[hpsdr] Pure Signal and ARC FAULT of linear amplifier

[Scott Traurig]

Please see below...

On Thu, May 2, 2019 at 1:31 AM Tokio Endo <endotokio at gmail.com> wrote:

>
> Recently I’ve begun to use ACOM2000A, manufactured in 2009 with original
> EBS, instead of TL-922. The other equipment remains the same as TL-922
> configurations, including a directional coupler, Xtronic XDC-4SO. The
> reason why I preferTL-922 is EBS of ACOM2000A which changes the bias during
> transmission which causes the abrupt change of amplifier behavior which I
> think it is not good for Pre-distortion.
>

Any type of dynamic bias control in an external amplifier will cause
PureSignal not to work. The amplifier bias control and PureSignal will
"chase each other's tails" and you will never get a stable solution.
Dynamic bias must be turned off or defeated somehow.


> Using ACOM2000A with Pure Signal, more precisely the PS button ON of
> PowerSDR, ACOM2000A trips due to ARC FAULT while I have SSB QSO. In CW and
> FT8, ARC FAULT never happens even with 1.5KW. FYI I don’t use 1.5KW for
> FT8.


> With PS button OFF, NO ARC FAULT occurs with SSB QSO. I am obliged to
> think that the CAUSE of ARC FAULT is Pure Signal due to a very short period
> of spike of an exciter power, maybe, during the period when EBS works as
> well as the adaptive functionality of Pure Signal.
>

The problem is not with PureSignal, and there are no "spikes" or overshoots
in the RF waveform coming out of the Hermes. It is possible that the TS-940
amp could somehow be at fault. However experience suggests that it is the
ACOM that is the problem. Many people have reported issues with PureSignal
and ACOM amplifiers. For example:

https://apache-labs.com/community/viewtopic.php?f=15&t=2593&p=4326&

73,

Scott/w-u-2-o
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