Elecraft

Using external SDR and a K3 as antenna splitter

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NK7Z

Using external SDR and a K3 as antenna splitter

A few years ago someone posted a method of using a splitter, and the
External Antenna jacks to feed an external SDR with the direct antenna,
not a IF, but a wideband signal from the primary antenna...

I think it was something along the lines of add a splitter, between the
RX Antenna in/out, and then picking off the antenna feed to the SDR from
an output of the splitter... Does this make sense?

Is there a high level block diagram showing the antenna pathing for a
K3, with the ATU installed, and how the front panel switch labeled RX
ANT controls the signal path?

--
73, and thanks,
Dave (NK7Z)
https://www.nk7z.net
ARRL Volunteer Examiner
ARRL Technical Specialist
ARRL Asst. Director, NW Division, Technical Resources
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Rick Tavan-2

Re: Using external SDR and a K3 as antenna splitter

You can use a splitter or a simple T-connector. Connect RX ANT OUT to the
center port and RX ANT IN and the SDR to the "side" ports. Of course, with
a T-connector, all 3 ports are equivalent. Then turn on RX ANT from the
front panel. You lose 3 dB but that shouldn't be much of an issue on HF.

Yes, IIRC the Operator's Manual for K3 includes a good antenna routing
diagram.

/Rick N6XI

On Mon, Nov 18, 2019 at 8:08 AM Dave Cole <[hidden email]> wrote:

> A few years ago someone posted a method of using a splitter, and the
> External Antenna jacks to feed an external SDR with the direct antenna,
> not a IF, but a wideband signal from the primary antenna...
>
> I think it was something along the lines of add a splitter, between the
> RX Antenna in/out, and then picking off the antenna feed to the SDR from
> an output of the splitter... Does this make sense?
>
> Is there a high level block diagram showing the antenna pathing for a
> K3, with the ATU installed, and how the front panel switch labeled RX
> ANT controls the signal path?
>
> --
> 73, and thanks,
> Dave (NK7Z)
> https://www.nk7z.net
> ARRL Volunteer Examiner
> ARRL Technical Specialist
> ARRL Asst. Director, NW Division, Technical Resources
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
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>
> 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]
>

--
--

Rick Tavan
Truckee and Saratoga, CA
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Martin Sole-3

Re: Using external SDR and a K3 as antenna splitter

In reply to this post by NK7Z

I think that's pretty much it Dave. Take a cable from the Rx ant out,
feed it to one port of a 3 way tee, take the second port to Rx Ant in.
Take third port of the tee to the SDR. There will be loss of course in
both paths depending on the impedance of the SDR. If your fussy you can
invest in a mini circuits splitter and use it to replace the tee. There
will still be loss but the impedances will be better matched and
defined, if that's important. To make it work you need to use the Rx Ant
switch on the K3 to send signal out the Rx ant out jack and receive on
the Rx ant in so feeding the SDR as well otherwise the jacks are
bypassed and only the K3 works, as normal.

Martin, HS0ZED

On 18/11/2019 23:06, Dave Cole wrote:

> A few years ago someone posted a method of using a splitter, and the
> External Antenna jacks to feed an external SDR with the direct
> antenna, not a IF, but a wideband signal from the primary antenna...
>
> I think it was something along the lines of add a splitter, between
> the RX Antenna in/out, and then picking off the antenna feed to the
> SDR from an output of the splitter... Does this make sense?
>
> Is there a high level block diagram showing the antenna pathing for a
> K3, with the ATU installed, and how the front panel switch labeled RX
> ANT controls the signal path?
>

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Don Wilhelm

Re: Using external SDR and a K3 as antenna splitter

In reply to this post by NK7Z

Dave,

There in a block diagram in the back of the K3 manual.
The RX ANT OUT is what you are looking for - but remember that it has
the Low Pass Filter in the path, so the response at frequencies higher
than the band the K3 is tuned to will be attenuated.

If you need a direct antenna connection, you will have to use a splitter
on the antenna and some means of protecting the SDR during K3 transmit.
Alternately, use a separate RX antenna on the SDR (you may still need
protection for the SDR unless the TX antenna is located far enough from
the RX antenna.

73,
Don W3FPR

On 11/18/2019 11:06 AM, Dave Cole wrote:

NK7Z

Re: Using external SDR and a K3 as antenna splitter

Many thanks to all who answered!!

I was wondering if there was any sort of filtering on that jack pair...
Sorry to see that...

I have a minicircuits three way, and will be adding that, alas, the
filtering will be something to work around... THANKS for the info Don!!!!

73, and thanks,
Dave (NK7Z)
https://www.nk7z.net
ARRL Volunteer Examiner
ARRL Technical Specialist
ARRL Asst. Director, NW Division, Technical Resources

On 11/18/19 8:26 AM, Don Wilhelm wrote:

> Dave,
>
> There in a block diagram in the back of the K3 manual.
> The RX ANT OUT is what you are looking for - but remember that it has
> the Low Pass Filter in the path, so the response at frequencies higher
> than the band the K3 is tuned to will be attenuated.
>
> If you need a direct antenna connection, you will have to use a splitter
> on the antenna and some means of protecting the SDR during K3 transmit.
> Alternately, use a separate RX antenna on the SDR (you may still need
> protection for the SDR unless the TX antenna is located far enough from
> the RX antenna.
>
> 73,
> Don W3FPR
>
> On 11/18/2019 11:06 AM, Dave Cole wrote:
>> A few years ago someone posted a method of using a splitter, and the
>> External Antenna jacks to feed an external SDR with the direct
>> antenna, not a IF, but a wideband signal from the primary antenna...
>>
>> I think it was something along the lines of add a splitter, between
>> the RX Antenna in/out, and then picking off the antenna feed to the
>> SDR from an output of the splitter... Does this make sense?
>>
>> Is there a high level block diagram showing the antenna pathing for a
>> K3, with the ATU installed, and how the front panel switch labeled RX
>> ANT controls the signal path?
>>

dd0vs

Re: Using external SDR and a K3 as antenna splitter

In reply to this post by NK7Z

Hello,
I am using a splitter in the external RX path as shown on my QRZ page.

So the Splitter and the SDR are protected from high Power load.

Hope that helps
Vy73
Harald
DD0VS

Von meinem iPhone gesendet

> Am 18.11.2019 um 17:10 schrieb Dave Cole <[hidden email]>:
>
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N4ZR

Re: Using external SDR and a K3 as antenna splitter

In reply to this post by NK7Z

I was just asking myself the same question. There is probably a drawing
in the Cady book, but the best explanation in the manual is in words,
not pictures, on page 39. In any case, you are exactly correct in your
description of the RX Out-Splitter-RX In loop. The only downside is a
loss of 3-4 dB due to the splitter, and the fact that you're taking up
the RX In jack which you might otherwise use for a receiving antenna.
You must select the RX antenna to connect the IN/OUT loop to the main
antenna

73, Pete N4ZR
Check out the Reverse Beacon Network
at <http://reversebeacon.net>, now
spotting RTTY activity worldwide.
For spots, please use your favorite
"retail" DX cluster.

On 11/18/2019 11:06 AM, Dave Cole wrote:

Björn Ekelund

Re: Using external SDR and a K3 as antenna splitter

Bob N6TV made a very nice presentation a few years ago, which included a
description.

He has published it here http://tinyurl.com/4zama4

73,

Björn SM7IUN

Den mån 18 nov. 2019 kl 23:04 skrev N4ZR <[hidden email]>:

> I was just asking myself the same question. There is probably a drawing
> in the Cady book, but the best explanation in the manual is in words,
> not pictures, on page 39. In any case, you are exactly correct in your
> description of the RX Out-Splitter-RX In loop. The only downside is a
> loss of 3-4 dB due to the splitter, and the fact that you're taking up
> the RX In jack which you might otherwise use for a receiving antenna.
> You must select the RX antenna to connect the IN/OUT loop to the main
> antenna
>
> 73, Pete N4ZR
> Check out the Reverse Beacon Network
> at <http://reversebeacon.net>, now
> spotting RTTY activity worldwide.
> For spots, please use your favorite
> "retail" DX cluster.
>
> On 11/18/2019 11:06 AM, Dave Cole wrote:
> > A few years ago someone posted a method of using a splitter, and the
> > External Antenna jacks to feed an external SDR with the direct
> > antenna, not a IF, but a wideband signal from the primary antenna...
> >
> > I think it was something along the lines of add a splitter, between
> > the RX Antenna in/out, and then picking off the antenna feed to the
> > SDR from an output of the splitter... Does this make sense?
> >
> > Is there a high level block diagram showing the antenna pathing for a
> > K3, with the ATU installed, and how the front panel switch labeled RX
> > ANT controls the signal path?
> >
> ______________________________________________________________
> 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]

Dave Johnson

Re: Using external SDR and a K3 as antenna splitter

In reply to this post by NK7Z

See:
https://www.qsl.net/g4aon/elecraft_mods/

73 Dave
--
Sent from my iPhone SE
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