c

365 196 198 222 356



Material List

CONDENSERS
Mica C1 = 5000 pF 500V
Variable C2 = 25 pF 250V
C3, C4, C5 = 1000 pF 600v, (feedthrough by-pass)
C6 = 1000pF, 7500V, DOORKNOB
C7, C8 = 100pF, 15KV, DOORKNOB
"C9" not used
(**) C10 = 40pF

(**)Capacitor "sandwich" made of two metallic plates separated by teflon sheet, 4mm thick.
The fixed plate of 80 x 70 mm, connected to the two coils, supported by a piece of bar of teflon that isolates it from the chassis and maintains mechanical rigidity.
The tilted plate (fig.2) of 95 x 85 mm, is subject to the chassis by a brass hinge. In order to move the plate a rod threaded "pusher" is used (fig.1) a laminate of beryllium copper (fig.3 and fig.4) held to the base of the bar of teflon acts mechanically opposite to the push of the rod and helps provide an optimal electrical connection from the movable plate of C10 to chassis ground (fig.6).

C10 construction

cargol.jpg fig2.jpg fig3.jpg
fig4.jpg fig7.jpg fig6.jpg
Imagen6.jpg Imagen4.jpg

The holes in the metallic plates are due to use of recycled material, coming from taking apart.

GS35B CLAMPS
The clamp that holds to the GS35b and the one of connection of the anode is of aluminum or brass of 10mm of thickness; see the photos for its implementation.
The chimney of the valve is teflon, 110 x 100 mm.

COILS
L1, L2 = 4 turns of 1mm silverplated wire, coil diameter = 16mm, lgt = 20mm.
L3 = Z-144 RF choke.
L4 = 11 bifilar turns of 2.5mm enameled wires, coil diameter = 16mm
L5 = 8 turns of 1mm enameled wire, coil diameter = 16mm, lgt = 30mm
L6 = (*) 1.5 turns of 3/8" copper tubing, coil diameter = 45mm., lgt = 35mm
L7 = 4 turns of 1/4" copper tubing, coil diameter = 40mm, lgt = 50mm.
L8 = 20 turns of 1mm enameled wire, coil diameter = 10mm, lgt = 20mm

(*) See pictures, below
- For the adjustable part of L6, a silverplated brass hoop 6.25mm wide and 45mm inner diameter is used; the original came from surplus homemade material.
- The dimentions are not absolutely critical and any hoop of similar dimensions can be used.
- The hoop is insulated from the chassis by an axis of insulating material (plastic, delrin or similar) and meeting of teflón.

20013.jpg 20015.jpg 20017.jpg 20015a.jpg 20014.jpg

PLATE CONTROL and POLARIZATION
Instead of using the classic circuits of polarization and measurement I have used TRIODE BOARD of RF PARTS but also take a look at:
Barend Hendriksen of Holland.
The coaxial relays from UR4LL
Triode Board in RFPARTS or DOWN EAST MICROWAVE.
 
If you do not find some material or you need information you can get in contact with me,

Quim, EAÁXV
mailto:ea3axv@terra.es

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