HAMTRONICS r304, Installation Operation & Maintenance, Page: 7 / 10

©1998 Hamtronics, Inc.; Hilton NY; USA. All rights reserved. Hamtronics is a registered trademark. Revised: 4/2/03 - Page 7 -
trimmer cap C6 can also short to the
ground plane and require such spac-
ing away from the board.
Table 4. Typical Test Point Voltages
TP1 Tuning V. Normally set at +4Vdc
TP2 Buffer
approx. +5Vdc
TP3 Sig. Level With SQUELCH control
fully ccw, varies from -0.5
Vdc with no to +0.85 Vdc
full quieting.
TP4 Freq. Varies with frequency of
input signal. Voltage at
this point normally is ad-
justed for +3.3Vdc with a
signal exactly on fre-
quency. Can vary a little
without being a problem.
Table 5. Typical Xstr DC Voltages
Xstr Stage E(S) B(
G1) C(D) G2
Q1 vco 1.0 1.5 7 -
Q2 doubler 0 0.65 5.2 -
Q3 buffer 0 0.65 4.6 -
Q4 dc filter 7.0 7.6 7.8 -
Q6 RF ampl 0 0 8 4
Q7 Mixer 0.5 0 8 2.6
Q8 5V regulator 5 5.6 8 -
Q9 sq. open 0 0 8 -
sq. closed 0 0.65 0.1 -
Table 6. Typical IC DC Voltages
U1-1 4 U1-2 4
U2-1 2.1
U2-10 2.5
U2-2 5V locked U2-11 2.5
(2.5V unlocked) U2-12 5
U2-3 8 * U2-13 3 *
U2-4 8 * U2-14 5
U2-5 8 U2-15 *
U2-6 0-8 (4V tuned) U2-16 *
U2-7 0 U2-17 5
U2-8 4.8 U2-18 0
U2-9 5 * U2-19 0
* = pin not used U2-20 2.3
U4-1: 8
U4-10: 0.75
U4-2: 7.5 U4-11: 1.4
U4-3: 7.6 U4-12: 0.55 (with
U4-4: 8 sq. just closed)
U4-5: 7.6 U4-13:
U4-6: 7.6 0V (sq. open),
U4-7: 7.6 7.6V (sq. closed)
U4-8: 8 U4-14: 0
U4-9: 3.3 (Varies U4-15: 0
w/ freq.) U4-16: 1.8
U5-1: 0
U5-5: 0
U5-2: 0 U5-6: 6
U5-3: 0 U5-7: 13.6
U5-4: 0 U5-8: 7
Table 7. Typical Audio Voltages
Audio Test Point Normal Level
U4-9 (Discriminator) 3V p-p audio
E4 (Disc Output) 2V p-p audio
TP-6 1V p-p audio
E1 (Repeater Output) 1V p-p audio
U4-11, top of R27 2.5V p-p noise
(noise ampl output)
Top of Vol Cont R32
300mV p-p audio
U5-2 (af ampl input) 0 to 100mV p-p
(depends on
volume control)
U5-6 or E2 0 to 8V p-p audio
(speaker ampl output)
Figure 1. Placement of U2
Under PC Board (dot is pin 1).