Bird Technologies 8320 - Manual (Page 22)

sion. Also, occasionally check the coolant level in the radia-
tor tank.
Preventive Maintenance
If there are signs of coolant leakage around the clamping
bands, try tightening them. If the leakage persists, it is
likely that the O-Ring seal is damaged or deteriorated. Re-
place it; see the sections for “coolant and seals” under Dis-
assembly. Wipe the cooling fins clean of accumulated dust
and lint in order to preserve their efficiency in the transfer-
ring heat to the environment. If any portions of the radiator
have become corroded or rusted, clean the areas with a fine
flint sandpaper, and then touch them up with grey enamel.
RF Assembly Tests
Accurate measurement of the dc resistance between the in-
put to ground, output to ground, and input to output will
provide a good check of the condition of the attenuator. For
these measurements, a resistance bridge, or ohmmeter with
an accuracy of one percent or better at 50 ohms should be
used. Use low resistance leads, preferably a short piece of 50
ohm cable (RG-8A/U or RG-9B/U) with attached Male plugs
which mate with the Female connectors on the attenuator.
When the resistance of the equipment is check at room tem-
perature, the measured readings should be with ± 2 ohms of
their nominal resistance values, commonly 93.7 ohms input
to output and 50 ohms from either end to ground. It is rec-
ommended that for reference purposes, these resistance val-
ues should be measured and recorded upon receipt of the
attenuator and then checked periodically thereafter.
Disassembly
There are no special techniques required for the repair or
replacement of components in these Tenuline Attenuators.
A screwdriver and possibly an adjustable wrench are the
only tools needed. The paragraphs below outline the compo-
nent removal procedures.
RF Connector The connectors are a “Quick-Change” design which permits
easy interchange with the use of only a screwdriver. This
process does not interfere with the essential coaxial continu-
ity of the attenuator RF input, output or the coolant oil
seals. For replacement, proceed as follows:
1. Remove the four 8-32 x 5/16 round head machine
screws from the corners of the RF connector.
Bird Model 8320S Tenuline Attenuator
12