Yaesu FT-100 Undocumented page 19

cable wrapped several times around the ferrite to block common mode current from
getting back into the rig. Ten meters seems particularly prone to the problem. Changing
the feedline length has also helped in some cases, but this seems to move the problem
around more than solving it at the root cause. Also, some owners have found that fixing
the grounding of the LPF board by adding solder around the screw holes and in some
cases tightening the screws or adding star washers was sufficient to make their grounding
problems go away.
However, there is a very effective modification that has worked in every case. The mod
involves fixing the grounding in the coax sockets on LPF of the radio and a metal shield
on the Main Unit. A degradation in the LPF grounding can cause the rig to break into
oscillation (even at lower power) causing the HIGH SWR icon to appear intermittently
even with a good antenna match on the higher HF bands. The mod will eliminate this
oscillation and the high SWR reports. Here are a few pictures of the factory installed
mod. The adhesive copper tape has been replaced screws or clamps that are attached to
the casting web. Note that on the upper strap, they have added a screw and the lower strap
was added and soldered to the shield as well as the coax and also screwed to the casting.
Before the factory mod
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