Bird Technologies 8890-400 Series - Manuale (Pagina 33)

s Inspect the cooling fins for accumulation of
dust and lint. Also, check the painted metal
parts for signs of corrosion.
Preventive Maintenance
The main factor in maintenance is care and cleanliness. The
element socket should be kept plugged as much as possible
to prevent dust intrusion. If a plug-in element is to be used
for this purpose, use the highest power element available.
The element should be positioned so that the arrow is point-
ing midway between the forward and reflected measuring
positions. This will not only protect the meter but will also
avoid exposing the element diode to dangerous potentials if
the RF line section should be energized.
If there are signs of coolant leakage around the clamping
band, try tightening it. If the leakage persists, it is likely
that the O-Ring seal is damaged or deteriorated. Replace it,
refer to the Disassembly paragraph. Wipe the cooling fins
clean of accumulated dust and lint.
Contact Adjustment
When cleaning the socket bore, be careful not to disturb the
spring finger of the dc contact. It is important that the oper-
ating position of the part be maintained. If the spring finger
of the dc contact requires adjustment. It may be done manu-
ally. The tip must be positioned far enough out to maintain
good contact with the element, but not so far as to interfere
with easy entry of the element body. To adjust follow the in-
structions below.
1. Remove the two screws which fasten the dc
jack, with attached spring finger, to the side of
the RF line section.
2. Lift off the jack assembly carefully to avoid los-
ing the small teflon insulating bead. The bead
straddles the base of the phosphor bronze
spring and nests in the counterbore on the side
of the RF body.
3. Gently push the spring finger in the direction
necessary.
4. Replace the assembly. When replacing the as-
sembly, be sure that the bead is again properly
positioned.
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Maintenance