Elecraft KAT500/KPA500 PowerCombo only Partially Compatible with Modern Kenwood Rigs

[Jeff Hughes]

Just a little public service announcement that the Elecraft KAT500/KPA500 PowerCombo is only partially compatible with modern Kenwood radios.  To whit… the PowerCombo works with VFO A, but not VFO B.

Most modern rigs come with dual VFO’s, of course.  And many come with outright dual receivers.  This ability to quickly monitor and move between bands/frequencies comes in handy in a variety of scenarios.  And most of us happily bounce between these dual VFO’s without attaching any particular importance to one over the other.

The problem lies with the KAT500, which reliably tracks VFO A… but which cannot track VFO B.  The upshot being that if you’re operating VFO A, the KAT500/KPA500 PowerCombo will work as expected.  But as soon as you toggle over to VFO B the KAT500 will manifest with clacking relays with every Tx on/off transition and the KPA500 will instantly fault with High Reflected Power if it is brought online in SWR conditions that required a tuned solution from the KAT500.

Said differently, if you’re operating in conditions where native, un-tuned SWR is low – where you don’t need the KAT500, in other words - the KPA500 works perfectly.  But as soon as you move to a frequency with a moderate-or-higher SWR – a situation where you need the KAT500 to insert its tuned solution – it cannot do so, and the KPA500 faults.  The behavior is independent of the best practices usually espoused for the KAT500… always operate in ‘Manual,’ “train the tuner” to lock in inductor/capacitor settings in advance, and do that pre-tuning with 25-watts or more for greater accuracy.

This VFO B problem applies to the Kenwood TS-590SG, TS-890S, TS-990S, and perhaps others.

On their own, the KAT500/KPA500 PowerCombo are a remarkable addition to any shack.  Profound is the word I’ve often used to describe their impact.  However, the inability to use VFO B in conjunction with them is a pretty major failing.

I have no information one way or the other, but I suspect the KPA1500 also suffers from this issue.

Probably the thing that surprises me most is that this issue has apparently existed for years… and yet has not been socialized anywhere that I’m aware of.  Neither the Kenwood TS-890S User Manual nor the Kenwood TS-890S In-Depth Manual make mention that their VFO’s A and B implement slightly different character streams.  Elecraft’s KAT500 Automatic Antenna Tuner Owner’s Manual doesn’t mention that interfacing with Kenwood radios is a problem.  Fred Cady, KE7X (RIP), doesn’t mention it in his KPA500 Amplifier and KAT500 Tuner manual.  And it doesn’t appear to have made its way into any knowledgebase within Elecraft itself.  One wonders how many hours have been spent by Elecraft staff and Elecraft customers – and how many KAT500 and KPA500’s have been shipped back for repair – because of this one issue.

And that’s why I’m posting it here.

I’d like to thank Bob and Dick from Elecraft for their prompt, professional, and thoughtful assistance in helping me to look at the anomalous behavior I’ve always seen, but never could quite pin down, with my KAT500/KPA500.  And I’d especially like to thank Andy Durbin, K3WYC, for finally illuminating what was actually going on.  Andy submitted a defect report last fall and hopefully Elecraft will prioritize it at some point.

In the meantime, if you’re running a Kenwood rig and are contemplating adding the KAT500/KPA500 PowerCombo… be aware that there are issues.

73, Jeff K4EI

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[kc8wh.mh]

I noticed this issue exists when using the memory channels as well. My solution was to remove the Kenwood cable, just hook up the ptt line and let the KAT/KPA 500s sense the frequency and make the adjustments on the fly.They are really, really quickMike KC8WHSent from my Verizon, Samsung Galaxy Tablet
-------- Original message --------From: Jeff Hughes <[hidden email]> Date: 3/21/20  1:17 PM  (GMT-05:00) To: [hidden email] Subject: [Elecraft] Elecraft KAT500/KPA500 PowerCombo only Partially Compatible with Modern Kenwood Rigs Just a little public service announcement that the Elecraft KAT500/KPA500 PowerCombo is only partially compatible with modern Kenwood radios.  To whit… the PowerCombo works with VFO A, but not VFO B.Most modern rigs come with dual VFO’s, of course.  And many come with outright dual receivers.  This ability to quickly monitor and move between bands/frequencies comes in handy in a variety of scenarios.  And most of us happily bounce between these dual VFO’s without attaching any particular importance to one over the other.The problem lies with the KAT500, which reliably tracks VFO A… but which cannot track VFO B.  The upshot being that if you’re operating VFO A, the KAT500/KPA500 PowerCombo will work as expected.  But as soon as you toggle over to VFO B the KAT500 will manifest with clacking relays with every Tx on/off transition and the KPA500 will instantly fault with High Reflected Power if it is brought online in SWR conditions that required a tuned solution from the KAT500.Said differently, if you’re operating in conditions where native, un-tuned SWR is low – where you don’t need the KAT500, in other words - the KPA500 works perfectly.  But as soon as you move to a frequency with a moderate-or-higher SWR – a situation where you need the KAT500 to insert its tuned solution – it cannot do so, and the KPA500 faults.  The behavior is independent of the best practices usually espoused for the KAT500… always operate in ‘Manual,’ “train the tuner” to lock in inductor/capacitor settings in advance, and do that pre-tuning with 25-watts or more for greater accuracy.This VFO B problem applies to the Kenwood TS-590SG, TS-890S, TS-990S, and perhaps others.On their own, the KAT500/KPA500 PowerCombo are a remarkable addition to any shack.  Profound is the word I’ve often used to describe their impact.  However, the inability to use VFO B in conjunction with them is a pretty major failing.I have no information one way or the other, but I suspect the KPA1500 also suffers from this issue.Probably the thing that surprises me most is that this issue has apparently existed for years… and yet has not been socialized anywhere that I’m aware of.  Neither the Kenwood TS-890S User Manual nor the Kenwood TS-890S In-Depth Manual make mention that their VFO’s A and B implement slightly different character streams.  Elecraft’s KAT500 Automatic Antenna Tuner Owner’s Manual doesn’t mention that interfacing with Kenwood radios is a problem.  Fred Cady, KE7X (RIP), doesn’t mention it in his KPA500 Amplifier and KAT500 Tuner manual.  And it doesn’t appear to have made its way into any knowledgebase within Elecraft itself.  One wonders how many hours have been spent by Elecraft staff and Elecraft customers – and how many KAT500 and KPA500’s have been shipped back for repair – because of this one issue.And that’s why I’m posting it here.I’d like to thank Bob and Dick from Elecraft for their prompt, professional, and thoughtful assistance in helping me to look at the anomalous behavior I’ve always seen, but never could quite pin down, with my KAT500/KPA500.  And I’d especially like to thank Andy Durbin, K3WYC, for finally illuminating what was actually going on.  Andy submitted a defect report last fall and hopefully Elecraft will prioritize it at some point.In the meantime, if you’re running a Kenwood rig and are contemplating adding the KAT500/KPA500 PowerCombo… be aware that there are issues.73, Jeff K4EI______________________________________________________________Elecraft mailing listHome: http://mailman.qth.net/mailman/listinfo/elecraftHelp: http://mailman.qth.net/mmfaq.htmPost: mailto:[hidden email] list hosted by: http://www.qsl.netPlease help support this email list: http://www.qsl.net/donate.htmlMessage delivered to [hidden email]
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[Logan Zintsmaster]

I have a Flex 6600 with USB cables to both the KPA500 and KAT500 and the Flex software allows me to log the USB traffic.  I found that the KPA500 periodically polls the Flex with an IF;FA;FB command and gets an FA and FB response from the Flex for the frequency currently designated for .  The KAT500, on a separate USB port,  waits for a broadcast from the Flex when there is a change in frequency.  The Flex only broadcasts the VFO A frequency and it may take up to a second for the frequency info to arrive. Change bands too quickly and chaos may ensue with lots of red lights and relays clacking. It seems to me that an easy fix is to add the polling command to the KAT500 firmware, similar to the KPA500 firmware.

 I also think that I could build a  modified null modem for the KPA500 with a couple of diodes to connect the  KAT500 RX input and KPA500 RX input in parallel.  Then, when the KPA500 polls for frequency info both the KPA and KAT will get the data.  Sounds like a good "shelter in place" project.  Bring on the schematics...

And finally there must be a Raspberry Pi solution to periodically poll the Flex and then rebroadcast the information to both the KPA500 and KAT500.  You would need three serial/USB ports.  Might be an interesting Python project.  Bring on the software...

Similar solutions might be possible with the Kenwood radios.

73
Logan, KE7AZ

-----Original Message-----
From: [hidden email] <[hidden email]> On Behalf Of Jeff Hughes
Sent: Saturday, March 21, 2020 10:18 AM
To: [hidden email]
Subject: [Elecraft] Elecraft KAT500/KPA500 PowerCombo only Partially Compatible with Modern Kenwood Rigs

Just a little public service announcement that the Elecraft KAT500/KPA500 PowerCombo is only partially compatible with modern Kenwood radios.  To whit… the PowerCombo works with VFO A, but not VFO B.

Most modern rigs come with dual VFO’s, of course.  And many come with outright dual receivers.  This ability to quickly monitor and move between bands/frequencies comes in handy in a variety of scenarios.  And most of us happily bounce between these dual VFO’s without attaching any particular importance to one over the other.

The problem lies with the KAT500, which reliably tracks VFO A… but which cannot track VFO B.  The upshot being that if you’re operating VFO A, the KAT500/KPA500 PowerCombo will work as expected.  But as soon as you toggle over to VFO B the KAT500 will manifest with clacking relays with every Tx on/off transition and the KPA500 will instantly fault with High Reflected Power if it is brought online in SWR conditions that required a tuned solution from the KAT500.

Said differently, if you’re operating in conditions where native, un-tuned SWR is low – where you don’t need the KAT500, in other words - the KPA500 works perfectly.  But as soon as you move to a frequency with a moderate-or-higher SWR – a situation where you need the KAT500 to insert its tuned solution – it cannot do so, and the KPA500 faults.  The behavior is independent of the best practices usually espoused for the KAT500… always operate in ‘Manual,’ “train the tuner” to lock in inductor/capacitor settings in advance, and do that pre-tuning with 25-watts or more for greater accuracy.

This VFO B problem applies to the Kenwood TS-590SG, TS-890S, TS-990S, and perhaps others.

On their own, the KAT500/KPA500 PowerCombo are a remarkable addition to any shack.  Profound is the word I’ve often used to describe their impact.  However, the inability to use VFO B in conjunction with them is a pretty major failing.

I have no information one way or the other, but I suspect the KPA1500 also suffers from this issue.

Probably the thing that surprises me most is that this issue has apparently existed for years… and yet has not been socialized anywhere that I’m aware of.  Neither the Kenwood TS-890S User Manual nor the Kenwood TS-890S In-Depth Manual make mention that their VFO’s A and B implement slightly different character streams.  Elecraft’s KAT500 Automatic Antenna Tuner Owner’s Manual doesn’t mention that interfacing with Kenwood radios is a problem.  Fred Cady, KE7X (RIP), doesn’t mention it in his KPA500 Amplifier and KAT500 Tuner manual.  And it doesn’t appear to have made its way into any knowledgebase within Elecraft itself.  One wonders how many hours have been spent by Elecraft staff and Elecraft customers – and how many KAT500 and KPA500’s have been shipped back for repair – because of this one issue.

And that’s why I’m posting it here.

I’d like to thank Bob and Dick from Elecraft for their prompt, professional, and thoughtful assistance in helping me to look at the anomalous behavior I’ve always seen, but never could quite pin down, with my KAT500/KPA500.  And I’d especially like to thank Andy Durbin, K3WYC, for finally illuminating what was actually going on.  Andy submitted a defect report last fall and hopefully Elecraft will prioritize it at some point.

In the meantime, if you’re running a Kenwood rig and are contemplating adding the KAT500/KPA500 PowerCombo… be aware that there are issues.

73, Jeff K4EI

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[Dave wo2x]

Logan,

In the Flex USB cable setup just set the cables for Active TX Slice, so when you switch slices (vfo’s) the amp and tuner will follow the proper TX freq.

Dave wo2x


Sent from my iPad

> On Mar 21, 2020, at 9:17 PM, [hidden email] wrote:
>
> I have a Flex 6600 with USB cables to both the KPA500 and KAT500 and the Flex software allows me to log the USB traffic.  I found that the KPA500 periodically polls the Flex with an IF;FA;FB command and gets an FA and FB response from the Flex for the frequency currently designated for .  The KAT500, on a separate USB port,  waits for a broadcast from the Flex when there is a change in frequency.  The Flex only broadcasts the VFO A frequency and it may take up to a second for the frequency info to arrive. Change bands too quickly and chaos may ensue with lots of red lights and relays clacking. It seems to me that an easy fix is to add the polling command to the KAT500 firmware, similar to the KPA500 firmware.
>
> I also think that I could build a  modified null modem for the KPA500 with a couple of diodes to connect the  KAT500 RX input and KPA500 RX input in parallel.  Then, when the KPA500 polls for frequency info both the KPA and KAT will get the data.  Sounds like a good "shelter in place" project.  Bring on the schematics...
>
> And finally there must be a Raspberry Pi solution to periodically poll the Flex and then rebroadcast the information to both the KPA500 and KAT500.  You would need three serial/USB ports.  Might be an interesting Python project.  Bring on the software...
>
> Similar solutions might be possible with the Kenwood radios.
>
> 73
> Logan, KE7AZ
>
> -----Original Message-----
> From: [hidden email] <[hidden email]> On Behalf Of Jeff Hughes
> Sent: Saturday, March 21, 2020 10:18 AM
> To: [hidden email]
> Subject: [Elecraft] Elecraft KAT500/KPA500 PowerCombo only Partially Compatible with Modern Kenwood Rigs
>
> Just a little public service announcement that the Elecraft KAT500/KPA500 PowerCombo is only partially compatible with modern Kenwood radios.  To whit… the PowerCombo works with VFO A, but not VFO B.
>
> Most modern rigs come with dual VFO’s, of course.  And many come with outright dual receivers.  This ability to quickly monitor and move between bands/frequencies comes in handy in a variety of scenarios.  And most of us happily bounce between these dual VFO’s without attaching any particular importance to one over the other.
>
> The problem lies with the KAT500, which reliably tracks VFO A… but which cannot track VFO B.  The upshot being that if you’re operating VFO A, the KAT500/KPA500 PowerCombo will work as expected.  But as soon as you toggle over to VFO B the KAT500 will manifest with clacking relays with every Tx on/off transition and the KPA500 will instantly fault with High Reflected Power if it is brought online in SWR conditions that required a tuned solution from the KAT500.
>
> Said differently, if you’re operating in conditions where native, un-tuned SWR is low – where you don’t need the KAT500, in other words - the KPA500 works perfectly.  But as soon as you move to a frequency with a moderate-or-higher SWR – a situation where you need the KAT500 to insert its tuned solution – it cannot do so, and the KPA500 faults.  The behavior is independent of the best practices usually espoused for the KAT500… always operate in ‘Manual,’ “train the tuner” to lock in inductor/capacitor settings in advance, and do that pre-tuning with 25-watts or more for greater accuracy.
>
> This VFO B problem applies to the Kenwood TS-590SG, TS-890S, TS-990S, and perhaps others.
>
> On their own, the KAT500/KPA500 PowerCombo are a remarkable addition to any shack.  Profound is the word I’ve often used to describe their impact.  However, the inability to use VFO B in conjunction with them is a pretty major failing.
>
> I have no information one way or the other, but I suspect the KPA1500 also suffers from this issue.
>
> Probably the thing that surprises me most is that this issue has apparently existed for years… and yet has not been socialized anywhere that I’m aware of.  Neither the Kenwood TS-890S User Manual nor the Kenwood TS-890S In-Depth Manual make mention that their VFO’s A and B implement slightly different character streams.  Elecraft’s KAT500 Automatic Antenna Tuner Owner’s Manual doesn’t mention that interfacing with Kenwood radios is a problem.  Fred Cady, KE7X (RIP), doesn’t mention it in his KPA500 Amplifier and KAT500 Tuner manual.  And it doesn’t appear to have made its way into any knowledgebase within Elecraft itself.  One wonders how many hours have been spent by Elecraft staff and Elecraft customers – and how many KAT500 and KPA500’s have been shipped back for repair – because of this one issue.
>
> And that’s why I’m posting it here.
>
> I’d like to thank Bob and Dick from Elecraft for their prompt, professional, and thoughtful assistance in helping me to look at the anomalous behavior I’ve always seen, but never could quite pin down, with my KAT500/KPA500.  And I’d especially like to thank Andy Durbin, K3WYC, for finally illuminating what was actually going on.  Andy submitted a defect report last fall and hopefully Elecraft will prioritize it at some point.
>
> In the meantime, if you’re running a Kenwood rig and are contemplating adding the KAT500/KPA500 PowerCombo… be aware that there are issues.
>
> 73, Jeff K4EI
>
> ______________________________________________________________
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