Ramsey Electronics FX Series Manual page 74

diode (gray body, black band). Observe correct placement of the banded
cathode end. Zener diodes are widely used as voltage regulators. They
have the interesting property of keeping a constant voltage across their
terminal leads.
CR26. Install Q1, NPN type 2N3904. Before soldering, press the transistor
as far into its holes as possible, with the flat side oriented as shown in the
parts diagram.
CR27. Install C102, 10 uf electrolytic capacitor. Watch your polarity! The
positive side is marked on the PC board and usually the negative side is
marked on the capacitor.
The last 4 steps involved the building of a voltage regulator to supply a
steady source of voltage to the receiver IC chip. At this point in your work, you
could actually receive strong local signals by connecting an antenna wire at
C17 and a high frequency signal source (e.g. a signal generator) to the input
of U1. The signal you would receive would be on a frequency of the signal
generator frequency plus 21.4 MHz. Because we have not yet constructed any
of the input circuitry (Stage DR), you would also hear any signal on the signal
generator frequency minus 21.4 MHz.
PRECAUTION ON WIRING FOR CONTROLS, JACKS, ETC:
The volume control, squelch control, speaker jack and power cord are
installed quite early in the assembly sequence so that tests can be conducted
periodically during assembly.
The disadvantage of this approach is that there is considerable wear or strain
on the various wire connections as the PC board is repeatedly flipped back
and forth during assembly. This is a serious consideration because more
radios and computers malfunction because of broken wires than from
electronic parts going bad. For this very reason, such wiring is ordinarily done
as a final step in electronics assembly.
To minimize damage to the control and jack wiring, use one of the provided
wire cable ties to hold down this group of wires temporarily. Loop the tie
through the PC board mounting hole near U10's position, grouping the wires
snugly to the board. After fully assembling and testing the kit, the tie may be
clipped off, allowing you to once again use the PC board mounting hole.