In Case Of Trouble
1. Lowest SWR out-of-band:
If all minimum-SWR points trend above or below
the desired band allocations, you may adjust it by changing the wire length.
Shorten to increase frequency and lengthen to lower frequency. For all MFJ-1982
models, be sure to make any length adjustments
at the far end of the wire
to
avoid changing the spacing between the compensating coil and the matching
network.
2. Abrupt SWR changes while transmitting:
If the matching transformer core is
allowed to overheat and reach Curie temperature, the toroid permeability will
change abruptly and create a severe mismatch. In most cases, when the core
cools, normal operation will be restored. However,
take this event as a warning to
reduce transmitter power or shorten the duration of your transmissions. Also,
repeated overheating can permanently alter the permeability of the matching
transformer core, rendering it unusable.
Important Warning: If you experience a sudden change in SWR,
stop
transmitting immediately
and allow the matching transformer to cool for at
least 30 minutes. Then, adjust your operating power or transmission time
accordingly!
3. "RF in the Shack":
If you use a longer feed line (more than 10 or 15 feet),
ground the matching network
and
your station equipment separately. Also, where
possible, run feed line along the ground rather than suspended above it.
