[TowerTalk] C4 Repaired -Coax Damage ?

[Jim Reid]

Aloha,

Well,  the Saturday morning repair to the broken boom of the
C4 only took 6 hours!!  Most of the time was spent taking
down the remnants of the antenna,  then literally driving  into
each boom half the splice tube -- very heavy Al tubing which
must have been 1 or 2 mils larger in OD than the 2" boom
tubing  ID  of the C4!  Anyway,  C4  is all repaired and back up
on the MA-550,  which is,  of course,  still collapsed down to
20 some  feet high.  Unfortunately,  found at the top,  that  it
appears  the upper section of the tower fell with enough force
to bend its way further down than the stop which was supposed
to stop it,  hi.  That repair is for some other day.

Now,  the back part of the broken C4  boom was dangling some
8 feet above the ground,  hanging suspended by the LMR-400
coax running up to the 40 meter Force 12 dipole.  Noticed it was
"kinked" or sharply bent at the bend from where it was dangling
from one of the US Tower coax support rings up on the tower.
And,  it must have had quite a bit of stretching force when it
stopped the antenna back part from the fall.

Thought nothing of it really,  used a bit of finger action to reshape
the coax back to round,  and put the antenna back up after the
boom splice was installed.

40 meter element now "hears" great,  but on transmit,  much
crackling and distortion occurs, almost sounding as if RF
arcing is occurring per fellows on the Hawaii Afternoon net
yesterday.  Don't know the innards of LMR-400,  but is it
possible it was permanently damaged in some way --
stretch of the inner conductor,  crack in it,  or now the outer
conductor is permanently pinched in toward the inner,  and
arcs.  This "arcing" occurs even with only 50 watts output!

I hope the problem can be solved by replacing the coax,
and that some problem to the 40 meter dipole,  unnoticed
yesterday when all was at ground level,  has not occurred.
Visually the dipole,  linear loading,  matching coil,  etc.,all
appeared just fine.

Can it be a damaged coax that would cause these symptoms?
Arc was too fast to see any impact on my vswr indicator,  but
guys on the net reported their S-matter reading seemed to
actually increase during or immediately after the crackle
sound,  or arc,  or whatever it is.

73,  Jim,  KH7M
On the Garden Island of Kauai



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