After Purchasing the Yaesu FT-847 for mainly satellite work and as a backup HF rig, I decided to give the filters a little upgrade. I started looking around for the original Yaesu parts online and found articles of folks replacing these with aftermarket filters which are somewhat narrower and seem to perform better according to those who have made the modifications before me.
A complete view of the 3 filters 2 for receive and one transmit (stock)
The above image is what I finally came up with and as you can see it is a little more involved then just replacing the 2 filters (left side) I ended up having to run small shielded coax type cables soldered into the original circuit boards where the Yaesu filters sit and due to their larger size (aftermarket after-all) I had to double sided tape them to an area with some space. The cover would not close if I had left it where the stock filters would have gone. Be carefull when routing, re-attach everything where you found it and keep away as much from other wires as possible.
The new Inrad filters installed
I decided to got with the inrad brad filers for the radio 250hz (#704c) for the CW portion and 2100hz (#702c) for the SSB portion. Note that these are receive only filters. Will not affect the transmit portion of the unit.
A Closeup of the 2 old filter circuit boards with the new coax attached
Lastly here is the final closeup of the unit after it was installed and the cables were routed. I zip tied them together to keep them more secure and also made for easier routing as I did not want to damage the delicate solder joints on the bottom.
Final Result: Excellent! I would highly recommend doing this modification if you are trying to work SSB or CW on HF or on satellite. Feels like I have a brand new receiver and this unit is now going to be part of my shack for the foreseeable future.
If you find something incorrect, have an update, or if there is something you would like to see added to the site, drop me a line here. I like to keep things as up-to-date and as accurate as possible. Thank you! – Lucas / W6AER
