KPA500 installtion with ICOM 7300

I concur that the RF sense works very well, at least it does with an
external antenna switch and reasonably good antenna SWR.  I am not sure
what happens if you also use the KAT500 as an antenna switch or your
untuned SWR is very bad.  Does the amp fault during this first dit?

John KK9A


Jim Brown K9YC wrote:

FWIW, I've never used band data with my KPA500, only the AMP KEY cable.
The KPA500 (and KAT500) are VERY good (and fast) at detecting RF and
changing bands. All it takes is a dit or a tap on the mic.

73, Jim K9YC

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[Don Wilhelm]

John,

The amp is bypassed if the KAT500 needs do do any tuning or switching,
so I suspect the amp will not fault.

That is why you run the keying line first to the KAT500 and then from
the KAT500 to the KPA500, so the tuner can disable the amp.

73,
Don W3FPR

On 5/10/2018 9:31 AM, [hidden email] wrote:
> I concur that the RF sense works very well, at least it does with an
> external antenna switch and reasonably good antenna SWR.  I am not sure
> what happens if you also use the KAT500 as an antenna switch or your
> untuned SWR is very bad.  Does the amp fault during this first dit?
>
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[Jack Brindle-2]

Don is correct (as usual). The KPA will first see the band change, perform that task, then try to amplify at the desired frequency. If it then sees a bad reflected power level it will wait for the KAT to do something (which means removing PTT, then performing its own correction, then re-enabling PTT). If it still sees a bad reflected power level (perhaps there is no KAT), then it will start the remediation process which may end in a fault.

Note that the KPA500 watches reflected power, not SWR (unless SWR is _really_ high). This means that at full output it will object to SWR over about 2:1, while at lower power (say 300 watts), it will allow a higher SWR. Reflected power over about 50 or 60 watts is where it starts the remediation process.That process includes inserting attenuation at the front end (which should also lower the reflected power level) and ultimately in a fault if the attenuation doesn’t do its task or the reflected power is deemed way to high to handle.

So the real answer is that unless you send CW extremely slowly, the KPA500 will perform the band switch and continue monitoring the signal during that first dit, but you probably will not see anything like a fault until many characters down the QSO.

Enjoy the KPA500!

73,
Jack, W6FB

> On May 10, 2018, at 7:20 AM, Don Wilhelm <[hidden email]> wrote:
>
> John,
>
> The amp is bypassed if the KAT500 needs do do any tuning or switching, so I suspect the amp will not fault.
>
> That is why you run the keying line first to the KAT500 and then from the KAT500 to the KPA500, so the tuner can disable the amp.
>
> 73,
> Don W3FPR
>
> On 5/10/2018 9:31 AM, [hidden email] wrote:
>> I concur that the RF sense works very well, at least it does with an
>> external antenna switch and reasonably good antenna SWR.  I am not sure
>> what happens if you also use the KAT500 as an antenna switch or your
>> untuned SWR is very bad.  Does the amp fault during this first dit?
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[ANDY DURBIN]

"That's the point. The ALC cable protects the KPA-500 when the operator "spaces" and leaves the exciter power control at full power (100+ Watt) level."

My experience, and I have 10 Hz logger data, shows that the amp alarms, sets fault FL06, and drops into standby mode with no change in the ALC voltage level being observed.

I didn't set out to investigate this but my logger was running when I accidentally tripped FL06 on 6 meters this afternoon.

It appears to me that ALC only provides protection if the normal over-drive protections fail.  Currently the ALC voltage only feeds my logger and is not connected to my TS-590S.

73, Andy k3wyc




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[Don Wilhelm]

Andy,

If you do connect the ALC, check the maximum drive power that you need
for each band and do not exceed it.  In other words, do not drive the
amp into ALC.

Using ALC to control the transceiver drive power will result in
overdrive and distortion.  You can hear that distortion on the bands.

Should you upgrade to an Elecraft K3, you can set a per band drive level
for when the amplifier is active and when it is bypassed.

73,
Don W3FPR

On 5/10/2018 5:17 PM, ANDY DURBIN wrote:

> "That's the point. The ALC cable protects the KPA-500 when the operator "spaces" and leaves the exciter power control at full power (100+ Watt) level."
>
> My experience, and I have 10 Hz logger data, shows that the amp alarms, sets fault FL06, and drops into standby mode with no change in the ALC voltage level being observed.
>
> I didn't set out to investigate this but my logger was running when I accidentally tripped FL06 on 6 meters this afternoon.
>
> It appears to me that ALC only provides protection if the normal over-drive protections fail.  Currently the ALC voltage only feeds my logger and is not connected to my TS-590S.
>
> 73, Andy k3wyc
>
>
>
>
> ______________________________________________________________
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>

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