[Yaesu] FT847: 70cm RX path

["Hans Bößl"]

Hallo,

is there someone who could explain me, why there are two HELIX filter branches in the RX chain of the FT847 after the preamplifier.
I did some measurements and could do only an improvement of the passband by adjusting the "L" or "LOW" branch. I couldn't find any influence which was worth mentioning on the "H" or "HIGH" branch.

Another mystery is how the impedance matching of the build in 455KHz filter (CFJ455K)is done? I can't seen any precautions.

And I've also another question: Where could I get the service manual for the FT847  ? Is there an Internet adress where this manual is stored just by chance?

Would be realy great got get some answers!

vy 73 Hans, DL9MCC