Ramsey Electronics HR40 User Manual
Page 11
HR40
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11
RECEIVER ASSEMBLY:
1. Install the RCA antenna jack, J1. Solder all four points.
2. Install C5, a .01µF ceramic disc signal coupling capacitor. This
capacitor brings the signal up to the front of the PC board. Notice the long
PC trace from J1 through C5 to R1
3. Install potentiometer R1, the RF gain control. Insert it into the PC
board so that it seats firmly and is straight and even. Solder the three pins
and the two mounting tabs.
4. Install L1(marked 421F-123), which tunes or preselects the signal
input from the antenna through C5 and R1
5. Install U1, the SA602 IC mixer-oscillator. The marked end of the IC
(band or dot) must face the FRONT of the PC board. If you wish, install an
8-pin DIP socket, still remembering to orient and install the SA602
correctly. Please don't be afraid to solder U1 directly to the board as we
have seen more repair problems with DIP sockets than from direct
soldering of IC chips.
The parts that we have put in so far bring the signal from the antenna jack up
to the RF Gain control (actually the RF attenuator) and to a tuned circuit
composed of L1 and its internal capacitor. Inductor L1 allows us to match and
tune the 40 meter band signals to the SA602’s input.
6. Install C6, .01µF (marked 103, .01, 10nF). This capacitor bypasses
pin 2 of the SA602 to ground. Bypass means to provide a nice low
impedance (impedance means AC resistance) path to ground.
7. Install R4, 270 ohms (red-violet-brown), which drops the 9 volt battery
supply to 6-7 volts, safe for the SA602.
8. Install D2, 6.2 volt Zener diode. This is the smaller of the two diodes
and has a painted glass body. This diode acts as a voltage regulator by
keeping the voltage across it constant.
9. Install C10, a 100-220µF electrolytic capacitor. Electrolytic capacitors
are marked by polarity and must be installed in the proper direction. You’ll
see that one side of the capacitor has a black band and is marked with a ‘-
’ sign, this is the negative side, the other side is the positive lead. Make
sure you insert the positive lead into the ‘+’ marked hole on the PC board.
10. Install C11, a 100-220µF electrolytic capacitor. Remember to observe
correct polarity. C10 and C11 provide voltage stabilizing which directly
improves the performance of the SA602 oscillator.
11. Install C2, 100pF ceramic disc capacitor (marked 100 or 101). This