KAT500 - Tune on QSY

[ANDY DURBIN]

I've had my KAT500 for about 18 months and I thought I had come to know it quite well.  Today I found something that surprised me.

The KAT500 utility has 2 "Memory Recall on Tune" options, one for MAN mode and one for Auto mode.  My understanding was that, if these options were not enabled, the KAT500 would not use RF frequency count or CAT TX frequency to change the tuning solution if the frequency was changed within band.

For MAN mode, with memory recall tune not checked, it appears that the KAT500 does still select tuning solutions as appropriate for the frequency received over CAT.  It does not change solutions if CAT frequency is not available and RF frequency is changed.

The utility "Tune on QSY" page says:

"Enable or disable memory recall tune on transmit frequency changes with the check boxes below."

However, the help file says:

"The tuner continuously monitors the transmit frequency. Beginning with firmware version 1.20, the tuner performs quick "memory recall" tunes as the transmit frequency changes within the current band, recalling the memory closest to the current transmit frequency.


If you prefer that the tuner not attempt to change settings for "in-band QSY" based on the transmit frequency count, uncheck the "Memory Recall Tune on QSY in Mode MAN" checkbox."


So it seems to be doing exactly what it says in the help file and there is no option to inhibit tuning changes if a new frequency is received over CAT.


I'm not suggesting any of this is a problem but it did surprise me.


Andy, k3wyc
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[ANDY DURBIN]

 December 17, 2019 I posted the following"

"I've had my KAT500 for about 18 months and I thought I had come to know it quite well.  Today I found something that surprised me.

The KAT500 utility has 2 "Memory Recall on Tune" options, one for MAN mode and one for Auto mode.  My understanding was that, if these options were not enabled, the KAT500 would not use RF frequency count or CAT TX frequency to change the tuning solution if the frequency was changed within band.

For MAN mode, with memory recall tune not checked, it appears that the KAT500 does still select tuning solutions as appropriate for the frequency received over CAT.  It does not change solutions if CAT frequency is not available and RF frequency is changed.

The utility "Tune on QSY" page says:

"Enable or disable memory recall tune on transmit frequency changes with the check boxes below."

However, the help file says:

"The tuner continuously monitors the transmit frequency. Beginning with firmware version 1.20, the tuner performs quick "memory recall" tunes as the transmit frequency changes within the current band, recalling the memory closest to the current transmit frequency.


If you prefer that the tuner not attempt to change settings for "in-band QSY" based on the transmit frequency count, uncheck the "Memory Recall Tune on QSY in Mode MAN" checkbox."


So it seems to be doing exactly what it says in the help file and there is no option to inhibit tuning changes if a new frequency is received over CAT.


I'm not suggesting any of this is a problem but it did surprise me."



After posting that I suggested to an owner of a TS890S, KAT500, and KPA500 that he should try disabling the QSY option as it might cure his annoying re-tunes during transmit.  It did not fix the problem.


After exchanging email with him I have been able to reproduce the problem and I think I understand it.


Disabling the "Tune on QSY" options, as previosly reported, prevents RF count re-tune but still allows CAT frequency re-tune.  It works fine if eirther one, or the other, is enabled but not when RF count and CAT can change the KAT500 frequency.


With Tune on QSY disabled and FCCS and FCMD at default values the KAT500 may retune during TX.  I have captured several events with my data logger and the sequence is the same each time.


What happens is that, when TX starts, the KAT500 is using the most recent CAT frequency.  If RF count frequency becomes different from CAT frequency then the "last observed frequency" is updated to RF count frequency.  Even if this frequency is in a different "bin" than CAT frequency there is no change in tuning solution as that is inhibited by "Tune on QSY" being inactive. All ok so far.


Now KAT500 sees the next CAT frequency update and, if it crosses a bin boundary from the RF count frequency, then there may be a retune.  Note that CAT frequency retune is not inhibited by clearing the "Tine on QSY" options.


The problem is most likely to be seen when the transmit frequency lies at the edge of a bin.  My tests used the FT8 nominal frequency of 1840 and 1840/1841 is the boundary between bins 183 and 184.


For the most recent test I modified my controller to be a verbose output of all KAT500 interrogation responses.  Normally it only reports changed values.  he is the event sequence for an FT8 TX with a TX freq of 1.841:


2019-12-24 15:23:00 F 1841; << F before TX is 1841
2019-12-24 15:23:00 C57; << Using bin 184 tuning solution
2019-12-24 15:23:00 L06;
2019-12-24 15:23:00 AN3;
2019-12-24 15:23:00 BYPN;
2019-12-24 15:23:00 SIDEA;
2019-12-24 15:23:00 0:00:11.586  New KPA_FS  - ^FS00;
2019-12-24 15:23:00 VSWR 1.31;
2019-12-24 15:23:00 VFWD 0;
2019-12-24 15:23:00 VRFL 0;
2019-12-24 15:23:00 FLT0;
2019-12-24 15:23:00 AMPI0;
2019-12-24 15:23:00 MDM;
2019-12-24 15:23:00 0:00:11.721  New IF - IF00001841000      000000003121010000;   <<TX starts
2019-12-24 15:23:00 F 1841; <<  F is still 1841
2019-12-24 15:23:00 C57;
2019-12-24 15:23:00 L06;
2019-12-24 15:23:00 AN3;
2019-12-24 15:23:00 BYPN;
2019-12-24 15:23:00 SIDEA;
2019-12-24 15:23:01 VSWR 1.31;
2019-12-24 15:23:01 0:00:11.828  New VSWR  - VSWR 1.31;
2019-12-24 15:23:01 VFWD 0;
2019-12-24 15:23:01 VRFL 0;
2019-12-24 15:23:01 FLT0;
2019-12-24 15:23:01 AMPI0;
2019-12-24 15:23:01 MDM;
2019-12-24 15:23:01 F 1841;
2019-12-24 15:23:01 C57;
2019-12-24 15:23:01 L06;
2019-12-24 15:23:01 AN3;
2019-12-24 15:23:01 BYPN;
2019-12-24 15:23:01 SIDEA;
2019-12-24 15:23:01 VSWR 1.09;
2019-12-24 15:23:01 0:00:12.073  New VSWR  - VSWR 1.09;
2019-12-24 15:23:01 VFWD 1250;
2019-12-24 15:23:01 VRFL 8;
2019-12-24 15:23:01 FLT0;
2019-12-24 15:23:01 AMPI0;
2019-12-24 15:23:01 MDM;
2019-12-24 15:23:01 0:00:12.209  New KPA_WS  - ^WS237 011;
2019-12-24 15:23:01 F 1840;
2019-12-24 15:23:01 0:00:12.216  New F  - F 1840; << new F 1840
2019-12-24 15:23:01 C57; << KAT still reports bin 184 solution
2019-12-24 15:23:01 L06;
2019-12-24 15:23:01 AN3;
2019-12-24 15:23:01 BYPN;
2019-12-24 15:23:01 SIDEA;
2019-12-24 15:23:01 VSWR 1.10;
2019-12-24 15:23:01 0:00:12.314  New VSWR  - VSWR 1.10;
2019-12-24 15:23:01 VFWD 1254;
2019-12-24 15:23:01 VRFL 15;
2019-12-24 15:23:01 FLT0;
2019-12-24 15:23:01 AMPI0;
2019-12-24 15:23:01 0:00:12.391  Sending F 1841; to KAT500 << Controller corrects to TX freq 1841
2019-12-24 15:23:01 MDM;
2019-12-24 15:23:01 F 1840; << KAT500 reports F 1840
2019-12-24 15:23:01 C7F; << Immediate change in tuning solution to bin 183 values
2019-12-24 15:23:01 0:00:12.471  New C  - 1341 pF
2019-12-24 15:23:01 L0E;
2019-12-24 15:23:01 0:00:12.487  New L  - 820 nH
2019-12-24 15:23:01 AN3;
2019-12-24 15:23:01 BYPN;
2019-12-24 15:23:01 SIDET;
2019-12-24 15:23:01 0:00:12.537  New SIDE  - SIDET;



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[ANDY DURBIN]

Please ignore previous post.  It was inadvertently send before editing was complete.

Andy, k3wyc
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[ANDY DURBIN]

Sorry for the inadvertent premature posting.  I'll try again -

After I had posted my observations on the behavior of KAT500 "Tune on QSY" option  I suggested to an owner of a TS-890S, KAT500, and KPA500 that he should try disabling the QSY option as it might cure his annoying re-tunes during transmit.  It did not fix the problem.

After exchanging email with him I have been able to reproduce the problem and I think I understand it.

Disabling the "Tune on QSY" options, as previously reported, prevents RF count re-tune but still allows CAT frequency re-tune.  It works fine if either one, or the other, is enabled but not when both RF count and CAT can change the KAT500 frequency.

With "Tune on QSY" not selected, and FCCS and FCMD at default values, the KAT500 may re-tune during TX.  I have captured several events with my data logger and the sequence is the same each time.

What happens is that, when TX starts, the KAT500 is using the most recent CAT frequency.  If RF count frequency becomes different from CAT frequency then the "last observed frequency" is updated to RF count frequency.  Even if this frequency is in a different "bin" than CAT frequency there is no change in tuning solution as that is inhibited by "Tune on QSY" being inactive. All ok so far.

Now KAT500 sees the next CAT frequency update and, if it crosses a bin boundary from the RF count frequency,  there may be a re-tune.  Note that CAT frequency re-tune is not inhibited by clearing the "Tune on QSY" options.

The problem is most likely to be seen when the transmit frequency lies at the edge of a bin.  My tests used the FT8 nominal frequency of 1840 and 1840/1841 is the boundary between bins 183 and 184.  A re-tune was seen at the start and end of every transmission when my TX freq was 1841. These re-tunes moved from bin 184 before TX, to bin 183 at start of TX, and then back to bin 184 at end of TX.

The paradox is that the transition to bin 183 tuning solution is triggered by a change of frequency from bin 183 to bin 184.

Bottom line is that disabling "Tune on QSY" option does not prevent RF count re-tune if CAT frequency is available to KAT500.

Detailed logger data available on request.

Andy, k3wyc
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