K3 Internal Tuner Question

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K3 Internal Tuner Question

John Dziedziejko
I installed the KAT3 over the weekend and the construction and calibration
was successful. This evening I hooked everything back up to check reception,
tuning and swr. I have it set to AUTO, when I tap the ATU TUNE switch the
tuner does its thing and I read a 1.0:1 swr on the K3 meter. I have a
Palstar Wattmeter installed between the K3 and the antenna and for some
reason I am getting a high swr on the Palstar meter of 5:1 and don't
understand why. I have a multiband vertical antenna with a 4:1 Unun at the
base of the antenna. Am I missing something here?

A little hand holding would be appreciated.

Regards,

John W9QP



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Re: K3 Internal Tuner Question

Dick Dievendorff
The SWR displayed on the K3 is after the PA, but before the ATU. The external meter shows the SWR at the antenna, after the ATU.

Dick, K6KR

On Jan 1, 2012, at 20:12, "John Dziedziejko" <[hidden email]> wrote:

> I installed the KAT3 over the weekend and the construction and calibration
> was successful. This evening I hooked everything back up to check reception,
> tuning and swr. I have it set to AUTO, when I tap the ATU TUNE switch the
> tuner does its thing and I read a 1.0:1 swr on the K3 meter. I have a
> Palstar Wattmeter installed between the K3 and the antenna and for some
> reason I am getting a high swr on the Palstar meter of 5:1 and don't
> understand why. I have a multiband vertical antenna with a 4:1 Unun at the
> base of the antenna. Am I missing something here?
>
> A little hand holding would be appreciated.
>
> Regards,
>
> John W9QP
>
>
>
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
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Re: K3 Internal Tuner Question

Nate Bargmann
In reply to this post by John Dziedziejko
John, I'm not being flippant.  Please pick up a copy of Reflections III
by Walt Maxwell W2DU, published by CQ Comuunications.  The book covers a
lot of ground and will deepen your understanding of what you are rightly
seeing.

73, de Nate N0NB >>

--

"The optimist proclaims that we live in the best of all
possible worlds.  The pessimist fears this is true."

Ham radio, Linux, bikes, and more: http://www.n0nb.us
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Re: K3 Internal Tuner Question

John Lemay
In reply to this post by John Dziedziejko
John

I would struggle to explain this, but I'm quite certain that what you are
seeing is quite correct and nothing to worry about. The Palstar is showing
you the swr of the antenna and feedline. The K3 ATU is matching the
transmitter to this impedance. The ATU does not change the antenna
impedance.

Regards

John G4ZTR

-----Original Message-----
From: [hidden email]
[mailto:[hidden email]] On Behalf Of John Dziedziejko
Sent: 02 January 2012 04:13
To: [hidden email]
Subject: [Elecraft] K3 Internal Tuner Question

I installed the KAT3 over the weekend and the construction and calibration
was successful. This evening I hooked everything back up to check reception,
tuning and swr. I have it set to AUTO, when I tap the ATU TUNE switch the
tuner does its thing and I read a 1.0:1 swr on the K3 meter. I have a
Palstar Wattmeter installed between the K3 and the antenna and for some
reason I am getting a high swr on the Palstar meter of 5:1 and don't
understand why. I have a multiband vertical antenna with a 4:1 Unun at the
base of the antenna. Am I missing something here?

A little hand holding would be appreciated.

Regards,

John W9QP



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Re: K3 Internal Tuner Question

Joe Subich, W4TV-4

> You didn't say how much coax ran from the K3 to the Palstar. For an
> accurate comparison it should be zero (use an adapter) or at most an
> couple of inches of coax.

It the KAT3 is in use one can *never* compare the SWR displayed by the
K3 and that displayed by an external SWR bridge/wattmeter since there
will be an *impedance changing device* (the KAT3) between the K3's SWR
detector and the external SWR detector even if the length of coax is
zero.

73,

    ... Joe, W4TV


On 1/2/2012 11:27 AM, Ron D'Eau Claire wrote:

> John, that is a common question.
>
> The KAT3 is providing a 1:1 SWR between the KAT3 and the PA *inside* the K3
> so the K3's PA is 'seeing' the correct load. The KAT3 cannot change the
> impedance of the antenna presented to the ANT connector.
>
> You didn't say how much coax ran from the K3 to the Palstar. For an accurate
> comparison it should be zero (use an adapter) or at most an couple of inches
> of coax.
>
> You can replace the antenna with a good dummy load, and they should read
> much closer, although most dummy loads have some error as well, nor are SWR
> meters precision instruments; they don't need to be for efficient
> transmission line operation at H.F.
>
> Ron AC7AC
>
>
> -----Original Message-----
> From: [hidden email]
> [mailto:[hidden email]] On Behalf Of John Dziedziejko
> Sent: 02 January 2012 04:13
> To: [hidden email]
> Subject: [Elecraft] K3 Internal Tuner Question
>
> I installed the KAT3 over the weekend and the construction and calibration
> was successful. This evening I hooked everything back up to check reception,
> tuning and swr. I have it set to AUTO, when I tap the ATU TUNE switch the
> tuner does its thing and I read a 1.0:1 swr on the K3 meter. I have a
> Palstar Wattmeter installed between the K3 and the antenna and for some
> reason I am getting a high swr on the Palstar meter of 5:1 and don't
> understand why. I have a multiband vertical antenna with a 4:1 Unun at the
> base of the antenna. Am I missing something here?
>
> A little hand holding would be appreciated.
>
> Regards,
>
> John W9QP
>
>
>
> ______________________________________________________________
> 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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> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
>
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>
> The message was checked by ESET NOD32 Antivirus.
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> http://www.eset.com
>
>
>
>
> __________ Information from ESET NOD32 Antivirus, version of virus signature
> database 6761 (20120102) __________
>
> The message was checked by ESET NOD32 Antivirus.
>
> http://www.eset.com
>
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Re: K3 Internal Tuner Question

Rick WA6NHC
Let me see if I can correctly state, with clarity for all to understand so
this thread can die peacefully and we can move on (please?).

The K3 puts out power into an internal tuner (if installed) and then to an
SO-239 at the rear of the radio.  If the tuner is in bypass, the impedance
is very close to 50 ohm resistive at that connector.  In this case, any SWR
meter (bridge) downstream to the antenna will read the SWR (AT THAT POINT IN
THE FEEDLINE which may/not agree with the K3 reading).

If the tuner is NOT in bypass, the impedance at the same SO-239 will be
+-10:1 of 50 ohms.  Since any other SWR meter (bridge) between the K3 and
the antenna is probably NOT seeing the expected 50 Ohm impedance, the
reading of OTHER than the K3 meter will be called into question and more
than likely wrong.  

Repeating, when the internal tuner is used, the K3 meter is the only one
that is accurate.

Thank you and Happy New Year,
Rick wa6nhc



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Re: K3 Internal Tuner Question

Don Wilhelm-4
Rick,

Not quite --
Both SWR meters can be quite accurate - they are just not measuring the
same thing.

Imagine an external tuner - put an SWR meter on the input, and another
on the output -
Now make changes to the L and C in the tuner - note that the SWR meter
on the input is the only one that will change - the one on the output
will stay at the same SWR indication.  The "Antenna Tuner" does not
change anything in the antenna system beyond the tuner output - (yes, it
is not very well named) - what an antenna tuner does is add inductance
and capacity at one point in the feedline so that the impedance at its
input is close to 50 ohms resistive.  It transforms the impedance -- it
really does not "Tune" anything.

The same thing happens with the internal tuner in the K3 - the K3
indicates the same as the meter on the *input* in my example above - the
external meter acts as the one on the output, and it will not change no
matter how you change the settings of the ATU.

73,
Don W3FPR

On 1/2/2012 8:06 PM, Rick Bates wrote:

> Let me see if I can correctly state, with clarity for all to understand so
> this thread can die peacefully and we can move on (please?).
>
> The K3 puts out power into an internal tuner (if installed) and then to an
> SO-239 at the rear of the radio.  If the tuner is in bypass, the impedance
> is very close to 50 ohm resistive at that connector.  In this case, any SWR
> meter (bridge) downstream to the antenna will read the SWR (AT THAT POINT IN
> THE FEEDLINE which may/not agree with the K3 reading).
>
> If the tuner is NOT in bypass, the impedance at the same SO-239 will be
> +-10:1 of 50 ohms.  Since any other SWR meter (bridge) between the K3 and
> the antenna is probably NOT seeing the expected 50 Ohm impedance, the
> reading of OTHER than the K3 meter will be called into question and more
> than likely wrong.
>
> Repeating, when the internal tuner is used, the K3 meter is the only one
> that is accurate.
>
>
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Re: K3 Internal Tuner Question

Tom Azlin N4ZPT-2
In reply to this post by Rick WA6NHC
Not sure I understand this.

I did not think an SWR meter was supposed to work properly only when
seeing 50 ohms restive.

If the line is not flat it is terminated in to something other than the
feedline impedance, i.e. not 50 ohms restive in this discussion. I would
expect the SWR meter at some point in the feedline to be accurate under
those conditions because it is supposed to measure the standing wave
ratio of the feedline with respect to that 50 ohm resistive.

If I then have an antenna coupler in the radio that is matching the
transmitter to that non-50 ohm impedance why would the SWR meter change
to inaccurately measuring the SWR?   Putting the K3 into bypass or
letting it "tune" should not change the SWR measures at some point in
the feedline. The K3 may show 1:1 simply because it properly transformed
the line impedance to 50 ohms restive.

Perhaps I am missing something here. Sorry for continuing the discussion.

73, tom n4zpt

On 1/2/2012 8:06 PM, Rick Bates wrote:

> Let me see if I can correctly state, with clarity for all to understand so
> this thread can die peacefully and we can move on (please?).
>
> The K3 puts out power into an internal tuner (if installed) and then to an
> SO-239 at the rear of the radio.  If the tuner is in bypass, the impedance
> is very close to 50 ohm resistive at that connector.  In this case, any SWR
> meter (bridge) downstream to the antenna will read the SWR (AT THAT POINT IN
> THE FEEDLINE which may/not agree with the K3 reading).
>
> If the tuner is NOT in bypass, the impedance at the same SO-239 will be
> +-10:1 of 50 ohms.  Since any other SWR meter (bridge) between the K3 and
> the antenna is probably NOT seeing the expected 50 Ohm impedance, the
> reading of OTHER than the K3 meter will be called into question and more
> than likely wrong.
>
> Repeating, when the internal tuner is used, the K3 meter is the only one
> that is accurate.
>
> Thank you and Happy New Year,
> Rick wa6nhc

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Re: K3 Internal Tuner Question

Matthew Pitts
In reply to this post by John Dziedziejko
Tom,

All an antenna tuner does is show the radio the load it expects; the SWR will still be high at the output of the tuner, and an SWR meter in the coax at that output will show it as it actually is at that point, not as it is on the input of the tuner/output of the radio.

Matthew Pitts
N8OHU

Sent from my Wireless Device

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Re: K3 Internal Tuner Question

Tom Azlin N4ZPT-2
Thanks Matthew. I should not have spoken like that. Should just
have said the meter in the line would not change just because a radio
tuner transformed impedance to make the radio happy. 73, tom n4zpt

On 1/2/2012 9:11 PM, Matthew Pitts wrote:
> Tom,
>
> All an antenna tuner does is show the radio the load it expects; the
> SWR will still be high at the output of the tuner, and an SWR meter
> in the coax at that output will show it as it actually is at that
> point, not as it is on the input of the tuner/output of the radio.
>
> Matthew Pitts N8OHU

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Re: K3 Internal Tuner Question

Rick WA6NHC
In reply to this post by Tom Azlin N4ZPT-2
Hi Tom,

Ok, one more swing at it.

The "tuner" as Don states (and we agree), is transforming the 50 Ohm
impedance of the transmitter, into something that mates better with the
impedance of the antenna for (hopefully*) better transfer of energy to/from
the antenna.  There are similar circuits inside every radio to transfer the
energy between sections.  The proper term would be "impedance matching
circuit or device" but we're taught (and stuck with) 'tuner'.

Now, using our beloved K3 in this example:
Tuner in bypass produces ~50 Ohm impedance at the back of the K3.
Tuner in use produces an impedance of somewhere between 5-500 Ohms at the
back of the same K3.  You don't know what that impedance is.

The SWR meter is expecting (because transmitters are usually set to) 50 Ohm
impedance.  If that impedance is off, the meter reading is probably wrong.
Sure, it will read something, but the reading is worthless (even as a power
meter) because of the mismatch.  The amount of error is dependent on the
amount of mismatch (which we don't know).  So you're correct, that they are
only accurate at 50 Ohm impedance (give or take a small percentage).

This is why you put the SWR meter between the output of a known impedance
(50 Ohm coming out of the transmitter) and the matching device (50 Ohm
input).  As the device changes LC values to compensate for (match) the
reactance(s) of the antenna, the standing wave at the meter is reduced.
This is how you can tell that the matching device is transferring more
energy to the antenna (the reactance is 'tuned' out).

As Don also accurately stated, it doesn't make the antenna work ANY better,
but it does transfer more energy TO the antenna (disregarding tuner and line
losses) because of better matching.

And note that I most carefully said that the meter makes a reading AT THAT
POINT IN THE FEEDLINE.  If you add/subtract patch cables to an external
meter (or alter feedline length), your reading may very well be different.
The 'trap' that many hams fall into is that the feedline is treated as a
'hose' between transmitter and antenna.  It isn't; but is PART of the entire
circuit (it is not passive).  Which leads to your next comment.

What you were referring to was that the impedance of the antenna is best
read (is duplicated) at half wave intervals on the feedline (ignoring the
added feedline reactance).  Most hams simply cut to convenient lengths (me
too) because we're using multiple band antennas (or at least feeding them
that way) and we tend to let the 'tuner' take up any slack (or ignore the
losses).  This is why the K3 meter, sensing at the transmitter output and
before the internal tuner, is the best place to measure SWR.  The tuner
matches THAT point in the feedline system for best transfer of energy.

The bottom line is simple.  If you are using a matching device (a tuner) the
ONLY place that a SWR meter will accurately read what you expect, is after
the amplifier and before the matching device.   This should also show you
why short patch cables should be used to attach the SWR meter to the
transmitter, to minimize error from reading at a random point in the feed
(it's more accurate AT the transmitter).

Does that help?

Rick WA6NHC

* I threw in this caveat because I once had a very nice, high power,
homebrew 'tuner' that I could feed with the 200 watt transmitter and get a
'perfect match' with *nothing* delivered to the attached end fed random
wire.  The 'tuner' simply converted it into heat.  If I retuned using a
different LC combination, I was heard.  Don't ask what type etc., because I
don't remember and stupidly sold it over 30 years ago.  :o(

 
-----Original Message-----
From: Tom Azlin N4ZPT

Not sure I understand this.

I did not think an SWR meter was supposed to work properly only when
seeing 50 ohms restive.

If the line is not flat it is terminated in to something other than the
feedline impedance, i.e. not 50 ohms restive in this discussion. I would
expect the SWR meter at some point in the feedline to be accurate under
those conditions because it is supposed to measure the standing wave
ratio of the feedline with respect to that 50 ohm resistive.

If I then have an antenna coupler in the radio that is matching the
transmitter to that non-50 ohm impedance why would the SWR meter change
to inaccurately measuring the SWR?   Putting the K3 into bypass or
letting it "tune" should not change the SWR measures at some point in
the feedline. The K3 may show 1:1 simply because it properly transformed
the line impedance to 50 ohms restive.

Perhaps I am missing something here. Sorry for continuing the discussion.

73, tom n4zpt

On 1/2/2012 8:06 PM, Rick Bates wrote:
> Let me see if I can correctly state, with clarity for all to understand so
> this thread can die peacefully and we can move on (please?).
>
> The K3 puts out power into an internal tuner (if installed) and then to an
> SO-239 at the rear of the radio.  If the tuner is in bypass, the impedance
> is very close to 50 ohm resistive at that connector.  In this case, any
SWR
> meter (bridge) downstream to the antenna will read the SWR (AT THAT POINT
IN

> THE FEEDLINE which may/not agree with the K3 reading).
>
> If the tuner is NOT in bypass, the impedance at the same SO-239 will be
> +-10:1 of 50 ohms.  Since any other SWR meter (bridge) between the K3 and
> the antenna is probably NOT seeing the expected 50 Ohm impedance, the
> reading of OTHER than the K3 meter will be called into question and more
> than likely wrong.
>
> Repeating, when the internal tuner is used, the K3 meter is the only one
> that is accurate.
>
> Thank you and Happy New Year,
> Rick wa6nhc


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Re: K3 Internal Tuner Question

Buck - k4ia
In reply to this post by Tom Azlin N4ZPT-2
Well here's one for you:

My setup is K3 to wattmeter to dummy load.

The K3 says 100w
If the external wattmeter is:
MFJ 949E tuner/SWR meter (tuner out of circuit) it says 100w
cheapo Radio Shack SWR meter 100w
LP 100A digital wattmeter says 70 watts
Elecraft W2 says 70 watts

Yes, I have run the transmitter calibration routine in the K3 Utility
program.  SWR in all three cases is nominal 1:1

The result is the same to a real antenna although the SWR is not 1:1

What could be causing the external-sensor type wattmeters to read low?

Buck
k4ia
K3 # 101

On 1/2/2012 10:14 PM, Ron D'Eau Claire wrote:

> Quite right.
>
> There a couple of impedance transformations that occur between the
> collectors (or plates) of the power amplifiers and the antenna. The first is
> done by the output filters. In modern rigs, they are fixed tuned and
> designed in common Ham rigs to convert the impedance at the collectors to 50
> ohms, resistive.
>
> If your antenna presents that impedance, no further conversion is necessary.
> But many antennas don't.
>
> In the "old" days the output network was adjustable and we simply did the
> necessary adjustments and all was good.
>
> Nowadays, with fixed tuned amplifier output networks, we need another
> matching network to handle the conversion when the antenna doesn't present a
> 50 ohms resistive load.
>
> Enter the "antenna tuner" that converts what the antenna shows to the 50
> ohms needed by the output filter. The built in SWR meter displays the SWR on
> the link between the tuner and the output filter.
>
> Ron AC7AC
>
> -----Original Message-----
> From: [hidden email]
> [mailto:[hidden email]] On Behalf Of Tom Azlin N4ZPT
> Sent: Monday, January 02, 2012 6:19 PM
> To: [hidden email]
> Subject: Re: [Elecraft] K3 Internal Tuner Question
>
> Thanks Matthew. I should not have spoken like that. Should just
> have said the meter in the line would not change just because a radio
> tuner transformed impedance to make the radio happy. 73, tom n4zpt
>
> On 1/2/2012 9:11 PM, Matthew Pitts wrote:
>> Tom,
>>
>> All an antenna tuner does is show the radio the load it expects; the
>> SWR will still be high at the output of the tuner, and an SWR meter
>> in the coax at that output will show it as it actually is at that
>> point, not as it is on the input of the tuner/output of the radio.
>>
>> Matthew Pitts N8OHU
>
> ______________________________________________________________
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Re: K3 Internal Tuner Question

Don Wilhelm-4
Buck,

You are like the man with 2 (or more) watches who never knew what time
it was!

Was your LP-100A calibrated to NIST traceable standards (Larry's
calibration tools)?
If the answer is yes, I would use the LP-100A as the "standard" to
calibrate the K3 wattmeter (see instructions in the manual).
After having calibrated the internal wattmeter in the K3, then run the
TX gain calibration with K3 Utility.

73,
Don W3FPR

On 1/3/2012 8:50 AM, Buck k4ia wrote:

> Well here's one for you:
>
> My setup is K3 to wattmeter to dummy load.
>
> The K3 says 100w
> If the external wattmeter is:
> MFJ 949E tuner/SWR meter (tuner out of circuit) it says 100w
> cheapo Radio Shack SWR meter 100w
> LP 100A digital wattmeter says 70 watts
> Elecraft W2 says 70 watts
>
> Yes, I have run the transmitter calibration routine in the K3 Utility
> program.  SWR in all three cases is nominal 1:1
>
> The result is the same to a real antenna although the SWR is not 1:1
>
> What could be causing the external-sensor type wattmeters to read low?
>
> Buck
> k4ia
> K3 # 101
>
> On 1/2/2012 10:14 PM, Ron D'Eau Claire wrote:
>> Quite right.
>>
>> There a couple of impedance transformations that occur between the
>> collectors (or plates) of the power amplifiers and the antenna. The first is
>> done by the output filters. In modern rigs, they are fixed tuned and
>> designed in common Ham rigs to convert the impedance at the collectors to 50
>> ohms, resistive.
>>
>> If your antenna presents that impedance, no further conversion is necessary.
>> But many antennas don't.
>>
>> In the "old" days the output network was adjustable and we simply did the
>> necessary adjustments and all was good.
>>
>> Nowadays, with fixed tuned amplifier output networks, we need another
>> matching network to handle the conversion when the antenna doesn't present a
>> 50 ohms resistive load.
>>
>> Enter the "antenna tuner" that converts what the antenna shows to the 50
>> ohms needed by the output filter. The built in SWR meter displays the SWR on
>> the link between the tuner and the output filter.
>>
>> Ron AC7AC
>>
>> -----Original Message-----
>> From: [hidden email]
>> [mailto:[hidden email]] On Behalf Of Tom Azlin N4ZPT
>> Sent: Monday, January 02, 2012 6:19 PM
>> To: [hidden email]
>> Subject: Re: [Elecraft] K3 Internal Tuner Question
>>
>> Thanks Matthew. I should not have spoken like that. Should just
>> have said the meter in the line would not change just because a radio
>> tuner transformed impedance to make the radio happy. 73, tom n4zpt
>>
>> On 1/2/2012 9:11 PM, Matthew Pitts wrote:
>>> Tom,
>>>
>>> All an antenna tuner does is show the radio the load it expects; the
>>> SWR will still be high at the output of the tuner, and an SWR meter
>>> in the coax at that output will show it as it actually is at that
>>> point, not as it is on the input of the tuner/output of the radio.
>>>
>>> Matthew Pitts N8OHU
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> ______________________________________________________________
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>
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