[Moon-Net] TS-2000X SSB TX Output Power Ramping

Paul Andrews w2hro.fn20 at gmail.com
Tue Nov 8 23:01:26 CET 2016


John,

Good to know.   I successfully used the AFSK Input port on my previous
radio the FT-847.   I think Yaesu did a better job.   The AFSK input was
not subject to speech processing or front panel microphone level control.
It was a clean way to interface the SignaLink.    Obviously, I didn't
expect that the TS-2000X ACC2 input would have this issue.   I will operate
2M EME with this TX ramp up just to see if it affects the quality of my
QSOs.   The TX level ramp is kind to SSPAs.   Your 8877 is a very resilient
amp.   SSPAs are subject to damage for over drive.   This ACC2 interface
problem may actually help protect the SSPA.   We'll see.

73 - Paul - W2HRO




On Tue, Nov 8, 2016 at 3:00 PM, John Regnault <john.regnault at btinternet.com>
wrote:

> Paul,
>
>
>
> I have used several TS2000 (X) both for EME and FSK441 meteor scatter over
> 12+ years.
>
> I have been aware of this issue for many years and just do not use the
> ACC2 port. The mod looked like a major nightmare!
>
> I run an external sequencers which in turn switches the TS2000 to TX and I
> use the mic input for all modes.
>
> Like Joe K1JT has said ‘NO PROCESSOR’ and further I would say reduce the
> audio drive until you have almost no alc. Overdrive and clipping ‘does’
> affect the quality of a JT65 transmission. Poor(clipped, compressed,
> overdriven) JT65 transmissions decode badly!
>
>
>
> Over 3000 JT65 EME QSO’s and over 1000 FSK MS QSO’s driving a 8877
> amplifier and the only thing that has gone wrong is oxidised crimp
> connections on the power lead.
>
>
>
> 73
>
> John G4SWX
>
>
>
> Date: Tue, 8 Nov 2016 09:53:03 -0500
>
> From: Paul Andrews <w2hro.fn20 at gmail.com>
>
> Subject: [Moon-Net] TS-2000X SSB TX Output Power Ramping
>
> To: Moon-Net <moon-net at mailman.pe1itr.com>
>
> Message-ID:
>
>                <CAOsf+NQYZazuD2kjTz3HfLQonjD7Eohx23M
> 1LeRaX45cYd+ABA at mail.gmail.com>
>
> Content-Type: text/plain; charset=UTF-8
>
>
>
> Kenwood has reported that TS-2000X TX Output Power Ramping when using the
> ACC2 interface is a real bug / "feature" affecting early models.
>
> My radio is SEPT 2001.  This appears to be a relatively rare bug unless
> many operators just haven't seen it because they use the front panel
> microphone jack and not the ACC2 interface.
>
>
>
> This bug affects only SSB transmissions originated from the ACC2 port.
>
> FM is unaffected.  WSJT transmissions using the front panel Microphone
> jack are unaffected.
>
>
>
> Kenwood sent me the detailed factory authorized upgrade procedure.   I
>
> have the procedure document in PDF form and will provide it to anyone who
> asks.  Is there a good place that this procedure could be posted for all
> interested to review?
>
>
>
> The fix is not trivial.  The easy part is removing 1 resistor and adding
> another.  Removing and replacing a 150 pin SMD IC chip is a little more
> complicated and then the final step is a full upgrade of CPU and DSP
> firmware.  At the end of the procedure Kenwood writes, "when complete - no
> adjustments are needed".  :)
>
>
>
> It appears that this TX power ramping is written into the DSP.
>
> Kenwood could have offered this as an option.  The idea of "soft start"
> for audio digital modes is interesting.  This "soft start"
>
> could be easily written into WSJT and could minimize the TX power
> overshoot problem that SSPA owners worry about.
>
>
>
> I have decided (like others) that this 2 second TX power ramp is actually
> a very valuable "FEATURE" because it helps treats solid state amps kindly
> by avoiding the abrupt 0 to 100% output transition or
>
> overshoot spikes.   Hey - I'm making lemonade out of lemons.   I have
>
> not tested to see if this TX Power ramp exists on 70cm or 23cm.  I'll be
> testing soon.
>
>
>
> Thanks for all your responses to my original question.  In summary, 2 moon
> net readers knew this was a TS-2000 bug and had experience with it.  10
> others had not experience this issue.
>
>
>
> 73 - Paul - W2HRO
>
>
>
>
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