24
Troubleshooting
Erratic VSWR
If VSWR readings flucutate, then either there is residual water in the
system, or system components are damaged.
Follow this sequence of actions:
a. Repeat the purging process as described in
Purging the System
on
page 16.
b. Test impedance again.
c. If purging does not correct the situation, you may have liquid water
in your transmission line. Use a vacuum pump to dry the transmis-
sion line. [A vacuum pump can be rented or borrowed from a refrig-
eration contractor.]
d. Hold as much vacuum as you can for 24 hours, then check VSWR
again.
e. If VSWR is still erratic, contact Shively Labs.
Change in Coverage
Changes in broadcast coverage may be caused by the same factors
that produce VSWR changes. If coverage seems to have changed, look
for VSWR changes and troubleshoot in accordance with
High VSWR at
Startup or during Operation
on page 23.
It is important to recognize, however, that apparent changes in cover-
age may be due to subjective factors or faults of the receiving equip-
ment. Before doing more than checking the VSWR, be sure that an
actual coverage change has occurred.
Pressure Loss or
Excessive Gas
Usage
If your system will not hold pressure as described in
Leak Testing
on
page 14, look for the cause in
Table 6
.
Paint has been applied to the radia-
tors, possibly during a recent tower
painting.
Remove the paint from the radi-
ators.
Table 5. Troubleshooting High VSWR (continued)
Possible Causes:
Cures:
Table 6. Troubleshooting Pressure Loss or Excessive Gas Usage
Possible Causes:
Cures:
O-ring missing or poorly installed
in transmission line, feedline, or
baymount flange.
Find the leaky O-ring using soap
solution. Replace the O-ring.
Loose connecting hardware be-
tween components.
Tighten loose connections when
found.
