FX 146
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56
R: RESISTORS (Fixed, Trimmers, and Panel-Mounted)
[ ] [ ] Q5
2SC2498 NPN RF
F8
VCO common base buffer
[ ] [ ] Q6
2N3904 NPN
B9
Carrier detect switch
[ ] [ ] Q7
2SC2498 NPN RF
E9
VCO
[ ] [ ] Q8
SD1127 or MRF237
TX2
Transmit final amplifier
[ ] [ ] Q9
2N3866 NPN RF
TX1
Transmit driver
[ ] [ ] Q10
NE021
TX14
Transmit buffer
[ ] [ ] Q11
2N3904
M18
Grounds mic amp in receive
[ ] [ ] Q12
PNP 2N3906
(228256)
M20
PTT switching
[ ] [ ] Q13
PNP 2N3906
(228256)
M21
+8R PTT output
[ ] [ ] Q14
PNP 2N3906
(228256)
M22
+8T PTT output
[ ] [ ] Q15
2N3904
H10
Offset matrix switching
[ ] [ ] Q16
2SC2498
F15
VCO buffer
[ ] [ ] Q17
2N3904
CR33
Voltage regulator
[ ] [ ] R1
220K
CR29
[ ] [ ] R2
1K
CR27
[ ] [ ] R4
68K
CR4
[ ] [ ] R5
10K
CR3
[ ] [ ] R6
3.3K
CR25
Sets hysteresis for U1
[ ] [ ] R7
100K pot w/switch
A2,B12
Volume
[ ] [ ] R8
47 ohm
CR26
[ ] [ ] R9
270
CR6
[ ] [ ] R10
470
DR26
[ ] [ ] R11
47K
CR2
[ ] [ ] R12
100
DR15
[ ] [ ] R13
100K pot
CR31
Squelch control
[ ] [ ] R14
47K
DR25
[ ] [ ] R15
1K
E16
FX-146
•
91
Install the following resistors, each in upright position:
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DR13: R16, 47K ohm (yellow-violet-orange).
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DR14: R17, 470 ohm (yellow-violet -brown).
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DR15: R12, 100 ohm (brown-black-brown).
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DR16. Install C20, 100 pf. (marked 100 or 101).
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DR17. Install C30, 47 pf (marked 47).
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DR18. Install L5, .015 uH, a small 2 turn wire coil.
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DR19. Install C28, 47 pf (marked 47).
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DR20. Install L2, another .015 uH small 2 turn wire coil.
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DR21. Install L6, yet another 2 turn .015 uH coil.
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DR22. Install C31, 47 pf (marked 47).
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DR23. Install C104, 8.2 pf.
INTERMISSION: Notice how our work is methodically creeping toward all
the FM IC circuitry you did in Stage CR ?
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DR24. Install C22, 100 pf (marked 100 or 101).
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DR25. Install R14, 47K ohm (yellow-violet -orange).
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DR26. Install R10, 470 ohm (yellow-violet-brown).
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DR27a. Select a 2SC2498 NPN RF transistor. This is the first of such
transistors used in this circuit, they are marked with 'C2498' on the flat
side. Again, do not confuse these with the more common 2N3904 (or
similar) transistors such as already installed.
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DR27b. Install Q2, 2SC2498 transistor.
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DR28. Install C17, 100 pf (marked 100 or 101), and all your work in this
stage is now connected to the RF input of U1.
Stage DR Progress Note:
No other testing is required at this point other than to double-check the
accuracy of your parts installations. However, experienced builders will
recognize that VHF signals could now be received very well by connecting
an antenna and tuning a signal generator coupled to U1 provided that the T-
R circuitry is operational. A more useful preliminary receiver test will be
conducted after we complete the VCO stage.