KPA500 Default Band?

[Jim Bennett]

I have my KPA500 and KAT500 on a switch that can be set to either a K3 or a KX3. The KX3 is new (to me) and I've been using it almost exclusively since assembling this fine Christmas present. Recently I've noticed a strange behavior and am wondering if this is due to a recent firmware change or if I've simply never noticed it before. In either case, it there a way to stop it from happening? Here's the situation -

Let's say I'm operating on 40 meter CW with the KX3/KAT500/KPA500. I finish my QSO and shut down the station. Sequence of power-off's doesn't seem to make any difference, but I usually turn off KX3, KPA500, KAT500. The next morning I turn on the KPA500, it is sitting at 5.3 mHz. Why?? I've never, ever used it on 60 meters. Why would it decide to default to that band? Why would it not default to the last band it was operating on? I just tried the same scenario with the K3/KPA500/KAT500 and this does not happen. When I power the KPA500 back to life, it remembers what band I was on.

Now, the interesting thing about this is that it only seems to happen after the amp has been turned off for several hours. I just now ran through this scenario and the amp remembered that I had been on 40 meters. So, what I'm seeing is only after 5 - 8 hours of power off.

Any suggestions? It isn't a big deal - just kind of strange that this amp seems to like the 60 meter band more than I do!

Jim / W6JHB
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[Jim Bennett]

So, as Lyle (KK7P) and Brian (K3KO) are saying, this is due to (1) having the KPA500 set to K3 (I do), and after the amp sits and capacitors discharge, there is no voltage coming through the acc connector and the amp goes to 60 meters.

Well, if that's the case then I guess there isn't much that can be done about it. Sighhhhh.......

Tnx, Jim
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[Jack Brindle-2]

The solution is to disconnect the AUX cable from the KPA when using the KX3.
This is not a KPA issue - you can leave the KPA500 turned on and power off the K3 and you will see the KPA switch to 60 meters after a short while.When the K3 powers off, the Vcc naturally sags to 0V. The Band line outputs are pulled up to Vcc. When the K3 internal supply goes to zero, they still pull to Vcc, which is zero. That represents 60 meters. If the KPA is on at this time, it will follow orders and go to 60 meters…

The more dangerous situation is that the K3 _may_ pull the KEY line output to zero, which keys the KPA. The real solution is to switch the K3 out of the AUX circuit when using the KPA with some other transceiver.

Jack Brindle, W6FB

On Feb 25, 2014, at 9:44 AM, Jim Bennett <[hidden email]> wrote:

> So, as Lyle (KK7P) and Brian (K3KO) are saying, this is due to (1) having the KPA500 set to K3 (I do), and after the amp sits and capacitors discharge, there is no voltage coming through the acc connector and the amp goes to 60 meters.
>
> Well, if that's the case then I guess there isn't much that can be done about it. Sighhhhh.......
>
> Tnx, Jim
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
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>
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[Nr4c]

What's the big deal?  Once the K3 is on, it should jump to whatever band the K3 is set to??

The KX3 won't tell the KPA500 what band till it spits out some ref.

...bill nr4c

Sent from my Verizon Wireless 4G LTE DROID

Jim Bennett <[hidden email]> wrote:

>So, as Lyle (KK7P) and Brian (K3KO) are saying, this is due to (1) having the KPA500 set to K3 (I do), and after the amp sits and capacitors discharge, there is no voltage coming through the acc connector and the amp goes to 60 meters.
>
>Well, if that's the case then I guess there isn't much that can be done about it. Sighhhhh.......
>
>Tnx, Jim
>______________________________________________________________
>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
>

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