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KPA500 STBY to OPER

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ANDY DURBIN

KPA500 STBY to OPER

"With my K3S, when I switch the KPA500 to Operate, the transceiver is automatically reduced to the correct power to drive the amp."

Bob,

I'm curious to know how well that feature works. Let's say your KPA500 is STBY, your K3 is set to 100 W out, and you are transmitting in a digital mode. What happens when you switch the KPA500 to OPER?

If you don't know the answer please don't it!

My controller ensures that the KAT500 key line is inhibited when the KPA500 is in STBY. When the KPA500 goes to OPER I set appropriate exciter power, and only when correct power has been verified do I enable the key line. If I'm transmitting at 100W with KPA500 in STBY then selecting OPER gives a brief power reduction before establishing high power output.

73,
Andy k3wyc
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Re: KPA500 STBY to OPER

Andy;

It works very well. The op has to set the K3 so that the power is controller per-band. When the KPA is switched to OPmode, it sends a message to the K3. The K3 then switches to the amplifier selection for power, which the op has et specifically for the KPA. The converse is also true, switching the KPA to STBY also sends a message that causes the K3 to realize the KPA’s state and move back to its main power setting for the band.

Note that the power level is set for each band for both normal and KPA drive levels. This is well documented in the KPA manual and also in the K3 manual(s).

73!
Jack, W6FB

> On Sep 2, 2019, at 6:58 AM, Andy Durbin <[hidden email]> wrote:
>
> "With my K3S, when I switch the KPA500 to Operate, the transceiver is automatically reduced to the correct power to drive the amp."
>
> Bob,
>
> I'm curious to know how well that feature works. Let's say your KPA500 is STBY, your K3 is set to 100 W out, and you are transmitting in a digital mode. What happens when you switch the KPA500 to OPER?
>
> If you don't know the answer please don't it!
>
> My controller ensures that the KAT500 key line is inhibited when the KPA500 is in STBY. When the KPA500 goes to OPER I set appropriate exciter power, and only when correct power has been verified do I enable the key line. If I'm transmitting at 100W with KPA500 in STBY then selecting OPER gives a brief power reduction before establishing high power output.
>
> 73,
> Andy k3wyc
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
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> Please help support this email list: http://www.qsl.net/donate.html
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Bob McGraw - K4TAX

Re: KPA500 STBY to OPER

In reply to this post by ANDY DURBIN

Andy et al:

With the station configured as shown in the KAT500 manual, page 5 Figure
1, when operating a digital mode or any mode for that matter, and the
amp is in STBY the K3S is delivering the power as set by the PWR
control.    Normally 100 watts.   When the KPA500 is then switched to
OPER the PWR on the K3S is set to the value as defined in the PWR SET
menu.    Typically 20 watts drives the KPA500 to 400 to 500 watts
output.   Thus there are 2 sets of per band power settings, one for
barefoot operation and one for use with the amp.

As to how well it works, I'd say 100% as I have observed no
mis-operation or fault indication in the 2 years of using the station on
a daily basis.

73

Bob, K4TAX

On 9/2/2019 8:58 AM, Andy Durbin wrote:

> "With my K3S, when I switch the KPA500 to Operate, the transceiver is automatically reduced to the correct power to drive the amp."
>
> Bob,
>
> I'm curious to know how well that feature works. Let's say your KPA500 is STBY, your K3 is set to 100 W out, and you are transmitting in a digital mode. What happens when you switch the KPA500 to OPER?
>
> If you don't know the answer please don't it!
>
> My controller ensures that the KAT500 key line is inhibited when the KPA500 is in STBY. When the KPA500 goes to OPER I set appropriate exciter power, and only when correct power has been verified do I enable the key line. If I'm transmitting at 100W with KPA500 in STBY then selecting OPER gives a brief power reduction before establishing high power output.
>
> 73,
> Andy k3wyc

ANDY DURBIN

Re: KPA500 STBY to OPER

In reply to this post by Elecraft mailing list

"It works very well. The op has to set the K3 so that the power is controller per-band. When the KPA is switched to OPmode, it sends a message to the K3. The K3 then switches to the amplifier selection for power, which the op has set specifically for the KPA."

Jack,

I'd love to see the worst case system timing diagram for that but I know that's not likely. Either the [KPA500 state]>[K3]>[K3 power control] is very fast or the KPA500 does not fault as fast as I though it did. Perhaps both?

So, no KPA500 fault, no power spike, and no damage when KPA500 is switched to OPER when K3 is transmitting with 100 W output. I'll have to move that one to the "good as" list from the "better than" list if I even do a write up on my TS-590/Elecraft controller. "Good as Integrated K3/KAT500/KPA500" was a top level system requirement. "Better than" was just nice to have.

73,
Andy, k3wyc

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Rick WA6NHC-2

Re: KPA500 STBY to OPER

In reply to this post by ANDY DURBIN

This feature works VERY well, with the occasional hiccup that the power
isn't lowered, causing a fault (rare, likely not enough time for the
signals to pass between the boxes).

I *DO* suggest that you also set up the amp input/output for *ALL*
bands, in particular the bands where the power limits are much lower
(60M for example, 100 watts ERP compared to a dipole) so if you fail to
recall as you change bands, you don't accidentally exceed limits with
the amp in operate mode.

Rick NHC

On 9/2/2019 7:36 AM, Jack Brindle via Elecraft wrote:

> Andy;
>
> It works very well. The op has to set the K3 so that the power is controller per-band. When the KPA is switched to OPmode, it sends a message to the K3. The K3 then switches to the amplifier selection for power, which the op has et specifically for the KPA. The converse is also true, switching the KPA to STBY also sends a message that causes the K3 to realize the KPA’s state and move back to its main power setting for the band.
>
> Note that the power level is set for each band for both normal and KPA drive levels. This is well documented in the KPA manual and also in the K3 manual(s).
>
> 73!
> Jack, W6FB
>
>
>> On Sep 2, 2019, at 6:58 AM, Andy Durbin<[hidden email]> wrote:
>>
>> "With my K3S, when I switch the KPA500 to Operate, the transceiver is automatically reduced to the correct power to drive the amp."
>>
>> Bob,
>>
>> I'm curious to know how well that feature works. Let's say your KPA500 is STBY, your K3 is set to 100 W out, and you are transmitting in a digital mode. What happens when you switch the KPA500 to OPER?
>>
>> If you don't know the answer please don't it!
>>
>> My controller ensures that the KAT500 key line is inhibited when the KPA500 is in STBY. When the KPA500 goes to OPER I set appropriate exciter power, and only when correct power has been verified do I enable the key line. If I'm transmitting at 100W with KPA500 in STBY then selecting OPER gives a brief power reduction before establishing high power output.
>>
>> 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 [hidden email]
> ______________________________________________________________
> Elecraft mailing list
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>
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Rick WA6NHC-2

Re: KPA500 STBY to OPER

In reply to this post by Bob McGraw - K4TAX

Close but no.

With the amp in standby, the power out up to 100 W is determined by the
power setting (knob) on the K3.

With the amp in operate, the (reduced drive) power is determined by the
power setting on the K3; best if the 'Set by band' feature is used (the
amount of drive for the desired output varies according to the band in use).

You use the _same_ knob for operate/standby, it remembers. It can't be
simpler.

Rick NHC

On 9/2/2019 7:45 AM, Bob McGraw K4TAX wrote:

> Andy et al:
>
> With the station configured as shown in the KAT500 manual, page 5
> Figure 1, when operating a digital mode or any mode for that matter,
> and the amp is in STBY the K3S is delivering the power as set by the
> PWR control.    Normally 100 watts.   When the KPA500 is then switched
> to OPER the PWR on the K3S is set to the value as defined in the PWR
> SET menu.    Typically 20 watts drives the KPA500 to 400 to 500 watts
> output.   Thus there are 2 sets of per band power settings, one for
> barefoot operation and one for use with the amp.
>
> As to how well it works, I'd say 100% as I have observed no
> mis-operation or fault indication in the 2 years of using the station
> on a daily basis.
>
> 73
>
> Bob, K4TAX
>
> On 9/2/2019 8:58 AM, Andy Durbin wrote:
>> "With my K3S, when I switch the KPA500 to Operate, the transceiver is
>> automatically reduced to the correct power to drive the amp."
>>
>> Bob,
>>
>> I'm curious to know how well that feature works. Let's say your
>> KPA500 is STBY, your K3 is set to 100 W out, and you are transmitting
>> in a digital mode. What happens when you switch the KPA500 to OPER?
>>
>> If you don't know the answer please don't it!
>>
>> My controller ensures that the KAT500 key line is inhibited when the
>> KPA500 is in STBY. When the KPA500 goes to OPER I set appropriate
>> exciter power, and only when correct power has been verified do I
>> enable the key line. If I'm transmitting at 100W with KPA500 in STBY
>> then selecting OPER gives a brief power reduction before establishing
>> high power output.
>>
>> 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
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Elecraft mailing list

Re: KPA500 STBY to OPER

In reply to this post by ANDY DURBIN

Maybe to the “Not quite as good as…” category. The issue is timing. Your code has to poll to determine the KPA op state, then start all the transitions which will result in the PTT line being negated. There are a lot of delays involved here.

With the K3/KPA, the button press causes the KPA to send the mode change data to the K3 immediately. We wait until the data transfer is complete before starting the actual mode transition. By the time it is done and the KPA is ready to go, the K3 has processed the message and switched to the alternate (KPA) power level. By the time the K3 has displayed the KPA mode change on its display it has already made the change internally.

Now realistically will anyone see a difference between the two methods? Probably not. The only real way to tell would be to start sending a CW message then tap the mode button to move the KPA to OP mode during the transition. Both methods will pick up the change, but the built-in method will do it slightly faster because of its advantage with not having to poll for the mode state change over the serial port.

Nice job with the controller, by the way. I look forward to your write-up.

73!
Jack, W6FB

> On Sep 2, 2019, at 9:46 AM, Andy Durbin <[hidden email]> wrote:
>
> "It works very well. The op has to set the K3 so that the power is controller per-band. When the KPA is switched to OPmode, it sends a message to the K3. The K3 then switches to the amplifier selection for power, which the op has set specifically for the KPA."
>
> Jack,
>
> I'd love to see the worst case system timing diagram for that but I know that's not likely. Either the [KPA500 state]>[K3]>[K3 power control] is very fast or the KPA500 does not fault as fast as I though it did. Perhaps both?
>
> So, no KPA500 fault, no power spike, and no damage when KPA500 is switched to OPER when K3 is transmitting with 100 W output. I'll have to move that one to the "good as" list from the "better than" list if I even do a write up on my TS-590/Elecraft controller. "Good as Integrated K3/KAT500/KPA500" was a top level system requirement. "Better than" was just nice to have.
>
> 73,
> Andy, k3wyc
>
>
>
>
>
>
>
>

ANDY DURBIN

Re: KPA500 STBY to OPER

"The issue is timing. Your code has to poll to determine the KPA op state, then start all the transitions which will result in the PTT line being negated."

No, not true. There is no timing issue with my implementation since the key line is ALWAYS inhibited while KPA500 is in STBY mode. Required conditions have to be met before the key line is enabled. Any delay due to my slow system interfaces simply means that it takes a bit longer for the KPA500 to be set to OPER power level.

Thanks for the explanation of the KPA500 K3 power control interface.

The driver for doing a write up of my controller will probably be my club's presentations manager. He has twisted my arm a few times to prepare and give presentations and I'm probably due for another turn in the barrel.

73,
Andy, k3wyc

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