K3 Antenna 1/2 Operation

[Craig Smith]

This is a question and perhaps a request about the operation of the antenna
1/2 selection in conjunction with the KAT3 internal K3 antenna tuner.  

In my normal contest setup here I use two antennas on the same band.  One is
resonant so I don't need the ATU.  The other is a multi-band doublet that I
use the KAT3 to tune.  The beauty of this is that I can quickly switch from
one to the other with the K3 front panel ANT switch to select the one with
the stronger signal.  The problem is that the state of the ATU (bypass or
engaged) has to be reset each time I switch antennas.  This is an extra step
and one that can easily be forgotten in a contest situation.  Am I
overlooking something here?  That is, is there a way to set up the K3 so
that it remembers if the ATU is engaged or bypassed on a given antenna?
This would be a MUCH preferred mode of operation.  It has been awhile since
I've had my K2, but my recollection (which may be wrong) is that the K2 did
provide exactly this desired operation.  

Question:  Can I set up the K3 to do this?    

If not, Request:  Can this be provided in a future firmware update?


        Thanks and 73
                                ... Craig   AC0DS




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[n6wg]

Craig
On the antenna port where you would like
the ATU to be in BYPASS mode, instead load
that port into a 50 ohm load and run the ATU.
The other port can then match whatever antenna
you throw at it, but when you switch back to
the "bypass" port, you won't have to remember to
fuss with the ATU.
Good luck and 73
Bob N6WG

----- Original Message -----
From: "Craig D. Smith" <[hidden email]>
To: <[hidden email]>
Sent: Tuesday, May 13, 2008 6:22 AM
Subject: [Elecraft] K3 Antenna 1/2 Operation


This is a question and perhaps a request about the operation of the
antenna
1/2 selection in conjunction with the KAT3 internal K3 antenna tuner.

In my normal contest setup here I use two antennas on the same band.
One is
resonant so I don't need the ATU.  The other is a multi-band doublet
that I
use the KAT3 to tune.  The beauty of this is that I can quickly switch
from
one to the other with the K3 front panel ANT switch to select the one
with
the stronger signal.  The problem is that the state of the ATU (bypass
or
engaged) has to be reset each time I switch antennas.  This is an
extra step
and one that can easily be forgotten in a contest situation.  Am I
overlooking something here?  That is, is there a way to set up the K3
so
that it remembers if the ATU is engaged or bypassed on a given
antenna?
This would be a MUCH preferred mode of operation.  It has been awhile
since
I've had my K2, but my recollection (which may be wrong) is that the
K2 did
provide exactly this desired operation.

Question:  Can I set up the K3 to do this?

If not, Request:  Can this be provided in a future firmware update?


        Thanks and 73
                                ... Craig   AC0DS




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[Vic K2VCO]

Craig D. Smith wrote:

> In my normal contest setup here I use two antennas on the same band.  One is
> resonant so I don't need the ATU.  The other is a multi-band doublet that I
> use the KAT3 to tune.  The beauty of this is that I can quickly switch from
> one to the other with the K3 front panel ANT switch to select the one with
> the stronger signal.  The problem is that the state of the ATU (bypass or
> engaged) has to be reset each time I switch antennas.

The ATU settings are per-antenna (and of course per-band). Just tune the
ATU for each antenna and you will be fine.

Note that even when the ATU is set to BYPASS there are still some tuner
components in the circuit, to compensate for stray reactance of the
board traces, etc. BYPASS really means "matched for a 50 ohm resistive
load".
--
73,
Vic, K2VCO
Fresno CA
http://www.qsl.net/k2vco
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[KM5Q]

I have the same concern as Craig. The recommendation from Robert and Vic don't work on my K3.

Here's my scheme:
Ant. 1 is a non-resonant dipole. On 20m for example, SWR is 4.5:1. The ATU brings it to 1:1.
Ant. 2 is a screwdriver vertical on tin roof, adjusted (with ATU bypassed) to show 1:1.

I set the ATU for for either antenna, or one then the other, but it NEVER auto-adjusts when I switch antennas. Never on any band or with any (mis)tuning of my vertical, have I heard more than one relay click  when switching ANT 1/2 (no ATU reset).

I'm running the new Beta FW now (no problem) and it's my third FW version.

Windy KM5Q
K3 #764
Santa Fe, NM

[n6wg]

I think I see the problem.

An ATU does not normally "autoadjust".  You have
to tell it that you want it to run.

You first set up the ATU with ant1 at whatever frequency
you want to use.  Then switch to ant2 and again set it up.
Now both antennas are matched on that frequency.

>From now on, you just switch between antennas and they
are already matched and ready to go.  The ATU remembers
its settings for each antenna until you change them.

If you switch to another band, you redo the matching, but
when you switch back to the first band, the memory remembers
the correct match for each antenna and resets itself accordingly.
And if you jump back to the second band again, the ATU remembers
the correct settings and is ready to go on that band.

Great feature.

Good luck and 73
Bob N6WG

----- Original Message -----
From: "Windy Dankoff KM5Q" <[hidden email]>
To: <[hidden email]>
Sent: Tuesday, May 13, 2008 9:34 AM
Subject: Re: [Elecraft] K3 Antenna 1/2 Operation


>
> I have the same concern as Craig. The recommendation from Robert and
Vic
> don't work on my K3.
>
> Here's my scheme:
> Ant. 1 is a non-resonant dipole. On 20m for example, SWR is 4.5:1.
The ATU
> brings it to 1:1.
> Ant. 2 is a screwdriver vertical on tin roof, adjusted (with ATU
bypassed)
> to show 1:1.
>
> I set the ATU for for either antenna, or one then the other, but it
NEVER
> auto-adjusts when I switch antennas. Never on any band or with any
> (mis)tuning of my vertical, have I heard more than one relay click
when
> switching ANT 1/2 (no ATU reset).
>
> I'm running the new Beta FW now (no problem) and it's my third FW
version.
>
> Windy KM5Q
> K3 #764
> Santa Fe, NM
> --
> View this message in context:
http://www.nabble.com/K3-Antenna-1-2-Operation-tp17208306p17212835.html

> Sent from the Elecraft mailing list archive at Nabble.com.
>
> _______________________________________________
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>
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> Elecraft web page: http://www.elecraft.com

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[KM5Q]

Thanks Robert and Craig.

I got it! In fact, I had it all along. I had been manually resetting ATU with every band change, not knowing it was doing it for me! I can't tell the difference between hearing one relay click and numerous relays are clicking simultaneously -- they sound like one click to me, not even perceptibly louder. I didn't believe it was working until I made as variety of tests.  My previous rig is 30 years old. I'm still in Rip Van Winkle mode. All join now, as we proclaim "by golly".

Windy KM5Q
K3 #764

[Vic K2VCO]

Windy Dankoff KM5Q wrote:

> I have the same concern as Craig. The recommendation from Robert and Vic
> don't work on my K3.
>
> Here's my scheme:
> Ant. 1 is a non-resonant dipole. On 20m for example, SWR is 4.5:1. The ATU
> brings it to 1:1.
> Ant. 2 is a screwdriver vertical on tin roof, adjusted (with ATU bypassed)
> to show 1:1.
>
> I set the ATU for for either antenna, or one then the other, but it NEVER
> auto-adjusts when I switch antennas. Never on any band or with any
> (mis)tuning of my vertical, have I heard more than one relay click  when
> switching ANT 1/2 (no ATU reset).

Adjust the screwdriver coil for 1:1 on (for example) 7.2 MHz in BYPASS,
then switch the tuner on, and tap ATU TUNE.

Then if you switch to that antenna on 7.2 you should always get 1:1.

Keep in mind that a screwdriver has a narrow bandwidth on the low bands
and so you may have to retune if you QSY. This is not automatic with the K3.

So, I see two possibilities: either you didn't turn the tuner on and
retune after adjusting the screwdriver coil in BYPASS, or you are far
enough away from the original frequency that the SWR is high.

I guess it's possible that there's something wrong with your tuner, but
it's not a firmware issue.

--
73,
Vic, K2VCO
Fresno CA
http://www.qsl.net/k2vco
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[Julian, G4ILO]

I am one of the people who requested that the ATU active / bypass settings could be stored along with ANT 1 / 2. The reason was that the antenna I don't want the ATU in circuit for is externally tuned. I still need to put out a tuning signal, and I guess that having the ATU in circuit might confuse the SWR readings when I am tuning. At the back of my mind I was probably also thinking that the KAT would auto-retune in the presence of a high SWR, like the external SGC tuners do.

Even though there is a workaround of tuning the ATU into 50 ohms, I would still like to have the ATU in / out settings stored. The reason is that I have to remember which of two TUNE buttons to press depending on which antenna I am using. If I am using the externally tuned antenna and the ATU is active and I press ATU TUNE instead of TUNE by mistake, the KAT will try to match the antenna, and my previous adjustment of it into 50 ohms will be lost. If the ATU is automatically bypassed when I select the antenna that doesn't need it, nothing happens if I press the button in error. And believe me, I often press things in error.

[David Cutter]

I agree completely

David
G3UNA

>
> I am one of the people who requested that the ATU active / bypass settings
> could be stored along with ANT 1 / 2. The reason was that the antenna I
> don't want the ATU in circuit for is externally tuned. I still need to put
> out a tuning signal, and I guess that having the ATU in circuit might
> confuse the SWR readings when I am tuning. At the back of my mind I was
> probably also thinking that the KAT would auto-retune in the presence of a
> high SWR, like the external SGC tuners do.
>
> Even though there is a workaround of tuning the ATU into 50 ohms, I would
> still like to have the ATU in / out settings stored. The reason is that I
> have to remember which of two TUNE buttons to press depending on which
> antenna I am using. If I am using the externally tuned antenna and the ATU
> is active and I press ATU TUNE instead of TUNE by mistake, the KAT will
> try
> to match the antenna, and my previous adjustment of it into 50 ohms will
> be
> lost. If the ATU is automatically bypassed when I select the antenna that
> doesn't need it, nothing happens if I press the button in error. And
> believe
> me, I often press things in error.
>
> -----
> Julian, G4ILO  K3 s/n: 222 K2 s/n: 392

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[wayne burdick]

Windy Dankoff KM5Q wrote:

> I set the ATU for for either antenna, or one then the other, but it
> NEVER
> auto-adjusts when I switch antennas. Never on any band or with any
> (mis)tuning of my vertical, have I heard more than one relay click  
> when
> switching ANT 1/2 (no ATU reset).

Windy,

The relays on the KAT3 are very quiet. Multiple relays are definitely
being switched when you go from one antenna to the other -- but they're
all switched simultaneously, so it sounds like one relay.

Here's a way to prove it. Auto-tune both antennas at a given frequency
(presumably both get close to 1:1). Then do a TUNE to check the SWR one
ANT 1. Now switch to ANT 2 and do a TUNE to check its SWR. It should
still be 1:1, because the relays *did* switch.

Another way to prove that the relays switched is to use the KAT3's "LC
SET" mode (in the menu). This is normally used to manually adjust LC
values for troubleshooting purposes, but you can also use it to check
the ATU's present LC settings:

   1. Set the KAT3 for AUTO mode and tune up both antennas.
   2. Set CONFIG:KAT3 to LC SET and exit the menu.
   3. Tap ATU TUNE: It'll show you the L and C values as well as
      where the 'C' is (CT = xmit side of the L-network, CA = ant side).
   4. Tap ATU TUNE to clear the LC display.
   5. Set CONFIG:KAT3 to AUTO and exit the menu.
   6. Tap ANT to switch to the other antenna, then repeat steps 2-5;
      you'll see a different LC value in effect.

We're also going to add multiple ATU LC storage segments per band.

73,
Wayne
N6KR

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[wayne burdick]

This is on the firmware list already. Sorry for not responding sooner
-- problems with e-mail today.

73,
Wayne
N6KR

David Cutter wrote:

> I agree completely
>
> David
> G3UNA
>
>
>>
>> I am one of the people who requested that the ATU active / bypass
>> settings
>> could be stored along with ANT 1 / 2.

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