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Occasional second radio use with KPA500

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Chuck Chandler

Occasional second radio use with KPA500

I've been using the K3S, P3, KPA500 and KAT500 as my main radio. All three
antennas are selected by the KAT500. I also have a second radio, an older
Yaesu FT-101ZD. This rig can be switched into the lineup in place of the
K3S. I sometimes enjoy using the older rig. In this manner the FT101ZD
output goes through the KPA, then the KAT. I find the KAT plays well, a
little tap of the key will cause it to auto-tune.

I'd like to be able to use the KPA500 as an amplifier, but so far it won't
key. I've tried the RCA Phono plug into the PA Key jack, but as long as
the K3S is connected the KPA won't go into TX without the proper software
signal. I did try with the software keyline interrupter a few months ago,
but that prevented the K3S from switching the amp unless I also used a
Y-connecter and phono cord from the K3S for amp keying. When I did the
keying didn't seem as crisp, though.

The K-Line is all connected as in the diagram on page 5 of the KAT500
manual.

Ideally, I could turn off the K3S, switch the feedline from the K3S to the
101ZD, and have use of both the tuner and amp. Is there an easy way to do
this? Perhaps one of those breakout boxes? Any hints appreciated!

73 de Chuck, WS1L

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NJ8M

Re: Occasional second radio use with KPA500

I think that here is your answer:

https://www.dxengineering.com/search/brand/acom/product-line/acom-2s1-automatic-two-transceiver-commutators?autoview=SKU&sortby=Default&sortorder=Ascending

Granted it is pricey but will probably work for you.

73, Morgan NJ8M

On Thu, Feb 4, 2021 at 10:48 AM Chuck Chandler <[hidden email]>
wrote:

> I've been using the K3S, P3, KPA500 and KAT500 as my main radio. All three
> antennas are selected by the KAT500. I also have a second radio, an older
> Yaesu FT-101ZD. This rig can be switched into the lineup in place of the
> K3S. I sometimes enjoy using the older rig. In this manner the FT101ZD
> output goes through the KPA, then the KAT. I find the KAT plays well, a
> little tap of the key will cause it to auto-tune.
>
> I'd like to be able to use the KPA500 as an amplifier, but so far it won't
> key. I've tried the RCA Phono plug into the PA Key jack, but as long as
> the K3S is connected the KPA won't go into TX without the proper software
> signal. I did try with the software keyline interrupter a few months ago,
> but that prevented the K3S from switching the amp unless I also used a
> Y-connecter and phono cord from the K3S for amp keying. When I did the
> keying didn't seem as crisp, though.
>
> The K-Line is all connected as in the diagram on page 5 of the KAT500
> manual.
>
> Ideally, I could turn off the K3S, switch the feedline from the K3S to the
> 101ZD, and have use of both the tuner and amp. Is there an easy way to do
> this? Perhaps one of those breakout boxes? Any hints appreciated!
>
> 73 de Chuck, WS1L
>
> [hidden email]
> ______________________________________________________________
> 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
> Message delivered to [hidden email]
>

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Lou W0FK

Re: Occasional second radio use with KPA500

NJ8M wrote
>> Ideally, I could turn off the K3S, switch the feedline from the K3S to
>> the
>> 101ZD, and have use of both the tuner and amp. Is there an easy way to
>> do
>> this? Perhaps one of those breakout boxes? Any hints appreciated!

I use a StationProII, which unfortunately is no longer in production, but
there's a decent resale market for them.

http://www.w8zr.net/stationpro/

I currently have 2 amps and 2 radios, but have had more at one time or
another. The SPII allows me to swap in any radio and amp combination I want,
and it transfers control lines so you don't have the issue you mentioned.
When I had my K3S connected to my KPA1500 via the Elecraft control
connections, I could use another radio without any issues.

73, Lou W0FK

--
Sent from: http://elecraft.365791.n2.nabble.com/
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Tim Tucker

Re: Occasional second radio use with KPA500

W2IHY has switch box solutions that should do the trick.

Tim

On Thu, Feb 4, 2021 at 11:57 AM Lou W0FK <[hidden email]> wrote:

> NJ8M wrote
> >> Ideally, I could turn off the K3S, switch the feedline from the K3S to
> >> the
> >> 101ZD, and have use of both the tuner and amp. Is there an easy way to
> >> do
> >> this? Perhaps one of those breakout boxes? Any hints appreciated!
>
> I use a StationProII, which unfortunately is no longer in production, but
> there's a decent resale market for them.
>
> http://www.w8zr.net/stationpro/
>
> I currently have 2 amps and 2 radios, but have had more at one time or
> another. The SPII allows me to swap in any radio and amp combination I
> want,
> and it transfers control lines so you don't have the issue you mentioned.
> When I had my K3S connected to my KPA1500 via the Elecraft control
> connections, I could use another radio without any issues.
>
> 73, Lou W0FK
>
>
>
>
> --
> Sent from: http://elecraft.365791.n2.nabble.com/
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
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>
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> Please help support this email list: http://www.qsl.net/donate.html
> Message delivered to [hidden email]
>

--
Owner, worldwidedx.com
AE6LX, Amateur Radio
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Frank Scolaro

Re: Occasional second radio use with KPA500

In reply to this post by NJ8M

It's a bit pricey, but I use the 1A2R switch from 4O3A:

https://4o3a.com/1-amp-2-radios-switch

Works great, switches my KPA between two rigs...

Frank, W2YK

On 2/4/2021 1:10 PM, Morgan Bailey wrote:

> I think that here is your answer:
>
> https://www.dxengineering.com/search/brand/acom/product-line/acom-2s1-automatic-two-transceiver-commutators?autoview=SKU&sortby=Default&sortorder=Ascending
>
> Granted it is pricey but will probably work for you.
>
> 73, Morgan NJ8M
>
> On Thu, Feb 4, 2021 at 10:48 AM Chuck Chandler <[hidden email]>
> wrote:
>
>> I've been using the K3S, P3, KPA500 and KAT500 as my main radio. All three
>> antennas are selected by the KAT500. I also have a second radio, an older
>> Yaesu FT-101ZD. This rig can be switched into the lineup in place of the
>> K3S. I sometimes enjoy using the older rig. In this manner the FT101ZD
>> output goes through the KPA, then the KAT. I find the KAT plays well, a
>> little tap of the key will cause it to auto-tune.
>>
>> I'd like to be able to use the KPA500 as an amplifier, but so far it won't
>> key. I've tried the RCA Phono plug into the PA Key jack, but as long as
>> the K3S is connected the KPA won't go into TX without the proper software
>> signal. I did try with the software keyline interrupter a few months ago,
>> but that prevented the K3S from switching the amp unless I also used a
>> Y-connecter and phono cord from the K3S for amp keying. When I did the
>> keying didn't seem as crisp, though.
>>
>> The K-Line is all connected as in the diagram on page 5 of the KAT500
>> manual.
>>
>> Ideally, I could turn off the K3S, switch the feedline from the K3S to the
>> 101ZD, and have use of both the tuner and amp. Is there an easy way to do
>> this? Perhaps one of those breakout boxes? Any hints appreciated!
>>
>> 73 de Chuck, WS1L
>>
>> [hidden email]
>> ______________________________________________________________
>> 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 to [hidden email]
>>
> ______________________________________________________________
> 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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> Message delivered to [hidden email]
>

Elecraft mailing list

Re: Occasional second radio use with KPA500

This is where Fred Cady’s book “The Elecraft KPA500 Amplifier and KAT500 Tuner” really helps out. It has an excellent discussion about using the KPA500 with two radios (but not at the same time…).
The RF paths need to be switched with a good RF switch, making sure that very little signal from the transmitter gets through to the *other* transceiver’s receiver. Depending on the radios, it is possible for an Elecraft radio to use the PTT line in the AUX I/O connection, and the other radio to use the RCA jack PTT. You have to be very careful with this, however. Modern radios output a 0 - 5 volt signal on their Key output, grounding the output for transmit. This is exactly what the KPA500 is looking for, although the non-transmit level can simply float (all Open-Collector). It is the ground to transmit that is important.
Older radios may have a signal that far exceeds these levels, for example the old tube-type radios using grid-block keying may put a large negative voltage on the PTT output. This will not do well in the KPA500 circuitry. In this case the radio should drive a relay that keys the amplifier.

So, yes it is quite possible to have the KPA500 driven from more than one radio through a selector switch. You just have to do it right. A copy of Fred’s book can show you the way.

73!
Jack, W6FB
And yes, I still really miss Fred...

> On Feb 4, 2021, at 3:34 PM, Frank Scolaro <[hidden email]> wrote:
>
> It's a bit pricey, but I use the 1A2R switch from 4O3A:
>
> https://4o3a.com/1-amp-2-radios-switch <https://4o3a.com/1-amp-2-radios-switch>
>
> Works great, switches my KPA between two rigs...
>
> Frank, W2YK
>
> On 2/4/2021 1:10 PM, Morgan Bailey wrote:
>> I think that here is your answer:
>> https://www.dxengineering.com/search/brand/acom/product-line/acom-2s1-automatic-two-transceiver-commutators?autoview=SKU&sortby=Default&sortorder=Ascending
>> Granted it is pricey but will probably work for you.
>> 73, Morgan NJ8M
>> On Thu, Feb 4, 2021 at 10:48 AM Chuck Chandler <[hidden email]>
>> wrote:
>>> I've been using the K3S, P3, KPA500 and KAT500 as my main radio. All three
>>> antennas are selected by the KAT500. I also have a second radio, an older
>>> Yaesu FT-101ZD. This rig can be switched into the lineup in place of the
>>> K3S. I sometimes enjoy using the older rig. In this manner the FT101ZD
>>> output goes through the KPA, then the KAT. I find the KAT plays well, a
>>> little tap of the key will cause it to auto-tune.
>>>
>>> I'd like to be able to use the KPA500 as an amplifier, but so far it won't
>>> key. I've tried the RCA Phono plug into the PA Key jack, but as long as
>>> the K3S is connected the KPA won't go into TX without the proper software
>>> signal. I did try with the software keyline interrupter a few months ago,
>>> but that prevented the K3S from switching the amp unless I also used a
>>> Y-connecter and phono cord from the K3S for amp keying. When I did the
>>> keying didn't seem as crisp, though.
>>>
>>> The K-Line is all connected as in the diagram on page 5 of the KAT500
>>> manual.
>>>
>>> Ideally, I could turn off the K3S, switch the feedline from the K3S to the
>>> 101ZD, and have use of both the tuner and amp. Is there an easy way to do
>>> this? Perhaps one of those breakout boxes? Any hints appreciated!
>>>
>>> 73 de Chuck, WS1L
>>>
>>> [hidden email]
>>> ______________________________________________________________
>>> 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 to [hidden email]
>>>
>> ______________________________________________________________
>> 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 to [hidden email] <mailto:[hidden email]>
>
> ______________________________________________________________
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>
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john@kk9a.com

Re: Occasional second radio use with KPA500

In reply to this post by Chuck Chandler

I believe the Acom 2S1 was designed for Yaesu FT1000MP transceivers. To use
one with an Elecraft you need another device to convert the inhibit voltage.

John KK9A

Morgan Bailey NJ8M wrote:

I think that here is your answer:

https://www.dxengineering.com/search/brand/acom/product-line/acom-2s1-automa
tic-two-transceiver-commutators?autoview=SKU&sortby=Default&sortorder=Ascend
ing

Granted it is pricey but will probably work for you.

73, Morgan NJ8M

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