Corsair 9Mhz IF Mods

9Mhz Filter Socket Mod

The 2.4Khz 9Mhz filter is soldered to the 9Mhz filter board. If you want to experiment with other 9Mhz filters, it is a huge advantage and relatively easy to install filter pin sockets on the 9Mhz filter board. I used HARWIN - H3182-05 sockets from Newark.

1. Remove the 9Mhz filter board from the chassis. First unplug the 5 connectors - they are all clearly labelled. Carefully unscrew the two nuts - do NOT push the mounting screw shafts back toward the PA compartment.

2. Unsolder the 2.4Khz filter (solder sucker, solder wick, etc)

3. Increase the filter pin hole size to 5/64 in. to accommodate the sockets. I used a Dremel and successively drilled through with 3/64, 1/16, and 5/64 in. bits - you want to preserve the integrity of the pcb solder pads.

4. To ensure that the sockets are installed squarely, push 4 sockets on to the pins of a Ten-Tec filter after squaring the filter pins with pliers. Now install the filter with sockets attached through the four holes you just drilled out. Make sure the sockets are completely seated. Solder the sockets to the pc board. Remove the "guide" filter.


5. Optional: before installing the modified filter board on the chassis, fully extend the mounting screw shafts outward to their full extent and apply Loctite 242 where the mounting screw shafts exit the Corsair chassis. Allow the Loctite to set for 24 hours. Applying Loctite will minimize the chance that you will accidentally push the screw shafts back through the chassis and forcing you to open up the PA compartment to fish them out.


6. After the Loctite sets, carefully reinstall the filter board avoiding exerting inward pressure on the mounting screws. Re-attach the five connectors. Install the desired filter.

9Mhz Roofing Filter Mod

The Inrad's Roofing Filter Mod kit should be installable in the Corsair. When operating cw, I can hear a bit of 9Mhz filter blowby - high pitched signals unaffected by 6.3Mhz i.f. filtering. This blowby along with immunity from strong adjacent signals should be improved by the roofing filter . Below is the recommended install location on the Corsair's RF Mixer board from W2VJN. Break the circuit at "X" and install the roofing filter board there. I don't know anyone who has actually done this installation.