[Icom] Strange IC-765 40 meter problem

Sun, 28 Jul 2002 14:38:26 +0100

Joe, I wonder if the 40 meter beam is the cushcraft 2 el  beam if so you
will have to pull it down and at the heat shrink loading coils use a razor
knife an cut around the sheet metal screws so you can check them they
originally did not use stainless steel screws and they rusted up and
corrosion set in plus the oxidation probly aluminum oxide is a Great
insulator. by just cutting these windows you can clean the connection and
put stainless steel  screws in most of us drilled thru using screw s nuts
and loc washer ALL STAINLESS STEEL   I also put some of Mosleys penetrox
while installing the connection. then did a very gud tape seal over this
portion of the coils both ends check all 4 coils and replace the sheet metal
screws with stainless steel.
      I belong to a contest club and there are many of these beams being
used and all had to be cleaned and replacing the non stainless steel screws,
If you look closely at the bump in the heat shrink over these screws you
will see the stress on it and pin holes allowing water to seep in and do it
dirty work.
    I have had 4 of these beams and all had same problem.  and i know
personally of at least a dozen.  Oh MAKE SURE YOU SEAL THE TAPE REPAIR AT
THE ENDS OF THE COILS A FEW COAT OF SOME SEALER CLEAR CRLYON OR ??
Steve K2SB
----- Original Message -----
From: "Matt Erickson" <[email protected]>
To: <[email protected]>
Sent: Sunday, July 28, 2002 14:02
Subject: Re: [Icom] Strange IC-765 40 meter problem


> Check all coax connections. The root of the problem might be that you have
> a loose or corroded element on your 40 mtr beam.
> Windy days would show that the element is moving around, and has a poor
> mechanical/electrical connection. If one element tip became disconnected,
> would severely unbalance the beam (which is a balanced system), and cause
a
> mismatched system, even if the element is not the driven element.
>
> 73 de Matt KK5DR
>
> At 06:43 AM 7/28/02 -0400, you wrote:
> >For brief background, I began noticing something interesting with my
> >IC-765's performance on 40 meters earlier this year.  The receive level
> >would occasionally reduce considerably and suddenly (i.e. one second the
> >band sounds normal, the next it's severely attenuated).  After hitting
the
> >keyer, even briefly, everything returned to normal.  I noticed this
> >happened more in windy conditions than not, so assumed it was my 40 meter
> >beam.  Also noticed that sometimes the SWR would go up to 3:1, then back
> >to a more normal 1.4:1.
> >
> >Decided to replace the balun and coax on the beam.  Also checked
> >everything else out while we were up there.  All looked fine.  Came back
> >down, fired things up, had a 1.2:1 SWR.  Stations sounded fine.  Then the
> >receive problem kicked in again, and the SWR is now > 3:1!!
> >
> >Is it possible this is something with the 765??  Has anyone seen or heard
> >of this happening?  It's so bad that even the antenna tuner won't knock
> >the SWR down.  I don't have another rig to test it with, so now I'm
> >stumped.  But we've replaced virtually everything that can be replaced on
> >the 40 meter beam, so I'm now out of ideas.
> >
> >Any suggestions will be more than welcome.
> >
> >73, Joe KQ3F
> >
> >----
> >Your Moderator: Dick Flanagan W6OLD, [email protected]
> >Icom FAQ: http://www.qsl.net/icom/
>
> ----
> Your Moderator: Dick Flanagan W6OLD, [email protected]
> Icom FAQ: http://www.qsl.net/icom/
>