Lesson 019 , Transceiver Construction - Mixer POST AMP

This lesson covers the mixer post amp for the MP20.
A very easy lesson dedicated to those doing their 1st UGLY construction.



Solder a 10 nF cap to the free end of R38. Solder R40 (470) from the free
end of C35 to ground in a vertical position. Prep Q7 (2N3866) by placing some
double stick tape to the top the the transistor, and trimming the excess.
Tack Q7 as shown in the picture so that the base of Q7 is very near the
junction of C35 & R40. (Brian uses hot glue for tacking)

Solder a 3 ohm resistor (R42) to the emitter of Q7. Connect C39 (100nF) and
R44 (51) from the free end of R42 to ground. Follow the example in the picture.

Connect C38 a 100nF cap to the collector of Q7. Solder in the PI attentuator
resistors R45, 43 and 46 as shown in the picture.

Prep L7 the thick black toroid with 9 or 10 turns evenly spaced. Strip and Tin
the wire ends.  Use sticky tape and mount L7 as in the pix.

Connect one end of L7 to the collector of Q7.
Connect a 100 nF (C47) cap from the other end of L7 to ground.
Solder a 1k resistor R41 from the base of Q7 to the junction of L7/C47.

PS: This transistor will get hot.  It can handle it - no worries.

This completes the POST amp.

END OF LESSON #019

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