K3 with xmit and receive antennas - advice needed

[John - N0EVH]

All,

My K3 does not have the option that provides for the third antenna input (KXV3).  Would the following method allow me use dual antennas for Field Day.  Use the switched 12 volt out to drive an antenna relay to make the changeover.

Will this work?  Is there a better approach?

Thanks, John N0EVH
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[Ken Kopp-3]

John,

The "switched 12V out" you're referring to is switched
on with the K3's POWER and remains in an ON state
as long as the radio is on.

There is a "keyed to ground" connection (KEY OUT)
that -might- meet your needs to switch an external
relay, but I don't know it's current / voltage limitations.

Doesn't ANT 1 and ANT 2 meet your needs?  They are
selectable with the ANT button on the front panel.

Maybe I've not understood your question .....

73! Ken Kopp- K0PP
     [hidden email]


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[Dick Dievendorff]

John:

You don't have a lot of time before this Field Day, but in the longer term,
there's a better way.

For this Field Day, I'd look for a manual switch from MFJ or Alpha-Delta or
something along those lines.

The K3 (and most other radios of recent vintage) provide back-panel "band
change" or "band level" lines that can be used for this purpose.  The K3
uses a 4-line (plus ground) BCD encoding on the back-panel accessory
connector to indicate the band. Yaesu uses the same scheme.  Band decoders
for this 4-line BCD encoding that are advertised for Yaesu products work
well with the K3.

ICOM uses a different scheme, but the idea is the same.

Available band decoders for the K3 / Yaesu 4-wire BCD protocol include:

Elecraft KRC2 http://www.elecraft.com/KRC2/krc2.htm,

Unified Microsystems BCD-10  http://www.unifiedmicro.com/decoder.html  See
the link at the bottom for a more complete description of a simple switching
system. http://www.unifiedmicro.com/BBCD10_BLK.pdf

Top Ten Devices http://www.qth.com/topten/bdecoder.htm 

Array Solutions
http://www.arraysolutions.com/Products/bandmaster.htm#top%20of%20page

and microHAM http://www.microham-usa.com/Products/band%20decoder.html

The capabilities (and prices) of these devices varies considerably.  Some of
them have many more functions than just band decoding.

These all help to automate the antenna selection process. You change the
frequency from the radio front panel (or your logging program on your
computer), the radio provides signals to the band decoder, the band decoder
provides +12V to an appropriate set of relays, and the relays select the
appropriate antenna.  Some antenna relay boxes can switch two radios to N
antennas, and isolation becomes a very important issue.  

There are antenna relay boxes available from some of the same sources. I've
seen any number of construction articles in QST and NCJ about this.  It's a
popular station automation topic for contesting stations.  In a contest,
particularly with guest operators, it's ideal if you can just change the
radio's frequency and start transmitting, everything else is automated. Some
of my current antennas require an ATU, and I have to tune my amplifier, but
I'm hoping someday to automate all that, too.  The really competitive
stations have all this automated.

You could ask this question on the TowerTalk or CQ-Contes reflector and get
lots of advice...

73 de Dick, K6KR


-----Original Message-----
From: [hidden email]
[mailto:[hidden email]] On Behalf Of John Watkins
Sent: Wednesday, June 09, 2010 3:33 PM
To: Elecraft Reflector
Subject: [Elecraft] K3 with xmit and receive antennas - advice needed

All,

My K3 does not have the option that provides for the third antenna input
(KXV3).  Would the following method allow me use dual antennas for Field
Day.  Use the switched 12 volt out to drive an antenna relay to make the
changeover.

Will this work?  Is there a better approach?

Thanks, John N0EVH
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[Jim Rhodes]

Take a look at MFJ-1707, or HB your own. I built one years ago, but
never got around to building the receive antennas, so didn't really try
it out.

Jim K0XU


On 6/9/2010 6:31 PM, Dick Dievendorff wrote:

> John:
>
> You don't have a lot of time before this Field Day, but in the longer term,
> there's a better way.
>
> For this Field Day, I'd look for a manual switch from MFJ or Alpha-Delta or
> something along those lines.
>
> The K3 (and most other radios of recent vintage) provide back-panel "band
> change" or "band level" lines that can be used for this purpose.  The K3
> uses a 4-line (plus ground) BCD encoding on the back-panel accessory
> connector to indicate the band. Yaesu uses the same scheme.  Band decoders
> for this 4-line BCD encoding that are advertised for Yaesu products work
> well with the K3.
>
> ICOM uses a different scheme, but the idea is the same.
>
> Available band decoders for the K3 / Yaesu 4-wire BCD protocol include:
>
> Elecraft KRC2 http://www.elecraft.com/KRC2/krc2.htm,
>
> Unified Microsystems BCD-10  http://www.unifiedmicro.com/decoder.html  See
> the link at the bottom for a more complete description of a simple switching
> system. http://www.unifiedmicro.com/BBCD10_BLK.pdf
>
> Top Ten Devices http://www.qth.com/topten/bdecoder.htm
>
> Array Solutions
> http://www.arraysolutions.com/Products/bandmaster.htm#top%20of%20page
>
> and microHAM http://www.microham-usa.com/Products/band%20decoder.html
>
> The capabilities (and prices) of these devices varies considerably.  Some of
> them have many more functions than just band decoding.
>
> These all help to automate the antenna selection process. You change the
> frequency from the radio front panel (or your logging program on your
> computer), the radio provides signals to the band decoder, the band decoder
> provides +12V to an appropriate set of relays, and the relays select the
> appropriate antenna.  Some antenna relay boxes can switch two radios to N
> antennas, and isolation becomes a very important issue.
>
> There are antenna relay boxes available from some of the same sources. I've
> seen any number of construction articles in QST and NCJ about this.  It's a
> popular station automation topic for contesting stations.  In a contest,
> particularly with guest operators, it's ideal if you can just change the
> radio's frequency and start transmitting, everything else is automated. Some
> of my current antennas require an ATU, and I have to tune my amplifier, but
> I'm hoping someday to automate all that, too.  The really competitive
> stations have all this automated.
>
> You could ask this question on the TowerTalk or CQ-Contes reflector and get
> lots of advice...
>
> 73 de Dick, K6KR
>
>
> -----Original Message-----
> From: [hidden email]
> [mailto:[hidden email]] On Behalf Of John Watkins
> Sent: Wednesday, June 09, 2010 3:33 PM
> To: Elecraft Reflector
> Subject: [Elecraft] K3 with xmit and receive antennas - advice needed
>
> All,
>
> My K3 does not have the option that provides for the third antenna input
> (KXV3).  Would the following method allow me use dual antennas for Field
> Day.  Use the switched 12 volt out to drive an antenna relay to make the
> changeover.
>
> Will this work?  Is there a better approach?
>
> Thanks, John N0EVH
> ______________________________________________________________
> 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
>
> ______________________________________________________________
> 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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