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KAT500/KPA500 - Sanity Check Please

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k4vd

KAT500/KPA500 - Sanity Check Please

I'm reading the specifications for the KAT500. Typical matching range from
3-30 MHz is 10:1 SWR for 600 watts.

This means that if the KAT500 utility reports "Bypass VSWR" in excess of
10:1 then the KPA500 should not be set to operate.

I'm running a dipole cut for 80 and fed with 600 ohm ladder line as a
multiband antenna. The BALUN is right outside my window. I have the option
of 1:1, 4:1, 9:1 and 12:1 I think. They are DXE brand. My job then is to
pick the right BALUN to provide <10:1 SWR on the bands of interest. I hoped
this would be at least 80-20 if not 80-10.

Not sure which BALUN is plugged in right now but on 80 meters I'm showing a
bypass VSWR of 12.00 and VSWR of 1.6:1. This means I cannot use the KPA500
on 80 regardless of the good match the KAT500 provided.

Should the key line cables from the KAT500 to the KPA500 and the rig (using
a Flex) prevent keying the amp if the SWR exceeds 10:1 automatically?

If I want better than that then I have to find another antenna tuner with a
wider SWR range at 600 watts or a different antenna?

Can anyone guess at the matching range of the KAT500 at 100W?

The thing is... I think I have a dead amp.

Kev K4VD
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Bob McGraw - K4TAX

Re: KAT500/KPA500 - Sanity Check Please

My station is a K3S, KPA500, KAT500.    The antenna is a 250 ft center
fed wire with 450 window line that runs from the feed point on the
antenna all the way to the operating position where the 450 line
terminates into a 1:1 current balun on the shelf just above the amp and
tuner. I use a common mode choke between the balun and the KAT500.
That common mode choke is a model 8232 purchased from The Wireman.   It
is 18" length of coax with about 75 ferrite beads of #43 material.
This provides additional common mode rejection not offered by the
balun. I can work 160M through 6M with this configuration.

The KAT500 is set to automatically switch to BYPASS if the SWR is less
than 1.3:1.   And it is set to bypass the amp if the SWR is greater than
1.5:1.

A 10:1 SWR basically says the impedance is somewhere between 5 ohms and
500 ohms.   In order to attain this you will need to use both, depending
on band a 1:1 balun or a 4:1 balun as likely with your antenna the
antenna on 40M presents a Z of 3000 ohms or so. Then the length of the
feed line is critical as it becomes part of the impedance acting as a
matching length of line.    The "600 ohm" impedance of the line is of
little importance as you are matching the entire complex load and not
just the impedance of the line. Many hams seem to think, incorrectly,
they need to match the impedance of the feed line.

If your showing a Bypass SWR of 12:1 then you are outside of the range
of the KAT500. You are using the wrong balun or you need to change the
600 ohm feed line length to attain a better / lower SWR.

The keying line between the KAT500 and KPA500 should interrupt the PTT
line if the matched SWR exceeds 1.5:1. This is a setting defined in the
KAT500 configuration by the user and the KAT500 Utility.

The best suggestion, make changes to the antenna such that the SWR
falls within the range of the tuner. As to the amp, connect a 50 dummy
load to one output of the tuner {you do have one?} and then see how the
combination of amp and tuner behave.

I'd say the matching range of the KAT500 is the same at 100 watts.   The
KAT500 manual {page 2} clearly defines the matching ranges and power
ratings.

73

Bob, K4TAX

On 1/25/2019 10:47 PM, Kevin der Kinderen wrote:

> I'm reading the specifications for the KAT500. Typical matching range from
> 3-30 MHz is 10:1 SWR for 600 watts.
>
> This means that if the KAT500 utility reports "Bypass VSWR" in excess of
> 10:1 then the KPA500 should not be set to operate.
>
> I'm running a dipole cut for 80 and fed with 600 ohm ladder line as a
> multiband antenna. The BALUN is right outside my window. I have the option
> of 1:1, 4:1, 9:1 and 12:1 I think. They are DXE brand. My job then is to
> pick the right BALUN to provide <10:1 SWR on the bands of interest. I hoped
> this would be at least 80-20 if not 80-10.
>
> Not sure which BALUN is plugged in right now but on 80 meters I'm showing a
> bypass VSWR of 12.00 and VSWR of 1.6:1. This means I cannot use the KPA500
> on 80 regardless of the good match the KAT500 provided.
>
> Should the key line cables from the KAT500 to the KPA500 and the rig (using
> a Flex) prevent keying the amp if the SWR exceeds 10:1 automatically?
>
> If I want better than that then I have to find another antenna tuner with a
> wider SWR range at 600 watts or a different antenna?
>
> Can anyone guess at the matching range of the KAT500 at 100W?
>
> The thing is... I think I have a dead amp.
>
> Kev K4VD
> ______________________________________________________________
> Elecraft mailing list
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>

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ANDY DURBIN

KAT500/KPA500 - Sanity Check Please

In reply to this post by k4vd

"Should the key line cables from the KAT500 to the KPA500 and the rig (using a Flex) prevent keying the amp if the SWR exceeds 10:1 automatically?"

I'd suggest installing and running the KAT500 Utility. It will give a clear indication of whether the KAT500 is inhibiting the KPA500 key line (Operate tab, others, Amp Key Interrupt) . To the best of my recollection Bypass VSWR is never used to interrupt the keying line. However, if you are bypassed, and transmitting with excessive VSWR, then the key line will be interrupted because of the current VSWR. VSWR thresholds can be set with KAT500 Utility, Configuration tab, VSWR thesholds.

Andy, k3wyc

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Wes Stewart-2

Re: KAT500/KPA500 - Sanity Check Please

In reply to this post by Bob McGraw - K4TAX

Not necessarily. That is true for purely resistive (real) loads, but for
reactive loads with the same SWR the real part can be much different and may or
may not be matched even at <10:1.

Wes N7WS

On 1/26/2019 8:16 AM, Bob McGraw K4TAX wrote:
> ...
>
> A 10:1 SWR basically says the impedance is somewhere between 5 ohms and 500
> ohms....
> 73
>
> Bob, K4TAX

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Dick Dievendorff-4

Re: KAT500/KPA500 - Sanity Check Please

In reply to this post by ANDY DURBIN

Bypass SWR is the SWR of the antenna, measured with the ATU bypassed.

The ATU does interrupt the amp key line when the bypass SWR is too high AND there is enough forward power to endanger ATU components. It’s a fault.

At 3:1 bypass SWR the ATU can handle a kilowatt.

At 10:1 bypass SWR the ATU can handle the full output of a KPA500, but not 1000 watts.

Some antennas higher than 10:1 SWR can be matched. But RF forward power needs to be reduced a bit.

But some amazingly poor antennas can do the job if that’s all you have available. The ATU shouldn’t stop you from using a bad antenna until the combination of power level and high bypass SWR endanger ATU components.

There is another “amp key interrupt” SWR threshold to protect the amp; that’s the SWR as seen by the amp, with ATU matching.

73 de Dick, K6KR

> On Jan 26, 2019, at 10:17, Andy Durbin <[hidden email]> wrote:
>
> "Should the key line cables from the KAT500 to the KPA500 and the rig (using a Flex) prevent keying the amp if the SWR exceeds 10:1 automatically?"
>
> I'd suggest installing and running the KAT500 Utility. It will give a clear indication of whether the KAT500 is inhibiting the KPA500 key line (Operate tab, others, Amp Key Interrupt) . To the best of my recollection Bypass VSWR is never used to interrupt the keying line. However, if you are bypassed, and transmitting with excessive VSWR, then the key line will be interrupted because of the current VSWR. VSWR thresholds can be set with KAT500 Utility, Configuration tab, VSWR thesholds.
>
> Andy, k3wyc
>
>
> ______________________________________________________________
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ANDY DURBIN

Re: KAT500/KPA500 - Sanity Check Please

In reply to this post by ANDY DURBIN

"The ATU does interrupt the amp key line when the bypass SWR is too high AND there is enough forward power to endanger ATU components. It’s a fault."

Dick,

I'd like to understand that a bit better. Are you saying that, with a tuning solution that gives 1.6:1, and with that tuning solution being active, that the bypass SWR is being used in the logic that controls the interrupt line?

I would not have expected the bypass SWR to be used in this condition. With the tuner in-line isn't the instantaneous SWR and reflected power what controls the interrupt?

In other words - isn't the bypass SWR only a factor if/when the tuner is bypassed?

Thanks and 73,
Andy, k3wyc
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k4vd

Re: KAT500/KPA500 - Sanity Check Please

In reply to this post by Bob McGraw - K4TAX

Hi Bob:

I'm using a very similar setup and forgot to mention the 1:1 current BALUN.
The 4:1 is outside. There's about 2 feet of coax to a window feedthrough.
Then from the feedthrough to the tuner is the 1:1 BALUN. The antenna is the
80 - 10 from trueladderline.com. Been using this model for years now.

You say "The KAT500 is set to automatically switch to BYPASS if the SWR is
less than 1.3:1. And it is set to bypass the amp if the SWR is greater
than 1.5:1."

Maybe I'm confused with the settings. In the KAT500 configuration under
VSWR thresholds I have:
Band: All
Amp Key Interrupt: 5.00
Autotune: 1.80
Bypass: 1.3

I think this should mean that the amplifier would not be permitted to
operate (key interrupt) if the tuner shows 5:1 or greater SWR. I think it
means that once the *tuned* SWR drops below 5 the amp will be keyed. Should
this be set to 1.5:1? If I really did blow the amp (I'm pretty convinced)
then, over time, this possibly was the contributing factor.

It is my amp that I think has gone bad, not the tuner.

So if the problem were caused because I was regularly running into an
antenna with >10:1 SWR (as noted by bypass SWR on the Operate tab) then I
think the problem would have been with the KAT and not the KPA. Still, I am
surprised there isn't a setting in the configuration tab that would prevent
keying the amp when a certain value of bypass VSWR was exceeded. It could
have a user setting similar to Amplifier Key Interrupt so that, as someone
else mentioned, a person could elect to operate in less than ideal
conditions while a person like me could still have some protection of
pretty expensive equipment.

I still think my amp is bad. Once out of the loop everything works well
barefoot from my rig. The KPA500 tunes just about anything I throw at it
and I'm hoping at 100 watt or less the 12:1 safety limit is not applicable.

"If your showing a Bypass SWR of 12:1 then you are outside of the range of
the KAT500. You are using the wrong balun or you need to change the 600
ohm feed line length to attain a better / lower SWR." Here's where my
misunderstand probably trips me up again. The ladder line fed dipole cut
for 80 meters should be an all-band antenna as long as I can match the load
impedance of the antenna to the radio. For the KAT500, this is a max of
10:1 at 600 watts. For maybe another manufacturer's tuner (auto or manual)
higher specs might be available? Or is there a certain point where the
antenna is just not an antenna? I've got about 10K contacts on this antenna
along with some DXCC and WAS accomplishments. It also seems to do OK in
contests.

The KPA shows the following bypass VSWRs for my antenna:
80 12.00
40 7.46
20 1.63
15 4.61
10 2.33

Changing the BALUN to a different ration would probably shift the numbers
around a bit but not necessarily improve the situation. From these reading,
technically my 80 meter band (for which the antenna is cut) is unusable
with the KAT/KPA at full power but the other bands should be fine. As long
as I fix the setting for the amplifier key interrupt then I should be able
to reduce the risk to the amp on other bands. I have no clue why it was set
to 5.

Thanks for your explanation. It helps a lot.

73,
Kev K4VD

On Sat, Jan 26, 2019 at 10:16 AM Bob McGraw K4TAX <[hidden email]>
wrote:

> My station is a K3S, KPA500, KAT500. The antenna is a 250 ft center
> fed wire with 450 window line that runs from the feed point on the
> antenna all the way to the operating position where the 450 line
> terminates into a 1:1 current balun on the shelf just above the amp and
> tuner. I use a common mode choke between the balun and the KAT500.
> That common mode choke is a model 8232 purchased from The Wireman. It
> is 18" length of coax with about 75 ferrite beads of #43 material.
> This provides additional common mode rejection not offered by the
> balun. I can work 160M through 6M with this configuration.
>
> The KAT500 is set to automatically switch to BYPASS if the SWR is less
> than 1.3:1. And it is set to bypass the amp if the SWR is greater than
> 1.5:1.
>
> A 10:1 SWR basically says the impedance is somewhere between 5 ohms and
> 500 ohms. In order to attain this you will need to use both, depending
> on band a 1:1 balun or a 4:1 balun as likely with your antenna the
> antenna on 40M presents a Z of 3000 ohms or so. Then the length of the
> feed line is critical as it becomes part of the impedance acting as a
> matching length of line. The "600 ohm" impedance of the line is of
> little importance as you are matching the entire complex load and not
> just the impedance of the line. Many hams seem to think, incorrectly,
> they need to match the impedance of the feed line.
>
> If your showing a Bypass SWR of 12:1 then you are outside of the range
> of the KAT500. You are using the wrong balun or you need to change the
> 600 ohm feed line length to attain a better / lower SWR.
>
> The keying line between the KAT500 and KPA500 should interrupt the PTT
> line if the matched SWR exceeds 1.5:1. This is a setting defined in the
> KAT500 configuration by the user and the KAT500 Utility.
>
> The best suggestion, make changes to the antenna such that the SWR
> falls within the range of the tuner. As to the amp, connect a 50 dummy
> load to one output of the tuner {you do have one?} and then see how the
> combination of amp and tuner behave.
>
> I'd say the matching range of the KAT500 is the same at 100 watts. The
> KAT500 manual {page 2} clearly defines the matching ranges and power
> ratings.
>
> 73
>
> Bob, K4TAX
>
>
> On 1/25/2019 10:47 PM, Kevin der Kinderen wrote:
> > I'm reading the specifications for the KAT500. Typical matching range
> from
> > 3-30 MHz is 10:1 SWR for 600 watts.
> >
> > This means that if the KAT500 utility reports "Bypass VSWR" in excess of
> > 10:1 then the KPA500 should not be set to operate.
> >
> > I'm running a dipole cut for 80 and fed with 600 ohm ladder line as a
> > multiband antenna. The BALUN is right outside my window. I have the
> option
> > of 1:1, 4:1, 9:1 and 12:1 I think. They are DXE brand. My job then is to
> > pick the right BALUN to provide <10:1 SWR on the bands of interest. I
> hoped
> > this would be at least 80-20 if not 80-10.
> >
> > Not sure which BALUN is plugged in right now but on 80 meters I'm
> showing a
> > bypass VSWR of 12.00 and VSWR of 1.6:1. This means I cannot use the
> KPA500
> > on 80 regardless of the good match the KAT500 provided.
> >
> > Should the key line cables from the KAT500 to the KPA500 and the rig
> (using
> > a Flex) prevent keying the amp if the SWR exceeds 10:1 automatically?
> >
> > If I want better than that then I have to find another antenna tuner
> with a
> > wider SWR range at 600 watts or a different antenna?
> >
> > Can anyone guess at the matching range of the KAT500 at 100W?
> >
> > The thing is... I think I have a dead amp.
> >
> > Kev K4VD
> > ______________________________________________________________
> > Elecraft mailing list
> > Home: http://mailman.qth.net/mailman/listinfo/elecraft
> > Help: http://mailman.qth.net/mmfaq.htm
> > Post: mailto:[hidden email]
> >
> > This list hosted by: http://www.qsl.net
> > Please help support this email list: http://www.qsl.net/donate.html
> > Message delivered to [hidden email]
> >
>
>

Dick Dievendorff-4

Re: KAT500/KPA500 - Sanity Check Please

In reply to this post by ANDY DURBIN

Andy:

If the RF power is high enough, and the bypass SWR is high enough, the ATU will fault and interrupt the amp key line. I’m away from the code right now, but we named this fault something like “power too high for bypass SWR”.

This is distinct from another SWR-related fault when the matched SWR, as seen by the amp, exceeds a threshold. This is the “amp key interrupt threshold”, and you can set that. Some users want this out of the way, they trust the amp to protect itself, so they set this to 99:1. I think it defaults to 3:1.

There are two SWR-related faults, both interrupt the amp key line. One is based on SWR as seen by the amp. The other is the SWR of the antenna, measured with the ATU bypassed, the bypass SWR, with RF power too high.

If the SWR seen by the amp is low enough, the amp doesn’t care what the bypass SWR is, as the amp doesn't see that SWR.

ATU components have voltage and current ratings that might be exceeded if higher power is permitted with a difficult load. This is why 10:1 bypass SWR can’t be allowed at 1000 watts, even if the SWR seen by the amp is 1.000 to 1.

It is inconvenient (sometimes impossible) and too slow to measure bypass SWR every time a tuning solution is recalled. So this bypass SWR is measured during a full search tune and is retained in the stored ATU setting.

I’m on vacation and we are about to head out, so I’ll need to let this go for a while.

73 de Dick, K6KR

> On Jan 26, 2019, at 11:36, Andy Durbin <[hidden email]> wrote:
>
> "The ATU does interrupt the amp key line when the bypass SWR is too high AND there is enough forward power to endanger ATU components. It’s a fault."
>
>
> Dick,
>
> I'd like to understand that a bit better. Are you saying that, with a tuning solution that gives 1.6:1, and with that tuning solution being active, that the bypass SWR is being used in the logic that controls the interrupt line?
>
> I would not have expected the bypass SWR to be used in this condition. With the tuner in-line isn't the instantaneous SWR and reflected power what controls the interrupt?
>
> In other words - isn't the bypass SWR only a factor if/when the tuner is bypassed?
>
> Thanks and 73,
> Andy, k3wyc
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:[hidden email]
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
> Message delivered to [hidden email]

Elecraft mailing list

Re: KAT500/KPA500 - Sanity Check Please

In reply to this post by k4vd

Kevin;

Why do you think there is a problem with the KPA500? I haven’t seen anything so far that explains that.
In addition to the protections the KAT500 provides, the KPA500 has its own set of protections that keep
it going or place it into a safe state. The KPA can take a lot of abuse before it faults, and it does quite a bit
to keep itself from being damaged.

As someone has suggested (I think it was Bob), you should test the KPA500 into a dummy load to make sure if there is an issue.
If something shows up in that situation, then please do raise the issue with support. If you have questions about the KPA500’s
operation, I should be able not answer them. I suspect your issues are with the setup of the KAT500 and perhaps an understanding
of its protection mechanisms. Answering those questions should do a lot to get you going.

One thing of note - the KPA and the KAT do not communicate with each other. If the Key signal is routed through the KAT to the KPA,
then the KAT will protect the amplifier by disabling the key line into the KPA. Thus it is very important to connect this mechanism (as
you have done).

There is some very good expertise on the reflector. I believe that collectively they will be able to get you going.

By the way, my own setup is similar - the antenna is a 250 foot loop at 35 feet fed with about 15 feet of ladder line. The ladder line connects
to a 1:1balanced to unbalanced transformer (aka balun) that feeds eight feet of RG-213 into the KAT500. It tunes on every HF band
except 160 meters. NEC analysis and real measurements show that the impedance on 160 is way too low for any match.

73!
Jack, W6FB

> On Jan 26, 2019, at 10:22 AM, Kevin der Kinderen <[hidden email]> wrote:
>
> Hi Bob:
>
> I'm using a very similar setup and forgot to mention the 1:1 current BALUN.
> The 4:1 is outside. There's about 2 feet of coax to a window feedthrough.
> Then from the feedthrough to the tuner is the 1:1 BALUN. The antenna is the
> 80 - 10 from trueladderline.com. Been using this model for years now.
>
> You say "The KAT500 is set to automatically switch to BYPASS if the SWR is
> less than 1.3:1. And it is set to bypass the amp if the SWR is greater
> than 1.5:1."
>
> Maybe I'm confused with the settings. In the KAT500 configuration under
> VSWR thresholds I have:
> Band: All
> Amp Key Interrupt: 5.00
> Autotune: 1.80
> Bypass: 1.3
>
> I think this should mean that the amplifier would not be permitted to
> operate (key interrupt) if the tuner shows 5:1 or greater SWR. I think it
> means that once the *tuned* SWR drops below 5 the amp will be keyed. Should
> this be set to 1.5:1? If I really did blow the amp (I'm pretty convinced)
> then, over time, this possibly was the contributing factor.
>
> It is my amp that I think has gone bad, not the tuner.
>
> So if the problem were caused because I was regularly running into an
> antenna with >10:1 SWR (as noted by bypass SWR on the Operate tab) then I
> think the problem would have been with the KAT and not the KPA. Still, I am
> surprised there isn't a setting in the configuration tab that would prevent
> keying the amp when a certain value of bypass VSWR was exceeded. It could
> have a user setting similar to Amplifier Key Interrupt so that, as someone
> else mentioned, a person could elect to operate in less than ideal
> conditions while a person like me could still have some protection of
> pretty expensive equipment.
>
> I still think my amp is bad. Once out of the loop everything works well
> barefoot from my rig. The KPA500 tunes just about anything I throw at it
> and I'm hoping at 100 watt or less the 12:1 safety limit is not applicable.
>
> "If your showing a Bypass SWR of 12:1 then you are outside of the range of
> the KAT500. You are using the wrong balun or you need to change the 600
> ohm feed line length to attain a better / lower SWR." Here's where my
> misunderstand probably trips me up again. The ladder line fed dipole cut
> for 80 meters should be an all-band antenna as long as I can match the load
> impedance of the antenna to the radio. For the KAT500, this is a max of
> 10:1 at 600 watts. For maybe another manufacturer's tuner (auto or manual)
> higher specs might be available? Or is there a certain point where the
> antenna is just not an antenna? I've got about 10K contacts on this antenna
> along with some DXCC and WAS accomplishments. It also seems to do OK in
> contests.
>
> The KPA shows the following bypass VSWRs for my antenna:
> 80 12.00
> 40 7.46
> 20 1.63
> 15 4.61
> 10 2.33
>
> Changing the BALUN to a different ration would probably shift the numbers
> around a bit but not necessarily improve the situation. From these reading,
> technically my 80 meter band (for which the antenna is cut) is unusable
> with the KAT/KPA at full power but the other bands should be fine. As long
> as I fix the setting for the amplifier key interrupt then I should be able
> to reduce the risk to the amp on other bands. I have no clue why it was set
> to 5.
>
> Thanks for your explanation. It helps a lot.
>
> 73,
> Kev K4VD
>
> On Sat, Jan 26, 2019 at 10:16 AM Bob McGraw K4TAX <[hidden email]>
> wrote:
>
>> My station is a K3S, KPA500, KAT500. The antenna is a 250 ft center
>> fed wire with 450 window line that runs from the feed point on the
>> antenna all the way to the operating position where the 450 line
>> terminates into a 1:1 current balun on the shelf just above the amp and
>> tuner. I use a common mode choke between the balun and the KAT500.
>> That common mode choke is a model 8232 purchased from The Wireman. It
>> is 18" length of coax with about 75 ferrite beads of #43 material.
>> This provides additional common mode rejection not offered by the
>> balun. I can work 160M through 6M with this configuration.
>>
>> The KAT500 is set to automatically switch to BYPASS if the SWR is less
>> than 1.3:1. And it is set to bypass the amp if the SWR is greater than
>> 1.5:1.
>>
>> A 10:1 SWR basically says the impedance is somewhere between 5 ohms and
>> 500 ohms. In order to attain this you will need to use both, depending
>> on band a 1:1 balun or a 4:1 balun as likely with your antenna the
>> antenna on 40M presents a Z of 3000 ohms or so. Then the length of the
>> feed line is critical as it becomes part of the impedance acting as a
>> matching length of line. The "600 ohm" impedance of the line is of
>> little importance as you are matching the entire complex load and not
>> just the impedance of the line. Many hams seem to think, incorrectly,
>> they need to match the impedance of the feed line.
>>
>> If your showing a Bypass SWR of 12:1 then you are outside of the range
>> of the KAT500. You are using the wrong balun or you need to change the
>> 600 ohm feed line length to attain a better / lower SWR.
>>
>> The keying line between the KAT500 and KPA500 should interrupt the PTT
>> line if the matched SWR exceeds 1.5:1. This is a setting defined in the
>> KAT500 configuration by the user and the KAT500 Utility.
>>
>> The best suggestion, make changes to the antenna such that the SWR
>> falls within the range of the tuner. As to the amp, connect a 50 dummy
>> load to one output of the tuner {you do have one?} and then see how the
>> combination of amp and tuner behave.
>>
>> I'd say the matching range of the KAT500 is the same at 100 watts. The
>> KAT500 manual {page 2} clearly defines the matching ranges and power
>> ratings.
>>
>> 73
>>
>> Bob, K4TAX
>>
>>
>> On 1/25/2019 10:47 PM, Kevin der Kinderen wrote:
>>> I'm reading the specifications for the KAT500. Typical matching range
>> from
>>> 3-30 MHz is 10:1 SWR for 600 watts.
>>>
>>> This means that if the KAT500 utility reports "Bypass VSWR" in excess of
>>> 10:1 then the KPA500 should not be set to operate.
>>>
>>> I'm running a dipole cut for 80 and fed with 600 ohm ladder line as a
>>> multiband antenna. The BALUN is right outside my window. I have the
>> option
>>> of 1:1, 4:1, 9:1 and 12:1 I think. They are DXE brand. My job then is to
>>> pick the right BALUN to provide <10:1 SWR on the bands of interest. I
>> hoped
>>> this would be at least 80-20 if not 80-10.
>>>
>>> Not sure which BALUN is plugged in right now but on 80 meters I'm
>> showing a
>>> bypass VSWR of 12.00 and VSWR of 1.6:1. This means I cannot use the
>> KPA500
>>> on 80 regardless of the good match the KAT500 provided.
>>>
>>> Should the key line cables from the KAT500 to the KPA500 and the rig
>> (using
>>> a Flex) prevent keying the amp if the SWR exceeds 10:1 automatically?
>>>
>>> If I want better than that then I have to find another antenna tuner
>> with a
>>> wider SWR range at 600 watts or a different antenna?
>>>
>>> Can anyone guess at the matching range of the KAT500 at 100W?
>>>
>>> The thing is... I think I have a dead amp.
>>>
>>> Kev K4VD
>>> ______________________________________________________________
>>> Elecraft mailing list
>>> Home: http://mailman.qth.net/mailman/listinfo/elecraft
>>> Help: http://mailman.qth.net/mmfaq.htm
>>> Post: mailto:[hidden email]
>>>
>>> This list hosted by: http://www.qsl.net
>>> Please help support this email list: http://www.qsl.net/donate.html
>>> Message delivered to [hidden email]
>>>
>>
>>
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:[hidden email]
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
> Message delivered to [hidden email]

ANDY DURBIN

Re: KAT500/KPA500 - Sanity Check Please

In reply to this post by Dick Dievendorff-4

Thanks Dick. Info added to my KAT500 notes.

The fault condition you mentioned appears to be fault code 2 -

"Power Above Design Limit for Antenna SWR - Transmitter power exceeds the design limit for the unmatched antenna SWR. This power limit varies with the SWR of the antenna: 600 watts at 10:1 SWR, 1000 watts at 3:1 SWR."

It would not appear to be applicable for the OP's case since he does not report a fault.

No reply expected - enjoy your vacation.

73,
Andy k3wyc

______________________________________________________________
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k4vd

Re: KAT500/KPA500 - Sanity Check Please

In reply to this post by Elecraft mailing list

Hi Jack... I hope you can prove me wrong and maybe there's a setup issue.

The first symptom is, without the amp in line (standby or simply bypassed
with a cable) everything works.

With the amp in line, sometimes (very rarely) everything works but then all
of a sudden the power out of the amp drops to zero and both the radio and
the KAT show high SWR. This kind of makes me think the KAT500 is the
problem. Why would the KAT500 show high SWR. But...

In the condition mentioned above but now in receive, when I change the amp
from operate to standby the signal strength shown by the receiver changes.
In standby, everything looks normal. But in operate even the noise level
drops significantly. Oddly, it almost looks like other signals have popped
up weakly and distorted (I'm using a Flex so I'm watching the waterfall).
Switching the amp back to standby and everything is back to normal again.
This makes me think the KPA500 is the problem.

Maybe I'm wrong but I can't get anything to fail when the amp is out of the
circuit and can very rarely get anything to work when the amp is in the
circuit. Maybe something to do with the control cables? I'm only using the
PTT relay cables between the KAT500 and the amp and the KAT500 and the Flex
6500 (TX1). I followed Elecraft's "High Power Bundle for the Flex 6500"
document. If there were something going on with this signal I could see it
inhibiting the amp on transmit but on receive?

Kev

On Sat, Jan 26, 2019 at 1:53 PM Jack Brindle <[hidden email]> wrote:

> Kevin;
>
> Why do you think there is a problem with the KPA500? I haven’t seen
> anything so far that explains that.
> In addition to the protections the KAT500 provides, the KPA500 has its own
> set of protections that keep
> it going or place it into a safe state. The KPA can take a lot of abuse
> before it faults, and it does quite a bit
> to keep itself from being damaged.
>
> As someone has suggested (I think it was Bob), you should test the KPA500
> into a dummy load to make sure if there is an issue.
> If something shows up in that situation, then please do raise the issue
> with support. If you have questions about the KPA500’s
> operation, I should be able not answer them. I suspect your issues are
> with the setup of the KAT500 and perhaps an understanding
> of its protection mechanisms. Answering those questions should do a lot to
> get you going.
>
> One thing of note - the KPA and the KAT do not communicate with each
> other. If the Key signal is routed through the KAT to the KPA,
> then the KAT will protect the amplifier by disabling the key line into the
> KPA. Thus it is very important to connect this mechanism (as
> you have done).
>
> There is some very good expertise on the reflector. I believe that
> collectively they will be able to get you going.
>
> By the way, my own setup is similar - the antenna is a 250 foot loop at 35
> feet fed with about 15 feet of ladder line. The ladder line connects
> to a 1:1balanced to unbalanced transformer (aka balun) that feeds eight
> feet of RG-213 into the KAT500. It tunes on every HF band
> except 160 meters. NEC analysis and real measurements show that the
> impedance on 160 is way too low for any match.
>
> 73!
> Jack, W6FB
>
>
>
> > On Jan 26, 2019, at 10:22 AM, Kevin der Kinderen <[hidden email]>
> wrote:
> >
> > Hi Bob:
> >
> > I'm using a very similar setup and forgot to mention the 1:1 current
> BALUN.
> > The 4:1 is outside. There's about 2 feet of coax to a window feedthrough.
> > Then from the feedthrough to the tuner is the 1:1 BALUN. The antenna is
> the
> > 80 - 10 from trueladderline.com. Been using this model for years now.
> >
> > You say "The KAT500 is set to automatically switch to BYPASS if the SWR
> is
> > less than 1.3:1. And it is set to bypass the amp if the SWR is greater
> > than 1.5:1."
> >
> > Maybe I'm confused with the settings. In the KAT500 configuration under
> > VSWR thresholds I have:
> > Band: All
> > Amp Key Interrupt: 5.00
> > Autotune: 1.80
> > Bypass: 1.3
> >
> > I think this should mean that the amplifier would not be permitted to
> > operate (key interrupt) if the tuner shows 5:1 or greater SWR. I think it
> > means that once the *tuned* SWR drops below 5 the amp will be keyed.
> Should
> > this be set to 1.5:1? If I really did blow the amp (I'm pretty convinced)
> > then, over time, this possibly was the contributing factor.
> >
> > It is my amp that I think has gone bad, not the tuner.
> >
> > So if the problem were caused because I was regularly running into an
> > antenna with >10:1 SWR (as noted by bypass SWR on the Operate tab) then I
> > think the problem would have been with the KAT and not the KPA. Still, I
> am
> > surprised there isn't a setting in the configuration tab that would
> prevent
> > keying the amp when a certain value of bypass VSWR was exceeded. It could
> > have a user setting similar to Amplifier Key Interrupt so that, as
> someone
> > else mentioned, a person could elect to operate in less than ideal
> > conditions while a person like me could still have some protection of
> > pretty expensive equipment.
> >
> > I still think my amp is bad. Once out of the loop everything works well
> > barefoot from my rig. The KPA500 tunes just about anything I throw at it
> > and I'm hoping at 100 watt or less the 12:1 safety limit is not
> applicable.
> >
> > "If your showing a Bypass SWR of 12:1 then you are outside of the range
> of
> > the KAT500. You are using the wrong balun or you need to change the 600
> > ohm feed line length to attain a better / lower SWR." Here's where my
> > misunderstand probably trips me up again. The ladder line fed dipole cut
> > for 80 meters should be an all-band antenna as long as I can match the
> load
> > impedance of the antenna to the radio. For the KAT500, this is a max of
> > 10:1 at 600 watts. For maybe another manufacturer's tuner (auto or
> manual)
> > higher specs might be available? Or is there a certain point where the
> > antenna is just not an antenna? I've got about 10K contacts on this
> antenna
> > along with some DXCC and WAS accomplishments. It also seems to do OK in
> > contests.
> >
> > The KPA shows the following bypass VSWRs for my antenna:
> > 80 12.00
> > 40 7.46
> > 20 1.63
> > 15 4.61
> > 10 2.33
> >
> > Changing the BALUN to a different ration would probably shift the numbers
> > around a bit but not necessarily improve the situation. From these
> reading,
> > technically my 80 meter band (for which the antenna is cut) is unusable
> > with the KAT/KPA at full power but the other bands should be fine. As
> long
> > as I fix the setting for the amplifier key interrupt then I should be
> able
> > to reduce the risk to the amp on other bands. I have no clue why it was
> set
> > to 5.
> >
> > Thanks for your explanation. It helps a lot.
> >
> > 73,
> > Kev K4VD
> >
> > On Sat, Jan 26, 2019 at 10:16 AM Bob McGraw K4TAX <[hidden email]>
> > wrote:
> >
> >> My station is a K3S, KPA500, KAT500. The antenna is a 250 ft center
> >> fed wire with 450 window line that runs from the feed point on the
> >> antenna all the way to the operating position where the 450 line
> >> terminates into a 1:1 current balun on the shelf just above the amp and
> >> tuner. I use a common mode choke between the balun and the KAT500.
> >> That common mode choke is a model 8232 purchased from The Wireman. It
> >> is 18" length of coax with about 75 ferrite beads of #43 material.
> >> This provides additional common mode rejection not offered by the
> >> balun. I can work 160M through 6M with this configuration.
> >>
> >> The KAT500 is set to automatically switch to BYPASS if the SWR is less
> >> than 1.3:1. And it is set to bypass the amp if the SWR is greater than
> >> 1.5:1.
> >>
> >> A 10:1 SWR basically says the impedance is somewhere between 5 ohms and
> >> 500 ohms. In order to attain this you will need to use both, depending
> >> on band a 1:1 balun or a 4:1 balun as likely with your antenna the
> >> antenna on 40M presents a Z of 3000 ohms or so. Then the length of the
> >> feed line is critical as it becomes part of the impedance acting as a
> >> matching length of line. The "600 ohm" impedance of the line is of
> >> little importance as you are matching the entire complex load and not
> >> just the impedance of the line. Many hams seem to think, incorrectly,
> >> they need to match the impedance of the feed line.
> >>
> >> If your showing a Bypass SWR of 12:1 then you are outside of the range
> >> of the KAT500. You are using the wrong balun or you need to change the
> >> 600 ohm feed line length to attain a better / lower SWR.
> >>
> >> The keying line between the KAT500 and KPA500 should interrupt the PTT
> >> line if the matched SWR exceeds 1.5:1. This is a setting defined in the
> >> KAT500 configuration by the user and the KAT500 Utility.
> >>
> >> The best suggestion, make changes to the antenna such that the SWR
> >> falls within the range of the tuner. As to the amp, connect a 50 dummy
> >> load to one output of the tuner {you do have one?} and then see how the
> >> combination of amp and tuner behave.
> >>
> >> I'd say the matching range of the KAT500 is the same at 100 watts. The
> >> KAT500 manual {page 2} clearly defines the matching ranges and power
> >> ratings.
> >>
> >> 73
> >>
> >> Bob, K4TAX
> >>
> >>
> >> On 1/25/2019 10:47 PM, Kevin der Kinderen wrote:
> >>> I'm reading the specifications for the KAT500. Typical matching range
> >> from
> >>> 3-30 MHz is 10:1 SWR for 600 watts.
> >>>
> >>> This means that if the KAT500 utility reports "Bypass VSWR" in excess
> of
> >>> 10:1 then the KPA500 should not be set to operate.
> >>>
> >>> I'm running a dipole cut for 80 and fed with 600 ohm ladder line as a
> >>> multiband antenna. The BALUN is right outside my window. I have the
> >> option
> >>> of 1:1, 4:1, 9:1 and 12:1 I think. They are DXE brand. My job then is
> to
> >>> pick the right BALUN to provide <10:1 SWR on the bands of interest. I
> >> hoped
> >>> this would be at least 80-20 if not 80-10.
> >>>
> >>> Not sure which BALUN is plugged in right now but on 80 meters I'm
> >> showing a
> >>> bypass VSWR of 12.00 and VSWR of 1.6:1. This means I cannot use the
> >> KPA500
> >>> on 80 regardless of the good match the KAT500 provided.
> >>>
> >>> Should the key line cables from the KAT500 to the KPA500 and the rig
> >> (using
> >>> a Flex) prevent keying the amp if the SWR exceeds 10:1 automatically?
> >>>
> >>> If I want better than that then I have to find another antenna tuner
> >> with a
> >>> wider SWR range at 600 watts or a different antenna?
> >>>
> >>> Can anyone guess at the matching range of the KAT500 at 100W?
> >>>
> >>> The thing is... I think I have a dead amp.
> >>>
> >>> Kev K4VD
> >>> ______________________________________________________________
> >>> Elecraft mailing list
> >>> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> >>> Help: http://mailman.qth.net/mmfaq.htm
> >>> Post: mailto:[hidden email]
> >>>
> >>> This list hosted by: http://www.qsl.net
> >>> Please help support this email list: http://www.qsl.net/donate.html
> >>> Message delivered to [hidden email]
> >>>
> >>
> >>
> > ______________________________________________________________
> > Elecraft mailing list
> > Home: http://mailman.qth.net/mailman/listinfo/elecraft
> > Help: http://mailman.qth.net/mmfaq.htm
> > Post: mailto:[hidden email]
> >
> > This list hosted by: http://www.qsl.net
> > Please help support this email list: http://www.qsl.net/donate.html
> > Message delivered to [hidden email]
>
>

Elecraft mailing list

Re: KAT500/KPA500 - Sanity Check Please

You may be right on the KPA. This sounds like a TR issue. Call tech support on Monday and discuss it with them.
In the mean time, I may be able to help further the diagnosis - use the KPA Utility to gather a fault log and send it to me.
I have tools that will parse the info and let me know of any catastrophic events that may have occurred.

One other item for your understanding - the KPA almost exclusively looks at reflected power, not SWR for its
protection. That means the KPA can withstand relatively high SWR at low power, but as output power increases the
actual SWR must come down. As K6KR has explained, The KAT500 does look at SWR, and the amount of bypass SWR
that the KAT can handle increases as power drops. This is to protect the KAT500’s LC and switching components at higher power.
Thus the max SWR is lower at 1000 watts than at 100 watts.

I was hoping you were incorrect about the KPA500 issue. Your description tells me otherwise. Let’s see what we can do to resolve the issue
and get some more countries (and contest QSOs with me among others) in your log.

73!
Jack, W6FB

> On Jan 26, 2019, at 11:10 AM, Kevin der Kinderen <[hidden email]> wrote:
>
> Hi Jack... I hope you can prove me wrong and maybe there's a setup issue.
>
> The first symptom is, without the amp in line (standby or simply bypassed with a cable) everything works.
>
> With the amp in line, sometimes (very rarely) everything works but then all of a sudden the power out of the amp drops to zero and both the radio and the KAT show high SWR. This kind of makes me think the KAT500 is the problem. Why would the KAT500 show high SWR. But...
>
> In the condition mentioned above but now in receive, when I change the amp from operate to standby the signal strength shown by the receiver changes. In standby, everything looks normal. But in operate even the noise level drops significantly. Oddly, it almost looks like other signals have popped up weakly and distorted (I'm using a Flex so I'm watching the waterfall). Switching the amp back to standby and everything is back to normal again. This makes me think the KPA500 is the problem.
>
> Maybe I'm wrong but I can't get anything to fail when the amp is out of the circuit and can very rarely get anything to work when the amp is in the circuit. Maybe something to do with the control cables? I'm only using the PTT relay cables between the KAT500 and the amp and the KAT500 and the Flex 6500 (TX1). I followed Elecraft's "High Power Bundle for the Flex 6500" document. If there were something going on with this signal I could see it inhibiting the amp on transmit but on receive?
>
> Kev
>
>
> On Sat, Jan 26, 2019 at 1:53 PM Jack Brindle <[hidden email] <mailto:[hidden email]>> wrote:
> Kevin;
>
> Why do you think there is a problem with the KPA500? I haven’t seen anything so far that explains that.
> In addition to the protections the KAT500 provides, the KPA500 has its own set of protections that keep
> it going or place it into a safe state. The KPA can take a lot of abuse before it faults, and it does quite a bit
> to keep itself from being damaged.
>
> As someone has suggested (I think it was Bob), you should test the KPA500 into a dummy load to make sure if there is an issue.
> If something shows up in that situation, then please do raise the issue with support. If you have questions about the KPA500’s
> operation, I should be able not answer them. I suspect your issues are with the setup of the KAT500 and perhaps an understanding
> of its protection mechanisms. Answering those questions should do a lot to get you going.
>
> One thing of note - the KPA and the KAT do not communicate with each other. If the Key signal is routed through the KAT to the KPA,
> then the KAT will protect the amplifier by disabling the key line into the KPA. Thus it is very important to connect this mechanism (as
> you have done).
>
> There is some very good expertise on the reflector. I believe that collectively they will be able to get you going.
>
> By the way, my own setup is similar - the antenna is a 250 foot loop at 35 feet fed with about 15 feet of ladder line. The ladder line connects
> to a 1:1balanced to unbalanced transformer (aka balun) that feeds eight feet of RG-213 into the KAT500. It tunes on every HF band
> except 160 meters. NEC analysis and real measurements show that the impedance on 160 is way too low for any match.
>
> 73!
> Jack, W6FB
>
>
>
> > On Jan 26, 2019, at 10:22 AM, Kevin der Kinderen <[hidden email] <mailto:[hidden email]>> wrote:
> >
> > Hi Bob:
> >
> > I'm using a very similar setup and forgot to mention the 1:1 current BALUN.
> > The 4:1 is outside. There's about 2 feet of coax to a window feedthrough.
> > Then from the feedthrough to the tuner is the 1:1 BALUN. The antenna is the
> > 80 - 10 from trueladderline.com <http://trueladderline.com/>. Been using this model for years now.
> >
> > You say "The KAT500 is set to automatically switch to BYPASS if the SWR is
> > less than 1.3:1. And it is set to bypass the amp if the SWR is greater
> > than 1.5:1."
> >
> > Maybe I'm confused with the settings. In the KAT500 configuration under
> > VSWR thresholds I have:
> > Band: All
> > Amp Key Interrupt: 5.00
> > Autotune: 1.80
> > Bypass: 1.3
> >
> > I think this should mean that the amplifier would not be permitted to
> > operate (key interrupt) if the tuner shows 5:1 or greater SWR. I think it
> > means that once the *tuned* SWR drops below 5 the amp will be keyed. Should
> > this be set to 1.5:1? If I really did blow the amp (I'm pretty convinced)
> > then, over time, this possibly was the contributing factor.
> >
> > It is my amp that I think has gone bad, not the tuner.
> >
> > So if the problem were caused because I was regularly running into an
> > antenna with >10:1 SWR (as noted by bypass SWR on the Operate tab) then I
> > think the problem would have been with the KAT and not the KPA. Still, I am
> > surprised there isn't a setting in the configuration tab that would prevent
> > keying the amp when a certain value of bypass VSWR was exceeded. It could
> > have a user setting similar to Amplifier Key Interrupt so that, as someone
> > else mentioned, a person could elect to operate in less than ideal
> > conditions while a person like me could still have some protection of
> > pretty expensive equipment.
> >
> > I still think my amp is bad. Once out of the loop everything works well
> > barefoot from my rig. The KPA500 tunes just about anything I throw at it
> > and I'm hoping at 100 watt or less the 12:1 safety limit is not applicable.
> >
> > "If your showing a Bypass SWR of 12:1 then you are outside of the range of
> > the KAT500. You are using the wrong balun or you need to change the 600
> > ohm feed line length to attain a better / lower SWR." Here's where my
> > misunderstand probably trips me up again. The ladder line fed dipole cut
> > for 80 meters should be an all-band antenna as long as I can match the load
> > impedance of the antenna to the radio. For the KAT500, this is a max of
> > 10:1 at 600 watts. For maybe another manufacturer's tuner (auto or manual)
> > higher specs might be available? Or is there a certain point where the
> > antenna is just not an antenna? I've got about 10K contacts on this antenna
> > along with some DXCC and WAS accomplishments. It also seems to do OK in
> > contests.
> >
> > The KPA shows the following bypass VSWRs for my antenna:
> > 80 12.00
> > 40 7.46
> > 20 1.63
> > 15 4.61
> > 10 2.33
> >
> > Changing the BALUN to a different ration would probably shift the numbers
> > around a bit but not necessarily improve the situation. From these reading,
> > technically my 80 meter band (for which the antenna is cut) is unusable
> > with the KAT/KPA at full power but the other bands should be fine. As long
> > as I fix the setting for the amplifier key interrupt then I should be able
> > to reduce the risk to the amp on other bands. I have no clue why it was set
> > to 5.
> >
> > Thanks for your explanation. It helps a lot.
> >
> > 73,
> > Kev K4VD
> >
> > On Sat, Jan 26, 2019 at 10:16 AM Bob McGraw K4TAX <[hidden email] <mailto:[hidden email]>>
> > wrote:
> >
> >> My station is a K3S, KPA500, KAT500. The antenna is a 250 ft center
> >> fed wire with 450 window line that runs from the feed point on the
> >> antenna all the way to the operating position where the 450 line
> >> terminates into a 1:1 current balun on the shelf just above the amp and
> >> tuner. I use a common mode choke between the balun and the KAT500.
> >> That common mode choke is a model 8232 purchased from The Wireman. It
> >> is 18" length of coax with about 75 ferrite beads of #43 material.
> >> This provides additional common mode rejection not offered by the
> >> balun. I can work 160M through 6M with this configuration.
> >>
> >> The KAT500 is set to automatically switch to BYPASS if the SWR is less
> >> than 1.3:1. And it is set to bypass the amp if the SWR is greater than
> >> 1.5:1.
> >>
> >> A 10:1 SWR basically says the impedance is somewhere between 5 ohms and
> >> 500 ohms. In order to attain this you will need to use both, depending
> >> on band a 1:1 balun or a 4:1 balun as likely with your antenna the
> >> antenna on 40M presents a Z of 3000 ohms or so. Then the length of the
> >> feed line is critical as it becomes part of the impedance acting as a
> >> matching length of line. The "600 ohm" impedance of the line is of
> >> little importance as you are matching the entire complex load and not
> >> just the impedance of the line. Many hams seem to think, incorrectly,
> >> they need to match the impedance of the feed line.
> >>
> >> If your showing a Bypass SWR of 12:1 then you are outside of the range
> >> of the KAT500. You are using the wrong balun or you need to change the
> >> 600 ohm feed line length to attain a better / lower SWR.
> >>
> >> The keying line between the KAT500 and KPA500 should interrupt the PTT
> >> line if the matched SWR exceeds 1.5:1. This is a setting defined in the
> >> KAT500 configuration by the user and the KAT500 Utility.
> >>
> >> The best suggestion, make changes to the antenna such that the SWR
> >> falls within the range of the tuner. As to the amp, connect a 50 dummy
> >> load to one output of the tuner {you do have one?} and then see how the
> >> combination of amp and tuner behave.
> >>
> >> I'd say the matching range of the KAT500 is the same at 100 watts. The
> >> KAT500 manual {page 2} clearly defines the matching ranges and power
> >> ratings.
> >>
> >> 73
> >>
> >> Bob, K4TAX
> >>
> >>
> >> On 1/25/2019 10:47 PM, Kevin der Kinderen wrote:
> >>> I'm reading the specifications for the KAT500. Typical matching range
> >> from
> >>> 3-30 MHz is 10:1 SWR for 600 watts.
> >>>
> >>> This means that if the KAT500 utility reports "Bypass VSWR" in excess of
> >>> 10:1 then the KPA500 should not be set to operate.
> >>>
> >>> I'm running a dipole cut for 80 and fed with 600 ohm ladder line as a
> >>> multiband antenna. The BALUN is right outside my window. I have the
> >> option
> >>> of 1:1, 4:1, 9:1 and 12:1 I think. They are DXE brand. My job then is to
> >>> pick the right BALUN to provide <10:1 SWR on the bands of interest. I
> >> hoped
> >>> this would be at least 80-20 if not 80-10.
> >>>
> >>> Not sure which BALUN is plugged in right now but on 80 meters I'm
> >> showing a
> >>> bypass VSWR of 12.00 and VSWR of 1.6:1. This means I cannot use the
> >> KPA500
> >>> on 80 regardless of the good match the KAT500 provided.
> >>>
> >>> Should the key line cables from the KAT500 to the KPA500 and the rig
> >> (using
> >>> a Flex) prevent keying the amp if the SWR exceeds 10:1 automatically?
> >>>
> >>> If I want better than that then I have to find another antenna tuner
> >> with a
> >>> wider SWR range at 600 watts or a different antenna?
> >>>
> >>> Can anyone guess at the matching range of the KAT500 at 100W?
> >>>
> >>> The thing is... I think I have a dead amp.
> >>>
> >>> Kev K4VD
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