Install the W4RT CW Filter Posted on Sunday, 4/6/2008
The Icom 718 is a great CW rig, however without a good filter, CW
cannot be enjoyed to it's fullest extent. A CW filter in the radio
works on the IF section, where as I was previously working with an
external audio DSP unit to filter (Radio Shack DSP-40) there is a
problem with close by signals and the AGC. The best overall solution
is to install a true IF filter.
The filter comes with instructions, most of which is not needed.
With the bottom off, the audio board is clearly visable. The included instructions are
a bit over whelming and most of it is not necessary. The two RF connectors in the back and
6 screws is all that is needed to be removed to flop the board out and install the filter.
Make sure you remove the two heat sink clips on either side.
The screws are out, and the two RF cables are unplugged. The board is ready to be worked out and
flopped over.
Here is where the filter goes.
Only 4 legs come though the board to be soldered.
Board in place, legs ready for solder.
The W4RT filter board is in place, however note that it cannot sit flush on the main board.
The radio was carefully set up to solder the 4 legs and then lay it back down.
I managed to capture an image of Digipan's waterfall with and without the filter engaged so you can see
how it does.
The install took no time and the benefits were easily recognized. Refer to the owner's manual on how to
set up the rig though the initial set menu for the filter that was installed.
The W4RT filter uses a Collins mechanical filter and at the date of writing was purchased for $109, which
is much less than the $189 for the OEM Icom filter.
