MFJ MFJ-726 User Manual

MFJ-726 NARROW AUDIO CW FILTER FOR MFJ TRANSCEIVERS

GENERAL DESCRIPTION
The MFJ-726 Narrow Audio CW Filter reduces i nterference ca used by
adjacent-channel stations and atmospheric noise. A dual op-amp
provides two sec ond-ord er mu ltiple-f eedb ack acti ve filters w hich provide
an extremely narrow audio passband centered at 700-Hz. The MFJ-726
filter is activated by a pushbutton switch located on the
transceiver's back panel.

INSTALLATION PROCEDURE

1. Disconnect power source and remove transceiver cover (6
screws). Set cover aside without stressing speaker leads.

2. Remove pushbutton from filter's IN/OUT switch by pulling. Look
to right-rear of transceiver for a 4-pin header and switch access
hole in rear panel.

3. Remove the black shorting clip which is located on the two
middle pins of the 4-pin header . Tape the c lip to the inside of
the box for safe keeping.

4. Place filter switch shaft through rear panel access hole.
CAREFULLY lower module onto header so pins mate into filter
socket.

5. Seat filter on support studs and secure in place with #6-32
screws. Reinstall pushbutton.

6. Test operation. I f filter fai ls to operate, confirm all four
header pins are inserted into the module.