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1. GENERAL
RF deck of this amplifier is built in aluminium compartment wich must be
electrically tight to avoid RF radiation. RF radiation will decrase output power
and can cause self oscillation of the transmitter chain as well as a health risk.
We can built in normal19" "box" version the line ME3000..
2. INPUT CIRCUIT
Tube is driven in grid 1 with grounded catode. Grid 1 is loaded with 200 ohm RF
power resistor in order to decrease gain end increase stability factor. Loading
resistor is connected on the "way" between grid 1 and resonance tuning
capacitor of the matching circuit due to this parasitic inductance of the tube
plus tube socket. The input circuit is working between 144-146 MHz without
extarnal tuning. The input SWR is better than 1:1.5 in this segment.
3. OUTPUT CIRCUIT
Output resonator is based on W6PO design. Tuning for resonance should be
done by changing length of two resonators rather than increasing C5 tuning
capacitor. The output capacitor value is about 3-4 pF.
Tune is very easy to maximum output .
4. COOLING
Cold air inlet is located in to input conpartment. We can deliver the PA with
internal or external fan.
Air flows trought over the catode box and across the tube body and anode
cooling fins. Hot air outlet is located above the tube anode cooling fins. The
protection circuit will work over 75 degr air temperature.
5. TUNING THE AMPLIFIER
Tuning the input resonance circuit should be done using VSWR meter
connected between driver and input. Output coupling capacitor should be set as
on the schematic to about 4pF.
Output you can indicate across the built in power meter. /FWD knob in/ The
output is 3KW in right end of the meter. /10x scale/ All was made by the factory /
Before any high voltage will applied to the tube, tube should be run on heater for
several hours especially if the tube wasn't use for long time. From this point of
time, cooling must be operational.
Having heater voltage connected to the tube without adequate cooling will
damage the tube.
3.0 TECHNICAL DESCRIPTION
5
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