The Commando Shortwave Transmitter by Dave Martin
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THE COMMANDO 20 WATT SHORTWAVE TRANSMITTER
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The "Commando" is the higher power,
high level modulated version of the "Corsair".
Below is the circuit for the basic 48M version.
The table below it gives the changes that are needed for other bands.Below that is the series modulator.
Use when mains power is available.
Below that is the Bridge Modulator circuit using a transformer.This is for 12V portable use.
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The Transformer, AL21219 above, is from a PYE Westminister W15AM PMR set. It may be available from "Garex" . As an alternative you may construct your own using a small transformer such as mains to 12v 1amp.Remove all the original winding and wind the primary with 80 turns of 24 SWG enamelled wire, this will be the audio side that connects to the TDA2003's pin 4's. The secondary winding is 180 turns of 22 SWG enamelled wire, this is the side that gives the modulated VDC.
For larger view,click on picture.

BAND

L6

Turns

L7

Turns

Core

type

C13

pF

C14

pF

C15

pF

C16

pF

3.9MHz

10

21

T-50-2

870

2400

720

  720    

6.2MHz

7

14

T-50-2

560

1500

470

470

7.4MHz

5

12

T-50-2

465

1277

470

470

9.3MHz

4

9

T-50-2

370

1020

300

300