The G2DAF HF amplifier !

If you want to build an amplifier using a tetrode but don't want to mess around with  screen and grid powersupplies this one is for you!
HV and filament voltage required, just as in a grounded grid amplifier. Screen voltage is derived from the input RF and the grid is at DC ground.
Check the circuit description below.

                                     The HF station, amplifier rack to the right                                     The QBL 5-3500 tube

                                   Top of the rack is a small homebrew 4CX350A amp for 144 MHz, below that is my homebrew HF amp described below.

Check some detailed pictures, circuit diagram and tube specs

Anode compartment Anode plus tank circuit switchable 160-10 mtrs
Anode compartment 1 Anode plus tank circuit, side panel view
Anode compartment 2 Anode plus tank circuit, top view
Bottom view Input circuit, relay pwr supply, screen bypass
Screen bypass 1 Screen (g2) PTFE sandwich bypass, close view
Input Input PI-network, relays switch different bands
Input 1 Input PI-network plus input resistors
Schematic diagram  G2DAF style QBL 5-3500 schematic diagram
Input circuit, coils Schematic of input circuit using 9mm dia coils with trimmer cores
T/R switching T/R switching using RJ-1A relays
QBL 5-3500 specification sheet PDF with all tube data. (1Mb)
Check out SM3PXO and SM3BDZ (SK) spectrum analyzer measurements of a G2DAF amplifier


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