> 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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