MFJ-941EK Tuner Kit
Instruction Manual
- 24 -
TESTING
[ ] Reduce transmit power to 20W.
[ ] Change the range switch to
30W
(button out).
[ ] View
Forward
scale and apply power. Set R7 for 20W (200 on 0-300 scale).
Reflected Power Setup:
This procedure uses the same setup,
except the Transmitter
and
Coax-1
connections are reversed
to measure reflected power. Note that applied power
levels will be lower (20W and 5W).
[ ] Connect radio to
Coax-1
.
[ ] Connect wattmeter and load to
Transmitter
.
[ ]
Antenna Selector
remains set on
Bypass, Coax-1
.
[ ] Reset the power-range switch for
300W
(button in).
[ ] View the tuner's
Reflected
scale. Apply 20W and set R6 for a 20-W reading.
[ ] Reduce power output to 5 Watts. Change range switch to
30W
(button out).
[ ] View
Reflected
Meter, set R5 for 5-W* ("50" on the 0-60W scale).
*If your radio will turn down to a lower power level, use a 2W or 3W reference
instead of 5W.
T-Network Check:
This procedure checks the RF path through the T-network to confirm the three
main tuner components are connected properly and functional.
[ ] Connect your transceiver back to
Transmitter
.
[ ] Connect your dummy load and reference meter back to
Coax-1
.
[ ] Return the range switch to
300W
(button in)
[ ] Change the tuner
Antenna Selector
to
Tuned, Coax-1
.
[ ] Set the
Inductor
switch to
"J"
[ ] Set the
Transmitter
and
Antenna
controls to "0" (capacitors fully meshed).
[ ] Starting low, gradually increase power to 100W.
Forward power should read close to 100W, SWR near "0". To further verify
control functions, momentarily change the
Transmitter
and
Antenna
settings --
you should see significant changes in SWR. Moving the
Inductor
setting by one
step in either direction should also increase SWR (do not switch it with RF power
applied!!).
