It seems Yaesu designed the FT-817 to be used
for VHF/UHF transceive in the over-the-shoulder
walking mode. Hence the BNC on the face pointing
upwards, compatible with VHF/UHF duckies.
There is no provision for mounting an efficient
HF whip antenna on the FT-817 directly.
So, those of us who desire to use it effectively
in a "walking HF" configuration will require
an additional structure.
The concept/design for such a structure might include:
1)ergonomic backpack for radio mounting
2)standard thread whip mount
3)manual or semi-auto antenna tuner
4)auxiliary battery pack
Such a concept could form the basis for some
entrepreneurial aftermarket product activity.
The "Worldpack (tm)" backpack is a good
start, but the existing model ,designed
for ICOM-706, is not optimum for the tiny FT-817.
73---Bonnie KQ6XA