There was a similar, but not quite the same, issue where the original 565
caused arc fault errors in Acom amplifiers. The 565's bipolar PA output
transistors seemed to be the cause and the problem disappeared with the 566
that used different (FET) output transistors. The work-around back then
was to use a high pass filter between the 565 and the Acom. That
eliminated the arc faults, which seemed to be related to low frequency
spurs in the 565 rf output.
73, Barry N1EU
On Tue, Aug 10, 2021 at 11:06 AM Bruce Small <brucesmall73@gmail.com> wrote:
> I need to tap the collective wisdom of this group regarding an
> interesting problem.
>
> I have an ACOM 700S solid state amplifier that is driven either by an
> Orion (565) or an Orion II (566).
>
> When I use the 565, the amp faults on 10 meters only. The protection
> fault indicates high SWR and excessive drive current. This happens
> regardless of the amount of drive power from the Orion, even with the
> PWR control turned all the way down, providing about 6 watts of drive.
> On CW, the fault occurs on key-down, while on SSB and FT-8 the amp
> faults on key-up, at the end of a transmission. Engaging the TUNE button
> does not produce the fault. All bands other than 10 meters work normally.
>
> Using the O II, none of this behavior occurs, and the amp plays happily.
>
> Steps taken without solving the problem include:
> *Replace coax jumpers (they needed it anyway)
> *Replace arc plug in lightning arrestor
> *Remove all components from the signal path (watt/SWR meter, tuner, coax
> switch, lightning arrestor) and connect directly to the coax run to the
> antenna
> *Connect to a different antenna fed through a separate coax cable
> *Control the amp using Keying Loop 1, Keying Loop 2, or the Amp Key output
> * I don't have a good oscilloscope, but to the best of my ability to
> observe, the CW waveform was well-shaped and didn't show any spikes in
> power.
>
> All of this points to an issue with the Orion on 10 M - what else should
> I look at?
>
> Thanks & 73,
> Bruce KM2L
>
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>
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