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KX2 / KPA500

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KX2 / KPA500

I’ve run into an interesting situation that has me puzzled. Probably some dumb pilot error, but after an hour or so looking through the manuals and thinking about it - I gotta call in the experts.

I’ve had a K3 for ten years and the KPA500/KAT500 for maybe four or five years. They work great. I also have a KX2 and thought “why not hook it to the KPA500 and give it some punch when I need it?”. Since my antenna connects through a coax switch between the K3 and the KX2, the output of the KX2 has been flowing through the KPA500/KAT500 since day one, although never being amplified. I set the KX2 ATU to bypass and do a “tune” on the KAT500 - finds a nice 1:1 match. Keying the KX2 with the amp in standby gives me 10w out on the KX2.

Now, with a station tuned in that is say, S8 on the KX2, when I put the amp into operate mode, the received signal strength drops about six S-units. Going back to standby on the amp restores full receive strength. I have pressed the proper band switch on the amp. When I have the amp in operate mode and transmit, I get about 190 watts out, with an SWR of 1:1.

By the way - the K3 IS connected to the amp as it normally is, but powered off.

So, it seems like the amp is not sensing the RF frequency coming out of the KX2 - but why?

Jim / W6JHB

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Michael Walker

Re: KX2 / KPA500

James

What happens if you unplug the PTT lead from the KPA500? Does your receive
return?

Mike va3mw

On Tue, Apr 28, 2020 at 3:02 PM James Bennett via Elecraft <
[hidden email]> wrote:

> I’ve run into an interesting situation that has me puzzled. Probably some
> dumb pilot error, but after an hour or so looking through the manuals and
> thinking about it - I gotta call in the experts.
>
> I’ve had a K3 for ten years and the KPA500/KAT500 for maybe four or five
> years. They work great. I also have a KX2 and thought “why not hook it to
> the KPA500 and give it some punch when I need it?”. Since my antenna
> connects through a coax switch between the K3 and the KX2, the output of
> the KX2 has been flowing through the KPA500/KAT500 since day one, although
> never being amplified. I set the KX2 ATU to bypass and do a “tune” on the
> KAT500 - finds a nice 1:1 match. Keying the KX2 with the amp in standby
> gives me 10w out on the KX2.
>
> Now, with a station tuned in that is say, S8 on the KX2, when I put the
> amp into operate mode, the received signal strength drops about six
> S-units. Going back to standby on the amp restores full receive strength. I
> have pressed the proper band switch on the amp. When I have the amp in
> operate mode and transmit, I get about 190 watts out, with an SWR of 1:1.
>
> By the way - the K3 IS connected to the amp as it normally is, but powered
> off.
>
> So, it seems like the amp is not sensing the RF frequency coming out of
> the KX2 - but why?
>
> Jim / W6JHB
>
>
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:[hidden email]
>
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> Please help support this email list: http://www.qsl.net/donate.html
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ANDY DURBIN

KX2 / KPA500

In reply to this post by Elecraft mailing list

"So, it seems like the amp is not sensing the RF frequency coming out of the KX2 - but why?"

If the KPA500 is sensing RF frequency it will display the appropriate band on its display. Does it?

Loss of RX signal could be caused by failure of the KPA500 T/R switch or it could always be selected to TX. Check for the keyed indicator (an asterisk on the left side of the KPA500 display). It is only displayed when keyed and in OPER mode.

73,
Andy, k3wyc
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Nr4c

Re: KX2 / KPA500

In reply to this post by Elecraft mailing list

First thing I’d try is to connect the KX2 directly to the amp and see what happens.

Then work out your switches.

Also, if you have tuned the KAT500 with the K3, it’s not necessary to retune with the KX2. Just By-Pass it’s tuner and go. Same antenna, right - same amp.

Sent from my iPhone
...nr4c. bill

> On Apr 28, 2020, at 3:03 PM, James Bennett via Elecraft <[hidden email]> wrote:
>
> I’ve run into an interesting situation that has me puzzled. Probably some dumb pilot error, but after an hour or so looking through the manuals and thinking about it - I gotta call in the experts.
>
> I’ve had a K3 for ten years and the KPA500/KAT500 for maybe four or five years. They work great. I also have a KX2 and thought “why not hook it to the KPA500 and give it some punch when I need it?”. Since my antenna connects through a coax switch between the K3 and the KX2, the output of the KX2 has been flowing through the KPA500/KAT500 since day one, although never being amplified. I set the KX2 ATU to bypass and do a “tune” on the KAT500 - finds a nice 1:1 match. Keying the KX2 with the amp in standby gives me 10w out on the KX2.
>
> Now, with a station tuned in that is say, S8 on the KX2, when I put the amp into operate mode, the received signal strength drops about six S-units. Going back to standby on the amp restores full receive strength. I have pressed the proper band switch on the amp. When I have the amp in operate mode and transmit, I get about 190 watts out, with an SWR of 1:1.
>
> By the way - the K3 IS connected to the amp as it normally is, but powered off.
>
> So, it seems like the amp is not sensing the RF frequency coming out of the KX2 - but why?
>
> Jim / W6JHB
>
>
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
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>
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Elecraft mailing list

Re: KX2 / KPA500

In reply to this post by Elecraft mailing list

Hi Mark,

In one of the books I have (or had), possibly the Fred Cady KX3 book, there was a diagram of connecting a KX3 along with a K3 to a KPA500/KAT500. The diagram had a splitter in use for the key line, as I recall. And when I had my KX3 that was exactly what I did, and it worked fine. There is no reason, as far as I know, why the two cannot be connected together, provided the key line interrupt device is present if one is using the KPAK3AUX cable.

I looked in my parts bin and found one of those interrupters just a few minutes ago. I disconnected the KPAK3AUX cable and inserted the interrupter at the back of the KPA500, then put the KPAK3AUX cable into it. Now, when I put the KPA500 into Operate mode, the RX level on the KX2 remains unchanged, so there was progress! Keying the KX2 now triggers the amp to do its thing when in Operate mode. I’ve got to go back and dig up my RCA splitter so I can reconnect the Key out line from the K3.

If Jack W6FB is monitoring this thread, perhaps he can chime in on the issue of having both radio’s key out lines tied together via a splitter. BTW - I NEVER have both powered on at the same time.

73, Jim / W6JHB

> On Apr 28, 2020, at 1:51 PM, Mark Goldberg <[hidden email]> wrote:
>
> You should not have the KX2 and K3 connected to the KPA500 PTT in at the same time. I think you need to disconnect the KPAK3AUX or put in a switch, not a splitter that keeps them connected at the same time. Your K3 is keeping the amp in TX. It should only be controlled by the KX2.
>
> 73,
>
> Mark
> W7MLG
>
>
> On Tue, Apr 28, 2020 at 1:28 PM James Bennett <[hidden email] <mailto:[hidden email]>> wrote:
> Hi Mark,
>
> Yes, I have the KX2ACBL accessory cable in line. That allows me to run the KX2 Ground and Key Out connections (ring 2) through another cable over to the KPA500 where it is plugged into the PA Key jack.
>
> I do not have a key out connection from the K3 to the KPA - I’m using the “enhanced” band switching with the KPAK3AUX cable. And while I was reading up on this stuff a few minutes ago I did an experiment. I powered up the K3 then put the amp into operate mode. The KX2 receive signal level did not drop. So, it appears that when the K3 is off, it pulls that connection in the KPAK3AUX cable to ground. I used to have a KX3 a million years ago and I sort of remember having to run the key out cable from the K3 to a RCA splitter - one connection to the amp and the other to the KX3, along with a key line inhibit “thing” between the K3 cable and the amp. Now I just have to find where it is. Won’t be a happy camper if I can’t find it…
>
> Thanks for your input - I “think" I’m on the right track.
>
> 73, Jim / W6JHB
>
>> On Apr 28, 2020, at 12:57 PM, Mark Goldberg <[hidden email] <mailto:[hidden email]>> wrote:
>>
>> Do you have the PTT In on the KPA500 connected to the ACC Out Ring2 as shown on page 9 of the KX2 manual? If you use a stereo cable, it will be shorted to ground and always have the amp in TX, which would result in what you are seeing.
>>
>> Did you disconnect the K3 key out from the KPA500? The KPA500 senses frequency to determine which band, but it still needs the PTT (key out) signal to tell it if it should be in TX or RX mode and that key out has to come from the radio transmitting. I have my KX3 connected to the KPA500 in a simlar fashion and disconnect the key out to tune with a couple watts, then connect it to operate.
>>
>> 73,
>>
>> Mark
>> W7MLG
>>
>> On Tue, Apr 28, 2020 at 12:02 PM James Bennett via Elecraft <[hidden email] <mailto:[hidden email]>> wrote:
>> I’ve run into an interesting situation that has me puzzled. Probably some dumb pilot error, but after an hour or so looking through the manuals and thinking about it - I gotta call in the experts.
>>
>> I’ve had a K3 for ten years and the KPA500/KAT500 for maybe four or five years. They work great. I also have a KX2 and thought “why not hook it to the KPA500 and give it some punch when I need it?”. Since my antenna connects through a coax switch between the K3 and the KX2, the output of the KX2 has been flowing through the KPA500/KAT500 since day one, although never being amplified. I set the KX2 ATU to bypass and do a “tune” on the KAT500 - finds a nice 1:1 match. Keying the KX2 with the amp in standby gives me 10w out on the KX2.
>>
>> Now, with a station tuned in that is say, S8 on the KX2, when I put the amp into operate mode, the received signal strength drops about six S-units. Going back to standby on the amp restores full receive strength. I have pressed the proper band switch on the amp. When I have the amp in operate mode and transmit, I get about 190 watts out, with an SWR of 1:1.
>>
>> By the way - the K3 IS connected to the amp as it normally is, but powered off.
>>
>> So, it seems like the amp is not sensing the RF frequency coming out of the KX2 - but why?
>>
>> Jim / W6JHB
>>
>>
>> ______________________________________________________________
>> Elecraft mailing list
>> Home: http://mailman.qth.net/mailman/listinfo/elecraft <http://mailman.qth.net/mailman/listinfo/elecraft>
>> Help: http://mailman.qth.net/mmfaq.htm <http://mailman.qth.net/mmfaq.htm>
>> Post: mailto:[hidden email] <mailto:[hidden email]>
>>
>> This list hosted by: http://www.qsl.net <http://www.qsl.net/>
>> Please help support this email list: http://www.qsl.net/donate.html <http://www.qsl.net/donate.html>
>> Message delivered to [hidden email] <mailto:[hidden email]>

Jim Brown-10

Re: KX2 / KPA500

On 4/28/2020 2:47 PM, James Bennett via Elecraft wrote:
> connecting a KX3 along with a K3 to a KPA500/KAT500. The diagram had a splitter in use for the key line, as I recall.

Yes. I've done that for years with K3 feeding KPA500 and tube amp (first
Ten Tec 425, now 87A and KPA1500). I use relays to switch coax ins and outs.

73, Jim K9YC

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Elecraft mailing list

Re: KX2 / KPA500

In reply to this post by Elecraft mailing list

Jim;

Disconnect the AUX IO cable from the KPA and try it again with the KX2.
Does it have band it likes to stay on? (I’m thinking 60 meters here).

73!
Jack, W6FB

> On Apr 28, 2020, at 2:47 PM, James Bennett via Elecraft <[hidden email]> wrote:
>
> Hi Mark,
>
> In one of the books I have (or had), possibly the Fred Cady KX3 book, there was a diagram of connecting a KX3 along with a K3 to a KPA500/KAT500. The diagram had a splitter in use for the key line, as I recall. And when I had my KX3 that was exactly what I did, and it worked fine. There is no reason, as far as I know, why the two cannot be connected together, provided the key line interrupt device is present if one is using the KPAK3AUX cable.
>
> I looked in my parts bin and found one of those interrupters just a few minutes ago. I disconnected the KPAK3AUX cable and inserted the interrupter at the back of the KPA500, then put the KPAK3AUX cable into it. Now, when I put the KPA500 into Operate mode, the RX level on the KX2 remains unchanged, so there was progress! Keying the KX2 now triggers the amp to do its thing when in Operate mode. I’ve got to go back and dig up my RCA splitter so I can reconnect the Key out line from the K3.
>
> If Jack W6FB is monitoring this thread, perhaps he can chime in on the issue of having both radio’s key out lines tied together via a splitter. BTW - I NEVER have both powered on at the same time.
>
> 73, Jim / W6JHB
>
>
>
>> On Apr 28, 2020, at 1:51 PM, Mark Goldberg <[hidden email]> wrote:
>>
>> You should not have the KX2 and K3 connected to the KPA500 PTT in at the same time. I think you need to disconnect the KPAK3AUX or put in a switch, not a splitter that keeps them connected at the same time. Your K3 is keeping the amp in TX. It should only be controlled by the KX2.
>>
>> 73,
>>
>> Mark
>> W7MLG
>>
>>
>> On Tue, Apr 28, 2020 at 1:28 PM James Bennett <[hidden email] <mailto:[hidden email]>> wrote:
>> Hi Mark,
>>
>> Yes, I have the KX2ACBL accessory cable in line. That allows me to run the KX2 Ground and Key Out connections (ring 2) through another cable over to the KPA500 where it is plugged into the PA Key jack.
>>
>> I do not have a key out connection from the K3 to the KPA - I’m using the “enhanced” band switching with the KPAK3AUX cable. And while I was reading up on this stuff a few minutes ago I did an experiment. I powered up the K3 then put the amp into operate mode. The KX2 receive signal level did not drop. So, it appears that when the K3 is off, it pulls that connection in the KPAK3AUX cable to ground. I used to have a KX3 a million years ago and I sort of remember having to run the key out cable from the K3 to a RCA splitter - one connection to the amp and the other to the KX3, along with a key line inhibit “thing” between the K3 cable and the amp. Now I just have to find where it is. Won’t be a happy camper if I can’t find it…
>>
>> Thanks for your input - I “think" I’m on the right track.
>>
>> 73, Jim / W6JHB
>>
>>> On Apr 28, 2020, at 12:57 PM, Mark Goldberg <[hidden email] <mailto:[hidden email]>> wrote:
>>>
>>> Do you have the PTT In on the KPA500 connected to the ACC Out Ring2 as shown on page 9 of the KX2 manual? If you use a stereo cable, it will be shorted to ground and always have the amp in TX, which would result in what you are seeing.
>>>
>>> Did you disconnect the K3 key out from the KPA500? The KPA500 senses frequency to determine which band, but it still needs the PTT (key out) signal to tell it if it should be in TX or RX mode and that key out has to come from the radio transmitting. I have my KX3 connected to the KPA500 in a simlar fashion and disconnect the key out to tune with a couple watts, then connect it to operate.
>>>
>>> 73,
>>>
>>> Mark
>>> W7MLG
>>>
>>> On Tue, Apr 28, 2020 at 12:02 PM James Bennett via Elecraft <[hidden email] <mailto:[hidden email]>> wrote:
>>> I’ve run into an interesting situation that has me puzzled. Probably some dumb pilot error, but after an hour or so looking through the manuals and thinking about it - I gotta call in the experts.
>>>
>>> I’ve had a K3 for ten years and the KPA500/KAT500 for maybe four or five years. They work great. I also have a KX2 and thought “why not hook it to the KPA500 and give it some punch when I need it?”. Since my antenna connects through a coax switch between the K3 and the KX2, the output of the KX2 has been flowing through the KPA500/KAT500 since day one, although never being amplified. I set the KX2 ATU to bypass and do a “tune” on the KAT500 - finds a nice 1:1 match. Keying the KX2 with the amp in standby gives me 10w out on the KX2.
>>>
>>> Now, with a station tuned in that is say, S8 on the KX2, when I put the amp into operate mode, the received signal strength drops about six S-units. Going back to standby on the amp restores full receive strength. I have pressed the proper band switch on the amp. When I have the amp in operate mode and transmit, I get about 190 watts out, with an SWR of 1:1.
>>>
>>> By the way - the K3 IS connected to the amp as it normally is, but powered off.
>>>
>>> So, it seems like the amp is not sensing the RF frequency coming out of the KX2 - but why?
>>>
>>> Jim / W6JHB
>>>
>>>
>>> ______________________________________________________________
>>> Elecraft mailing list
>>> Home: http://mailman.qth.net/mailman/listinfo/elecraft <http://mailman.qth.net/mailman/listinfo/elecraft>
>>> Help: http://mailman.qth.net/mmfaq.htm <http://mailman.qth.net/mmfaq.htm>
>>> Post: mailto:[hidden email] <mailto:[hidden email]>
>>>
>>> This list hosted by: http://www.qsl.net <http://www.qsl.net/>
>>> Please help support this email list: http://www.qsl.net/donate.html <http://www.qsl.net/donate.html>
>>> Message delivered to [hidden email] <mailto:[hidden email]>
>
> ______________________________________________________________
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> 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: KX2 / KPA500

In reply to this post by Elecraft mailing list

I went back and reread this . My question is this - with the interrupter in place, does the K3 still key the amplifier?

I suspect you are running into the issue of pull-ups on the K3 pulling the PTT signal up to Vcc. Of course Vcc when the K3 is off is 0 volts, which causes the KPA to key.
We see the same issue with the BAND lines, which is why the KPA500 switches to 60 meters shortly after the K3 is powered off.

So, I’m wondering what is going on also. More details and tests should resolve the questions.

73!
Jack, W6FB

> On Apr 28, 2020, at 2:47 PM, James Bennett via Elecraft <[hidden email]> wrote:
>
> Hi Mark,
>
> In one of the books I have (or had), possibly the Fred Cady KX3 book, there was a diagram of connecting a KX3 along with a K3 to a KPA500/KAT500. The diagram had a splitter in use for the key line, as I recall. And when I had my KX3 that was exactly what I did, and it worked fine. There is no reason, as far as I know, why the two cannot be connected together, provided the key line interrupt device is present if one is using the KPAK3AUX cable.
>
> I looked in my parts bin and found one of those interrupters just a few minutes ago. I disconnected the KPAK3AUX cable and inserted the interrupter at the back of the KPA500, then put the KPAK3AUX cable into it. Now, when I put the KPA500 into Operate mode, the RX level on the KX2 remains unchanged, so there was progress! Keying the KX2 now triggers the amp to do its thing when in Operate mode. I’ve got to go back and dig up my RCA splitter so I can reconnect the Key out line from the K3.
>
> If Jack W6FB is monitoring this thread, perhaps he can chime in on the issue of having both radio’s key out lines tied together via a splitter. BTW - I NEVER have both powered on at the same time.
>
> 73, Jim / W6JHB
>
>
>
>> On Apr 28, 2020, at 1:51 PM, Mark Goldberg <[hidden email] <mailto:[hidden email]>> wrote:
>>
>> You should not have the KX2 and K3 connected to the KPA500 PTT in at the same time. I think you need to disconnect the KPAK3AUX or put in a switch, not a splitter that keeps them connected at the same time. Your K3 is keeping the amp in TX. It should only be controlled by the KX2.
>>
>> 73,
>>
>> Mark
>> W7MLG
>>
>>
>> On Tue, Apr 28, 2020 at 1:28 PM James Bennett <[hidden email] <mailto:[hidden email]> <mailto:[hidden email] <mailto:[hidden email]>>> wrote:
>> Hi Mark,
>>
>> Yes, I have the KX2ACBL accessory cable in line. That allows me to run the KX2 Ground and Key Out connections (ring 2) through another cable over to the KPA500 where it is plugged into the PA Key jack.
>>
>> I do not have a key out connection from the K3 to the KPA - I’m using the “enhanced” band switching with the KPAK3AUX cable. And while I was reading up on this stuff a few minutes ago I did an experiment. I powered up the K3 then put the amp into operate mode. The KX2 receive signal level did not drop. So, it appears that when the K3 is off, it pulls that connection in the KPAK3AUX cable to ground. I used to have a KX3 a million years ago and I sort of remember having to run the key out cable from the K3 to a RCA splitter - one connection to the amp and the other to the KX3, along with a key line inhibit “thing” between the K3 cable and the amp. Now I just have to find where it is. Won’t be a happy camper if I can’t find it…
>>
>> Thanks for your input - I “think" I’m on the right track.
>>
>> 73, Jim / W6JHB
>>
>>> On Apr 28, 2020, at 12:57 PM, Mark Goldberg <[hidden email] <mailto:[hidden email]> <mailto:[hidden email] <mailto:[hidden email]>>> wrote:
>>>
>>> Do you have the PTT In on the KPA500 connected to the ACC Out Ring2 as shown on page 9 of the KX2 manual? If you use a stereo cable, it will be shorted to ground and always have the amp in TX, which would result in what you are seeing.
>>>
>>> Did you disconnect the K3 key out from the KPA500? The KPA500 senses frequency to determine which band, but it still needs the PTT (key out) signal to tell it if it should be in TX or RX mode and that key out has to come from the radio transmitting. I have my KX3 connected to the KPA500 in a simlar fashion and disconnect the key out to tune with a couple watts, then connect it to operate.
>>>
>>> 73,
>>>
>>> Mark
>>> W7MLG
>>>
>>> On Tue, Apr 28, 2020 at 12:02 PM James Bennett via Elecraft <[hidden email] <mailto:[hidden email]> <mailto:[hidden email] <mailto:[hidden email]>>> wrote:
>>> I’ve run into an interesting situation that has me puzzled. Probably some dumb pilot error, but after an hour or so looking through the manuals and thinking about it - I gotta call in the experts.
>>>
>>> I’ve had a K3 for ten years and the KPA500/KAT500 for maybe four or five years. They work great. I also have a KX2 and thought “why not hook it to the KPA500 and give it some punch when I need it?”. Since my antenna connects through a coax switch between the K3 and the KX2, the output of the KX2 has been flowing through the KPA500/KAT500 since day one, although never being amplified. I set the KX2 ATU to bypass and do a “tune” on the KAT500 - finds a nice 1:1 match. Keying the KX2 with the amp in standby gives me 10w out on the KX2.
>>>
>>> Now, with a station tuned in that is say, S8 on the KX2, when I put the amp into operate mode, the received signal strength drops about six S-units. Going back to standby on the amp restores full receive strength. I have pressed the proper band switch on the amp. When I have the amp in operate mode and transmit, I get about 190 watts out, with an SWR of 1:1.
>>>
>>> By the way - the K3 IS connected to the amp as it normally is, but powered off.
>>>
>>> So, it seems like the amp is not sensing the RF frequency coming out of the KX2 - but why?
>>>
>>> Jim / W6JHB
>>>
>>>
>>> ______________________________________________________________
>>> Elecraft mailing list
>>> Home: http://mailman.qth.net/mailman/listinfo/elecraft <http://mailman.qth.net/mailman/listinfo/elecraft> <http://mailman.qth.net/mailman/listinfo/elecraft <http://mailman.qth.net/mailman/listinfo/elecraft>>
>>> Help: http://mailman.qth.net/mmfaq.htm <http://mailman.qth.net/mmfaq.htm> <http://mailman.qth.net/mmfaq.htm <http://mailman.qth.net/mmfaq.htm>>
>>> Post: mailto:[hidden email] <mailto:[hidden email]> <mailto:[hidden email] <mailto:[hidden email]>>
>>>
>>> This list hosted by: http://www.qsl.net <http://www.qsl.net/> <http://www.qsl.net/ <http://www.qsl.net/>>
>>> Please help support this email list: http://www.qsl.net/donate.html <http://www.qsl.net/donate.html> <http://www.qsl.net/donate.html <http://www.qsl.net/donate.html>>
>>> Message delivered to [hidden email] <mailto:[hidden email]> <mailto:[hidden email] <mailto:[hidden email]>>
>
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Mark Goldberg

Re: KX2 / KPA500

My confusion is connecting the KPA500 to both the KX2 and K3 at the same
time. I use my KPA500 with two different radios, but it is only connected
to one of them at a time. In my case it is:

RF, RS232 and PTT in from my TS-590S
OR
RF, and PTT in from my KX3

I assumed that pull ups / downs when units are not powered up would mess
things up and they are not designed to be wired ored, especially when not
powered up. Since I don't have a K3, I don't know how it connects up.

73,

Mark
W7MLG

On Tue, Apr 28, 2020 at 4:48 PM Jack Brindle via Elecraft <
[hidden email]> wrote:

> I went back and reread this . My question is this - with the interrupter
> in place, does the K3 still key the amplifier?
>
> I suspect you are running into the issue of pull-ups on the K3 pulling the
> PTT signal up to Vcc. Of course Vcc when the K3 is off is 0 volts, which
> causes the KPA to key.
> We see the same issue with the BAND lines, which is why the KPA500
> switches to 60 meters shortly after the K3 is powered off.
>
> So, I’m wondering what is going on also. More details and tests should
> resolve the questions.
>
> 73!
> Jack, W6FB

Nr4c

Re: KX2 / KPA500

I’m not sure what connections are made between each radio and the amp and the other radio.

Sent from my iPhone
...nr4c. bill

> On Apr 28, 2020, at 8:35 PM, Mark Goldberg <[hidden email]> wrote:
>
> My confusion is connecting the KPA500 to both the KX2 and K3 at the same
> time. I use my KPA500 with two different radios, but it is only connected
> to one of them at a time. In my case it is:
>
> RF, RS232 and PTT in from my TS-590S
> OR
> RF, and PTT in from my KX3
>
> I assumed that pull ups / downs when units are not powered up would mess
> things up and they are not designed to be wired ored, especially when not
> powered up. Since I don't have a K3, I don't know how it connects up.
>
> 73,
>
> Mark
> W7MLG
>
>
>> On Tue, Apr 28, 2020 at 4:48 PM Jack Brindle via Elecraft <
>> [hidden email]> wrote:
>>
>> I went back and reread this . My question is this - with the interrupter
>> in place, does the K3 still key the amplifier?
>>
>> I suspect you are running into the issue of pull-ups on the K3 pulling the
>> PTT signal up to Vcc. Of course Vcc when the K3 is off is 0 volts, which
>> causes the KPA to key.
>> We see the same issue with the BAND lines, which is why the KPA500
>> switches to 60 meters shortly after the K3 is powered off.
>>
>> So, I’m wondering what is going on also. More details and tests should
>> resolve the questions.
>>
>> 73!
>> Jack, W6FB
> ______________________________________________________________
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Elecraft mailing list

Re: KX2 / KPA500 (resolved)

In reply to this post by Mark Goldberg

Let me answer a couple questions here in one message.

Jack - I recall from working with you several years ago on a similar situation that indeed, the amp “defaults” to 60 meters when the K3 is off.

Also, with the interrupter in place, and NO cable between K3 Key Out and amp, the K3 does NOT key the amp.

So, I now have it working perfectly, as I did when I had a KX3 many moons ago. Here is the setup:

——> KPAK3AUX cable and Key Line Interrupter between K3 and KPA500. Two-way RCA jack splitter plugged into the PA Key on the KPA500; one cable to the K3 Key Out, the other to the KX2 Acc port (ring 2 and shield).

With this configuration, either the K3 or the KX2 can key the KPA500 and drive it as desired.

I see that in the KPA500 manual, Rev D, 3/10/2017, the diagram indicates “Break Key Line to Insert External Equipment”. Interestingly, it also shows the line from the amp going to the K3 Key jack, which I don’t think is correct - it should point to the second jack from the right - the Key Out connection, right?

Jack - do you see any problem in doing the connections as I’ve done? seems to work fine, and I’ve not seen any smoke escaping from either rig!

Jim / W6JHB

> On Apr 28, 2020, at 5:33 PM, Mark Goldberg <[hidden email]> wrote:
>
> My confusion is connecting the KPA500 to both the KX2 and K3 at the same time. I use my KPA500 with two different radios, but it is only connected to one of them at a time. In my case it is:
>
> RF, RS232 and PTT in from my TS-590S
> OR
> RF, and PTT in from my KX3
>
> I assumed that pull ups / downs when units are not powered up would mess things up and they are not designed to be wired ored, especially when not powered up. Since I don't have a K3, I don't know how it connects up.
>
> 73,
>
> Mark
> W7MLG
>
>
> On Tue, Apr 28, 2020 at 4:48 PM Jack Brindle via Elecraft <[hidden email] <mailto:[hidden email]>> wrote:
> I went back and reread this . My question is this - with the interrupter in place, does the K3 still key the amplifier?
>
> I suspect you are running into the issue of pull-ups on the K3 pulling the PTT signal up to Vcc. Of course Vcc when the K3 is off is 0 volts, which causes the KPA to key.
> We see the same issue with the BAND lines, which is why the KPA500 switches to 60 meters shortly after the K3 is powered off.
>
> So, I’m wondering what is going on also. More details and tests should resolve the questions.
>
> 73!
> Jack, W6FB