The "tighten the circuit board screws" isn't an oscillation fix unique to the
FT857/897. I have had to do it to a Yaesu FT100D and Icom 551D as well, and
have had a couple of friends have to do it to their Icom 706mKIIG as well.
73s John AA5JG
--- On Fri, 11/28/08, Dan Evans <dan.evans@insightbb.com> wrote:
> From: Dan Evans <dan.evans@insightbb.com>
> Subject: Re: [VHFcontesting] rig recommendations for portable
> operation--FT897D comments
> To: vhfcontesting@contesting.com
> Date: Friday, November 28, 2008, 8:28 AM
> OK, now I understand.
>
> I remember reading about the oscillation issue before, but
> even though I
> have made several hundred 6m contest QSO's in the past
> year mine has
> never had a problem. My rig was a "one owner",
> but was practically
> unused when I bought it. But, it did have one repair.
> Another common
> problem with the '897 is the RIT knob is very fragile.
> Just before
> shipping the rig to me the previous owner knocked the rig
> over on a
> table, the knob hit and broke. He sent it in and had it
> repaired.
> I'll bet while they were fixing the knob, the PCB
> board was tightened.
> And so, no 6m problems with my rig...
>
> I know I couldn't believe that I would be
> "lucky" enough to get one
> without a problem. It usually works the other way for me!
>
> I'm also on the 897 yahoo group, but I have to admit I
> ignore most of
> the traffic there. Most of it seems to be the same
> "entry level"
> questions / info over and over... I'll likely drop that
> list soon.
>
>
> 73
> Dan
> --
> K9ZF /R no budget Rover ***QRP-l #1269 Check out the Rover
> Resource Page at:
> <http://www.qsl.net/n9rla> List Administrator for:
> InHam+grid-loc+ham-books
> Ask me how to join the Indiana Ham Mailing list!
>
>
>
> Alex wrote:
> >> I would NOT recommend a FT 857 or 897
> for contesting. Both
> >> have a problem with 6 meters that ultimately ends
> up with a trip for
> >> repair associated with the final amp stage. This
> problem has been
> >> around for years, starts with an oscillation and
> ends up with low
> >> output or blown finals.
> >>
> >
> > I had that issue years ago with my 897, oscillating on
> 6m that is. I wrote
> > about it on the 897 group on Yahoo. I bet you can
> still find it in the
> > archives.
> >
> > Usually the first indication is a high SWR indication,
> on the display, on a
> > well matched antenna system (not on a dummy load!).
> This indicates that the
> > rig is oscillating on a frequency outside the range
> for which the antenna
> > system provides a good match. The cause is bad
> grounding of the PCB, which
> > in turn allows for all kinds of RF paths to exists,
> causing RF feedback and
> > break the amplifier stages into oscillation. The
> remedy is simple. Tighten
> > all screws that mount the PCB(s) onto the chassis. I
> found that in my rig
> > *all* screws were .25 turn loose. I don't know if
> they just don't apply
> > enough torque on the screws on the assembly line, or
> if the slight expansion
> > and contracting of the chassis due to temperature
> variations is the cause.
> > However, my rig has never displayed the problem since
> I tightened the
> > screws.
> >
> > 73,
> > --Alex KR1ST
> > http://www.kr1st.com
> > http://www.airlinkexpress.org
> >
> >
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