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

John Regnault john.regnault at btinternet.com
Tue Nov 8 21:00:10 CET 2016


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 <mailto:w2hro.fn20 at gmail.com> >

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

To: Moon-Net <moon-net at mailman.pe1itr.com
<mailto:moon-net at mailman.pe1itr.com> >

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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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