AN/ARC-5 Handbook

							 
Figure 4-5. Circuit Test Point Diagram  
						

							4--12. TRANSMITTER AND MODULATOR. 
 
4--13. DYNAMOTOR UNIT. 
 
4--14. PRELIMINARY INSTRUCTIONS: All tests on the transmitter will be performed using the 
AN/GRM-1 Test Setup optional wiring, illustrated in Figure 1--3, or the AN/ARC-5 Test Bench 
Harness. Select transmitter one or two, corresponding to the desired units position in the test rack. 
(See figure 4--15.) 
 
STEP TEST 
POINT TEST 
EQUIPMENT 
CONTROLS NORMAL INDICATION POSSIBLE 
CAUSES OF 
ABNORMAL 
INDICATION 1. F Emission selector 
switch to CW. 
TRANS. POWER 
switch to ON. 
Switch on TS-58 
set to position 1. Filaments light; relays 
K-5O, K-53, and K-54 
energized; dynamotor 
runs. TS-58 meter 
indicates 54 (27 volts). Fuses F-50 and F-5I 
blown; defective 
coils on relays; dirty 
or corroded 
contacts; defective 
dynamotor. 2. G Switch on TS-58 
set to position 3. 
Key the 
transmitter. TS-58 meter reads 51-
55 (510-550 volts d-c.) Defective relay K-52; 
defective dynamotor 
windings; shorted C-
55; shorted 
components in 550-
volt circuit; defective 
plugs and jacks on 
equipment.  
						

							Figure 4-6. Circuit Test Points  
Figure 4-7. Converter Circuit Test Points  
						

							Figure 4-8. Converter Circuit Test Points  
Figure 4-9. Antenna Circuit Test Diagram  
Figure 4-10. Antenna Circuit Test Points  
Figure 4-11. Typical Transmitter, Top View, Shield Removed  
						

							4--15. OSCILLATOR.  
 
(Follow chart below.) 
STEP 
TEST 
POINT TEST 
EQUIPMENT 
CONTROLS NORMAL 
INDICATION POSSIBLE 
CAUSES OF 
ABNORMAL 
INDICATION 1.  
 Emission selector 
switch to CW. Set 
VTVM on 120-volt 
d-c scale, --polarity 
and connect to 
TEST  
POINT H, the 
ungrounded 
terminal of PA grid 
resistor, R-74 and 
chassis. TRANS. 
POWER switch to 
ON. depress the 
Microphone 
button. See figure 
4--17. VTVM should indicate -
40 to -70 volts d-c grid 
bias, if oscillator is 
supplying proper 
excitation to PA grid 
circuit.  Defective oscillator 
tube or circuit 
components 
defective relay K-53; 
defective PA tubes; 
open R-74; low 
voltage on oscillator. 2. 
  Set switch on TS-
58 to position 4. 
Depress the 
Microphone 
button.  TS-58 meter should 
read 32-46 (16 to 23  
ma. oscillator plate 
current.)  Same as above; 
oscillator not 
oscillating; open R-
68, shorted C-58A. 3. 
  Tune transmitter 
FREQUENCY  
dial to calibrator 
crystal frequency. 
Depress the 
Microphone 
button. Maximum shadow angle 
on the Magic  
Eye tube screen as the 
FREQUENCY  
dial is rotated to the 
crystal frequency.  Same as above; 
defective Magic 
Eye tube; defective 
crystal; no or low 
voltages.  
						

							 
Figure 4-12. Typical Transmitter, Bottom View  
Figure 4-13. Modulator, Type MD-7/ARC-5, Bottom View  
						

							 
Figure 4-14. Typical MD-7/ARC-5 Modulator  
Figure 4-15. Transmitter and Modulator Test Points  
						

							 
Figure 4-16. Diagram