Make your own free website on Tripod.com
PARTS  LIST  FOR  TRANSVERTER



Resistors are 1/4 watt carbon comp (ohms) and capacitors are ceramic unless
otherwise noted.

R1, R3, R10, R12, R18, R20: 100 ohms
R2: 68
R4: 50 ohms, 6 watts (3 150 ohm 2 watt carbon comp in parallel).
R5, R9, R13: 1000
R6: 51
R7: 10K
R8: 220K
R11, R15, R17: 100K
R14, R16**: 220
R19: 10K audio taper pot, 1/4 inch shaft.
R21: screwdriver trimpot accessible from outside case.
R22, R27: 330
R23, R28: 6.8
R24, R29: 2.2
R25: 4.0
R26: 1200
R30: 680
C1, C8: 8-50 pF ceramic trimmer.
C2: 30 pF NPO
C3: 22 uF
C4, C5: .012 uF
C7: 3 pF (may be needed for reliable oscillator starting).
C6, C9, C12, C13**: 1 uF 25V tantalum
C10: 270 pF
C11: .01 uF
C14, C15, C16, C18, C19, C20, C22, C24, C26: 0.1 uF monolithic.
C17, C21: 100 uF 16V low ESR electrolytic.
C23, C25: 10 uF 25V tantalum.
D1-D9, D10-D13, D15, D17: IN914/IN4148 silicon switching diode.
D14: Green LED
D16 Red LED
D18: 1N4001 power diode.
F1: 3.5 amp Raychem Polyfuse (Digikey).
J1, J2: BNC female chassis connector.
L1: 1uH ferrite shielded (commercial).
L2: 67uH  "      "   "       "
L3: 2.2uH on 1/2 inch powdered iron torroid (tap at 5 turns +/-) *
L4: ~40 ohms total winding Z at 185 KHz (Center Tapped)(Hi-u torroid) *
Mixer: Minicircuits SBL-1MH high level diode ring DBM
Q1: 2N2222A NPN
Q2: MPS6531 or ECG/NTE 123AP high freq silicon NPN
RL1, RL2: DPDT, Omron G5V-2-H1 (12V, 960 Ohm coils)
S1: Mine are wired to the on/off switches on the TRC-485 CB's I use.
T1: Winding impedances 7x ckt Z (but 10x should be OK)(Hi-u torroid or Amidon 1811-77 pot core).
Turns ratio 1:7 *
T2: Winding impedances 10x ckt Z. (Amidon 1811-77 pot core) Turns ratio 1:7. Try ~60 turns #26 for 50 ohm secondary). *
U1: LM833 (National specalized audio preamp BJT op-amp)
U2, U3: TDA2003 or ECG/NTE 1288
X1: 26.920 (CB CH 37 Rcve with 455 KHz IF)($2.50 ea at Radio Shack 1-800-843-74225)
 Other channels can be used.
Case: Cast Aluminum Hammond 1197 (119 x 93 x 34mm)
* I used junk-box cores for L3, L4, T1, T2. L3 should be Hi-Q and use a core to confine the fields for self-shielding  Q is not very important for L4 and the transformers, but tight coupling between windings is required (ie no air gaps). Good luck.
** R16 and C13 were added to stabilize the preamp at maximum gain with the input open circuit.


HOME