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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 build normal 19'' "box" version the line ME2000-V.
2. INPUT CIRCUIT
Tube is driven in catode over T filter. The input resistance of tube is about 40
Ohm.
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
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 degree 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.
Next anode voltage should be applied /from your external high voltage supply
ME 3000-S/ and idle conditions of the amplifier checked. Push the PTT and you
can see about 100mA on left meter. When you have more than this value, you
can adjust for this value with P7 poti on Zener PCB. /On case you use home
brew HV supply with lower or larger Ua voltage than 3500V. /Max Ua 3.6KV! /
3.0 TECHNICAL DESCRIPTION
5
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