Inrad Roofing Filter installation instruction
Special thanks to George W2VJN and Trey from
Inrad (International Radio Corp)
for developing and merchandising this excellent mod!
Prepare the two coax cables
solder the braid of the coax cables in the connectors outer shield
Remove the bottom cover of the FT-920
Remove the top cover of the FT-920
Inrad CW Switchboard with Inrad 400 Hz and Inrad 1000 Hz filters
Inrad SSB Switchboard with Inrad 1800 Hz and Inrad 2800 Hz filters
Turn the radio over, so the bottom of the radio is facing up
Remove the large shielded assembly
Detach the four white strip wire harnesses from the main board
(the 4th strip wire one is underneath the large one on the left)
When the board is free, raise it to the vertical position
Lay the board like this
In this way it is very easy to do the work on the main board
Desolder C1111 (right in the middle of the photo)
Solder the coax cables to the pads left open by C1111
Ground the shields to the nearest ground pads
Re-install the board and set the radio on its left side
Prepare the mod board by soldering the red to +12V and the black wire to GND
I installed both wire to the SSB Switchboard MOD
The Instruction Manual says:
"Dress the coaxes and red wire through the opening in the casting near the front panel
on the right side of the radio as it lies up side down and trough the opening in the front center"
However, I could only find an opening in the casting on the left side of the radio!
The coax cables are much too short to use the opening on the left side
Therefore I made a solution myself, as you can see on the photos
With a file I made a little space in the aluminum casting of the radio
With a file you can make a little space in the top cover to give the coax cables some room
After re-assembling and switching on the radio everything worked fine!