[Elecraft] Powering on/off a KPA500. Was: Re: Elecraft Digest, Vol 266, Issue 17

[Jack Brindle]

Please tell us ho you have the K3, KPA500 and KAT500 connected. I have to assume there is a computer in the mix. The K3 cannot talk to the KPA500 to tell is to shut off, nor can it cause the KPA500 to power up. The same is true for the KAT500, although the KAT can power up on its own when power is applied. A computer or other “intelligent” device is needed to tell the KPA and KAT to power up. In the case of the KPA500, there are two ways to remotely power it up - one is to momentarily ground the power line in the AUX IO connector. This signal cannot be tied to the K3’s power signal because of differences in voltage levels. Connecting them will probably be a good reason to send the KPA back for repairs. The second method is to send a “P” (just the P, no quotes needed) to the KPA500 when it is off (using the serial port). After it powers up, you can shut it off by sending the “^ON;” command to the KPA500. See the KAT500 serial command reference for info on commands specific to it.

And again, the K3 does not send data to the KPA500. The Auxbus is strictly send-only from the KPA500. The only signals that go from the K3 to the KPA are the band signals and PTT.

Note that the KPA1500 and KPA500 communicate differently - I don’t have an answer for Jim on his situation.

Second, please trim your list emails when replying to digests, and follow the request to change the subject line. It cuts down on the amount of stuff we have to look through, and tells us which of the message you are replying to.

73,
Jack W6FB

> On Jun 27, 2026, at 12:00 PM, Joseph Koester via Elecraft <elecraft at mailman.qth.net> wrote:
> 
> I have a similar issue with my K3 and my KPA500. I cannot turn the amp off.
> I can turn the tuner off but not the amplifier.
> 
> Joe/W4NSA
> 
> On Sat, Jun 27, 2026, 11:01 <elecraft-request at mailman.qth.net> wrote:
> 
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>> Today's Topics:
>> 
>>   1. K4/KPA500 macro question (Jim Rhodes)
>>   2. KX3 Passband, Pitch, and APF (paul somlo)
>> 
>> 
>> ----------------------------------------------------------------------
>> 
>> Message: 1
>> Date: Sat, 27 Jun 2026 00:17:07 -0500
>> From: Jim Rhodes <jimk0xu at gmail.com>
>> To: elecraft at mailman.qth.net
>> Subject: [Elecraft] K4/KPA500 macro question
>> Message-ID:
>>        <CALhxr4ZyaBLACkEM_3O-1iwJyWgW+wgJWKEWWpQDrFbZMQLz=
>> w at mail.gmail.com>
>> Content-Type: text/plain; charset="UTF-8"
>> 
>> I am trying to set up macros to turn the KPA500 on and off.  I seem to have
>> them entered correctly in the K4D and in the KPA500 app.  But the app will
>> turn the amp on but not off.  The K4 will turn it off but not on.  Object
>> is to get it set up for use with the K4/0.  Does anyone how I messed those
>> up?
>> 
>> Jim K0XU
>> jim at rhodesend.net
>> 
>> 
>> ------------------------------
>> 
>> Message: 2
>> Date: Sat, 27 Jun 2026 05:30:12 +0000 (UTC)
>> From: paul somlo <paul_somlo at yahoo.com>
>> To: "Elecraft at mailman.qth.net" <Elecraft at mailman.qth.net>
>> Subject: [Elecraft] KX3 Passband, Pitch, and APF
>> Message-ID: <1918090948.2521499.1782538212184 at mail.yahoo.com>
>> Content-Type: text/plain; charset=UTF-8
>> 
>> When I turn on "pitch", does the passband coincide with the signal being
>> centered between right and left?? And does the audio peaking filter
>> passband coincide with the regular passband?
>> Paulwb2eiu
>> 
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>> End of Elecraft Digest, Vol 266, Issue 17
>> *****************************************
>> 
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