Lesson 024 , Band Module for 20 Meters - Continued
This lesson continues with the MP20 20 meter band module.
Use the latest schematic!
Wind 4 yellow toroids. L102, L103, L104, L107. These are 14:2 turns. Mount L107 as shown in the lower right corner. Connect one end of the 2 turn winding directly to one of the ISA fingers and the other end to ground.
Install C127, the vari-cap and C126 150pF. Connect C123 as shown. Install L104 and C122
and C121. These are on the left of L107.
Install Q102 MRF901/911 as shown. Bend the leads down at 90 degree angles. Connect the collector to the open end of L104.
Connect R105 220 and C108 100nF to the middle pin (Emitter) of Q102) These components stand vertical.
Connect a 470 ohm resistor R108 from the base to ground. Connect the 680 ohm R109 from the base to R110/C117.
Connect a 100nF cap C113 to the base of Q102.
Mount and connect L102,C114,C110,C112,C111,C115 and L113. Connect L113 to C113. Connect D100 free end to the free end of L102.
Mount R107, the 500 ohm pot as shown. Ground the right lead of the pot.
Solder C109 100nF from the center pin of the pot to the base of Q103.
Connect R104 10k to the remaining pin on the pot. Connect the free end of R104 to R102 3k3.
Ground the free end of R102. Connect the emitter of Q100 to ground and then base
to the junction of R104/R102 as in picture #13. Bend the collector lead to the left.
Connect the emitter of Q101 to the junction of the pot and R104. Connect the collector to C106, and the other end of C106 to ground.
Connect R103 from C106 to the base of Q103. Connect R101 to C106. Connect the other end of R101 to C107 and
the free end of C1-7 to ground. Run a jumper from C107 to C132. Connect the base of Q101 to the collector of Q100. Connect R100 1k5
from the the base to the collector of Q101. See picture. Connect C105 100nF to the base of Q100.
Build L100 and L101. Mount as shown in the pictures. Connect C100, C101, C103, C104 and C102. Wire as shown in schematic
and the pictures. Connect a piece of RG-174 fro L101 to then ISA CARD finger #39
That is it for the 20 meter band module.
The other band modules are duplicates for the 20 meter module. Only differences are the
tuned circuits. These will be published later (when I get time)
NEXT LESSON - Hookup, calibration and tuning.