MFJ-9412 Instruction Manual
12-Meter SSB Transceiver
10
No signals received:
Check antenna and feedline for breaks or shorts. If okay, you
should hear increasd background noise when the antenna is connected.
Spurious signals received:
Look for interference from nearby computers, modems,
TVs, cordless phones, or other devices that may emit 24.9-MHz signals.
Distorted Receiver Audio:
Check for foreign debris in the speaker basket.
Erratic transmit:
Check antenna VSWR. Also, check battery or power supply
voltage. If supply drops below 12-V under load, the radio's regulator will drop out and
operation will become erratic. If you operate exclusively from 12-V batteries, reduce V-
REG output to 10.0V (measured on tab of U9) for added regulator headroom.
High meter deflection on transmit, low RF output:
ALC pot R11 may be set too
high (or VSWR may be high). Adjust R11 for mid-scale deflection into a 50-Ohm load.
Splatter, low meter deflection:
ALC pot R11 may be set too low (or there may be a
feedline short). Adjust for mid-scale deflection when transmitting into a 50-Ohm load.
S-meter does not return to zero:
Confirm that V-REG (R78) is set for 10.5V on tab
of U9. Confirm that AGC threshold (R11) is set for 4.3V at RSSI test point (no signal).
When both readings are set, adjust R17 for zero meter deflection.
Poor carrier suppression:
Turn Mic gain off (fully CCW) and key the radio while
monitoring signal on an external receiver. Adjust R57 for minimum carrier.
Low or distorted transmit audio:
Check to see if mic gain is set too low. Also,
make sure you are using a 600-Ohm low-Z dynamic microphone.
Excessive background noise on signal, hum:
Mic gain set too high for the ambient
noise conditions. Also, is Mic or radio next to a power transformer or electric motor?
TECHNICAL ASSISTANCE
If you have any problem with this unit first check the appropriate section of this manual.
If the manual does not reference your problem or your problem is not solved by reading
the manual, you may call
MFJ Technical Service
at
601-323-0549
or the
MFJ Factory
at
601-323-5869
. You will be best helped if you have your unit, manual and all information
on your station handy so you can answer any questions the technicians may ask.
You can also send questions by mail to MFJ Enterprises, Inc., 300 Industrial Park Road,
Starkville, MS 39759; by Facsimile (FAX) to 601-323-6551; or by email to
[email protected]. Send a complete description of your problem, an
explanation of exactly how you are using your unit, and a complete description of your
station.
FULL 12 MONTH WARRANTY
