- 5 -
Install 3 glass diodes D5 – D7
(1N4148). Direction is important. For
each diode, bend the lead nearest the
black stripe 180 degrees at the end of
the glass so that both leads are parallel
and 0.1 inch apart. Install vertically on
the board such that the bent lead (on
the stripe side) goes to the hole
nearest the left edge of the PCB. See
the image to the right.
Install transistor Q1 (2N2222A), which
provides Push-To-Talk (PTT) for the
radio transmitter. Be sure to orient flat
side to match the flat side shown on
the silk-screen pattern. The middle
lead will need to be bent back slightly
to align with the hole.
Install the 18-pin IC socket for U1. Be
sure to align the notched end of the
socket with the marked end on the silk
screen. First solder just two diagonally
opposite pins of the socket, and check
that the socket sits flat on the PCB.
Then solder the remaining socket pins.
Do not insert the chip into the socket at
this time.
Install potentiometer R6, (10K, 103)
which adjusts audio output level. Make
sure the short middle lead pokes
through the hole enough to be
soldered.
Install potentiometer R9, (10K, 103)
which adjusts carrier detect sensitivity.
Install resistors R1 (8.2K gry-red-red),
R2 (3.9K, org-wht-red), R3 (2K, red-
blk-red), R4 (1K, brn-blk-red), & R5
(220K, red-red-yel) which create the 4–
bit digital to analog resistor ladder.
Bend like the diodes. Direction does
not matter.
Install resistors R7 and R14 (10K, brn-
blk-org).
Install resistors R10 – R13 (1K, brn-
blk-red). These limit the current
flowing into LEDs D1 – D4.
Install resistor R8. (2.2K, red-red-red)
which is used for PTT on some radios.
If TinyTrak3Plus will be used with a
radio that does not key via current
through the mic line, R8 can be easily
cut out of circuit later by cliping the
resistor at the top of the bend and
pulling the leads apart slightly.
