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K3 Ant 1 and Ant 2 Isolation?

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Rich-4

K3 Ant 1 and Ant 2 Isolation?

During FD we were discussing portable antenna options for next year.
We were considering a 33' fiberglass pole with a veritical and a G5RV on
the same pole. A 31' piece on wire running vertically down the pole and
also a G5RV supported by that same pole. Then just connect them to the
K3 Ant 1 and 2 jacks and away we go, however should we expect to flood
the Ant jack which is not in use with RF due to the antennas being so
close?

Any thoughts?

Rich
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Don Wilhelm-4

Re: K3 Ant 1 and Ant 2 Isolation?

Rich,

It all depends on how you have configured the AUX ANT input for the subRX.
If you have configured the Sub AUX ANT to use the non-transmit ANT1/2
jacks, then you may have a problem with overload and COR activation on
the non-transmit antenna. In that case, the use of some external
protection device may be prudent.

If you do not have the subRX, it should be no problem or if you have
that subRX AUX ANT connected to the BNC jack, there should not be a
problem as long as the BNC jack is left open or grounded.

The selection between ANT1 and ANT2 uses a relay, so except for the
situation posed in paragraph 1, there should not be a problem.

73,
Don W3FPR

On 7/9/2014 9:32 AM, Rich wrote:
> During FD we were discussing portable antenna options for next year.
> We were considering a 33' fiberglass pole with a veritical and a G5RV
> on the same pole. A 31' piece on wire running vertically down the
> pole and also a G5RV supported by that same pole. Then just connect
> them to the K3 Ant 1 and 2 jacks and away we go, however should we
> expect to flood the Ant jack which is not in use with RF due to the
> antennas being so close?
>

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Dave-7

Re: K3 Ant 1 and Ant 2 Isolation?

In reply to this post by Rich-4

Probably not a good idea.

The interaction between the vertical and the feed to the G5RV will be
severe. You will have large quantities of RF forced onto the G5RV feeder.

I ran a quick EZNEC model of 2 verticals 2.4" apart. It indicates that
at 100w you would induce 45w onto the feeder. Even QRP levels would
not appear to be safe. I'd think you are pretty assured of blowing
something up.

It would be an interesting experiment though, if you wanted to try it
and report back on what burned up . . .

73 de dave
ab9ca/4

On 7/9/14 8:32 AM, Rich wrote:

> During FD we were discussing portable antenna options for next year.
> We were considering a 33' fiberglass pole with a veritical and a G5RV
> on the same pole. A 31' piece on wire running vertically down the
> pole and also a G5RV supported by that same pole. Then just connect
> them to the K3 Ant 1 and 2 jacks and away we go, however should we
> expect to flood the Ant jack which is not in use with RF due to the
> antennas being so close?
>
> Any thoughts?
>
> Rich
> ______________________________________________________________
> 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]
>

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Guy Olinger K2AV

Re: K3 Ant 1 and Ant 2 Isolation?

Most interactions between feeders and antennas and other antennas and other
antennas' feeders can be managed with physical layout design and effective
attention to common mode current blocking.

To be aware of these interactions, one must cultivate vision of these
circumstances as a soup of *all* conductors. Just presume every conductor
induces every other conductor, far and away a more accurate assumption than
just considering antenna wires and assuming feedlines are invisible.

Once comfortable with that inconvenient truth about ham sites, one sees
that some combinations of wire and ferrite just aren't worth the trouble.
Too much to figure out, too much to "clean up," particularly for field day
with its time constraints.

Issues between wires are modulated by the wire/rope/support opportunities
at a given site. In my case this last FD, optimally located trees in a far
corner of the property where an RV could be parked, allowed an interesting
specially designed sloped antenna I would never have tried in more crowded
circumstances for considerable cause (long story). This particular long
sloper turned out to be a killer on 40m CW (1119 Q's at 100w). It was
removed from interaction only by the 75 yards back to the nearest station
in our 3A entry.

With the all-conductors-in-play principle firmly in mind for a carefully
planned layout of antennas and conductors, no station ever heard the other.
With a trio of K3's in operation, even with frequent SSB and CW on the same
band, we heard no crud, no crosstalk, no intermod, no transmitted phase
noise, which is a much harder to satisfy requirement than not burning out
front ends. Some considerable portion of the credit for this result goes to
the K3's front-end immunity and clean transmitted signal. BOTH the K3
immunity/clean TX signal AND the interaction-scrubbed antenna layout design
were required to achieve this result.

The question as to whether paying attention to such niceties is a handicap
to a high score will be answered firmly enough by looking for N4C in the 3A
listing in November's FD score reporting -- PVRC NC at Grey Goose Farm. And
yes, the owner did name the farm after the vodka. You should see his man
cave :>)

Making interaction go away with a simple one-size-fits-all rule just does
not happen in less than very large spaces. But understanding the
electronic physics of interactions and seeing all the conductors in the
solution, one can dance with the physics and the physical layout
possibilities to create some imaginative and excellent site-specific
solutions in the field.

EZNEC and an *all-conductor* model preliminary design is a very good start.

73, Guy K2AV

On Wed, Jul 9, 2014 at 10:15 AM, dave <[hidden email]> wrote:

>
> Probably not a good idea.
>
> The interaction between the vertical and the feed to the G5RV will be
> severe. You will have large quantities of RF forced onto the G5RV feeder.
>
> I ran a quick EZNEC model of 2 verticals 2.4" apart. It indicates that at
> 100w you would induce 45w onto the feeder. Even QRP levels would not appear
> to be safe. I'd think you are pretty assured of blowing something up.
>
> It would be an interesting experiment though, if you wanted to try it and
> report back on what burned up . . .
>
> 73 de dave
> ab9ca/4
>
>
>
>
> On 7/9/14 8:32 AM, Rich wrote:
>
>> During FD we were discussing portable antenna options for next year.
>> We were considering a 33' fiberglass pole with a veritical and a G5RV
>> on the same pole. A 31' piece on wire running vertically down the
>> pole and also a G5RV supported by that same pole. Then just connect
>> them to the K3 Ant 1 and 2 jacks and away we go, however should we
>> expect to flood the Ant jack which is not in use with RF due to the
>> antennas being so close?
>>
>> Any thoughts?
>>
>> Rich
>> ______________________________________________________________
>> 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
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>
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>

Kenneth Christiansen

Re: K3 Ant 1 and Ant 2 Isolation?

In reply to this post by Rich-4

Hi to Rich and the group

During field day I ran my KX3 with the tuner from the KXPA100 at 5 watts. I had my 44 ft doublet fed with 22 ft of window line on my 24 ft painters pole in the center with a 10 ft PVC support on each end of the doublet. I had a 33 ft MFJ fiberglass mast with 29 ft of wire fastened to it as a vertical about 2 ft away from the support for the doublet. The doublet through a W2DU balun was on antenna 1 and the vertical fed against the frame of my fiberglass camper was on antenna 2. Both antennas were pre tuned by the tuner on each band before field day started. I could chose either antenna instantly. Most of the field day the doublet was about the same as the vertical and I used it. I found the vertical to be the better antenna in the late evening and night on 40 meters so I used that. There was one weak point to my station and that was me as an operator but the KX3 and the 2 antennas worked great. I made 118 CW 5 watt battery search and pounce contacts and could have made many m
ore if I was just a better operator. I hope my experience can be of some help. I have pictures on qrz.com not of field day but of the different parts of my station I put together for field day.

73

Ken W0CZ w0cz at i29 dot net

Sent from my iPad

> On Jul 9, 2014, at 8:32 AM, Rich <[hidden email]> wrote:
>
> During FD we were discussing portable antenna options for next year. We were considering a 33' fiberglass pole with a veritical and a G5RV on the same pole. A 31' piece on wire running vertically down the pole and also a G5RV supported by that same pole. Then just connect them to the K3 Ant 1 and 2 jacks and away we go, however should we expect to flood the Ant jack which is not in use with RF due to the antennas being so close?
>
> Any thoughts?
>
> Rich
> ______________________________________________________________
> 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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