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| EME
PA 432 MHz |
Open
part of PA where is cavity with tube |
| Original G1 - G2
power supply replaced by GM3SEK power supply boards |
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TH 293 datasheet |
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| Existing stabilizer of G1 and
G2 was replaced by GM3SEK tetrods
boards. Toroidal transformers made by Czech republic company JK
Eltra according request 580V / 50mA AC G2 and 150V / 10mA AC G1.
Transformer for heating 5,8V/50A AC. |
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| Feed trough
capacitors for heating lines. Due to connection with cathode is necessary
build capacitors as showing here. Blue weirs are lambda/4 long lines 16mm2
flat. BCB capacitor has 157pf and extensions capacitors are 470pF/1kV
ceramics. This solution protect very well PA for oscillating and leaking
RF trough heating transformer and cathode power supply |
| Mechanical
parts of PA 432 MHz - rebuild Plish cavity |
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| Front
panel - left down small power supply including G1 - G2 GM3SEK boards, left
top measuring SWR - HF and Ua, Ug1 and Ug2. Measuring below left Ia, Ig1
and Ig2. Right cavity with TH347. Box top left including also control
board, where are switching relays. There is also Kathrein
directional coupler and board with LED diodes for indication. Schematics
you can find in section Electric parts |
Rear
panel |
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| Left side
- Ug1 - Ug2 power supply down. |
Right
side, blower and heater transformer 5,8V/35A |
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Electrical parts |
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GM3SEK tetrods
boards
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Block diagram - connection between HV
PS and GM3SEK G1-G2 PS
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Internal connection between GM3SEK
boards and led and control boards
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Connection between Led diodes and
control boards trough 25 pin connector
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Heating of TH 347 - 327 - 293 is
requiring 30 second heating with half of value, in this case I have
installed transformer with two primary coils and time delay switching relay
with thermistor 2A/250V in primary coil.
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PCB of LED diodes board
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Schematic
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PCB of Control board
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Schematic |
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PCB of HV divider board
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Schematic |
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PCB of G1 and G2 divider board
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Schematic |