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Inrad Roofing Filter in the Yaesu FT-920


Yaesu FT-920

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!


 
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