Elecraft

Tuner Loss question

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Jobst Vandrey-2

Tuner Loss question

I have lots of data in the loss to be expected in Coax or Open wire when
running at higher SWR into a multiband antenna - however, I do NOT have
any real world data on the losses to be expected in a tuner system at
higher SWR.

So:

Are there any numbers available on what additional losses my Elecraft K3
(SN 5283) antenna tuner will experience when the SWR is high - say about
5:1 or higher when feeding a multiband antenna with 50 Ohm coax on 20
meters? Should I expect another 3 dB down in signal strength during
receive - and also Transmit? Or are the losses higher or lower then that?
Also, are the losses frequency dependent (like on coax) or are they the
same across the bands.

Thanks for any available data.

Jobst
AC0LP
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wa4ta

Re: Tuner Loss question

Why do you need to know the loss of the tuner? Put a power meter after the tuner and see what your rig is putting out.
Is this the type of chart you are looking for?http://www.packetradio.com/pdfzips/SWRvsPowerNwatts.pdf
It is not really the tuner that is causing the loss. It is more the feed line.
You can test this by using an external tuner and placing a watt meter both in front and behind the tuner and see what kind of loss you are getting.
Yes the tuner will have loss, but relatively negligible.

73 - Tom - wa4ta

> Date: Tue, 11 Feb 2014 11:47:19 -0600
> From: [hidden email]
> To: [hidden email]
> Subject: [Elecraft] Tuner Loss question
>
> I have lots of data in the loss to be expected in Coax or Open wire when
> running at higher SWR into a multiband antenna - however, I do NOT have
> any real world data on the losses to be expected in a tuner system at
> higher SWR.
>
> So:
>
> Are there any numbers available on what additional losses my Elecraft K3
> (SN 5283) antenna tuner will experience when the SWR is high - say about
> 5:1 or higher when feeding a multiband antenna with 50 Ohm coax on 20
> meters? Should I expect another 3 dB down in signal strength during
> receive - and also Transmit? Or are the losses higher or lower then that?
> Also, are the losses frequency dependent (like on coax) or are they the
> same across the bands.
>
> Thanks for any available data.
>
> Jobst
> AC0LP
> ______________________________________________________________
> 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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Wes (N7WS)

Re: Tuner Loss question

Sorry, but the chart is showing mismatch loss. When we use a tuner, we don't
suffer mismatch loss; we suffer tuner losses, which despite the claim(s), can be
appreciable.

N7WS

On 2/11/2014 2:36 PM, tom armour wrote:

> Why do you need to know the loss of the tuner? Put a power meter after the tuner and see what your rig is putting out.
> Is this the type of chart you are looking for?http://www.packetradio.com/pdfzips/SWRvsPowerNwatts.pdf
> It is not really the tuner that is causing the loss. It is more the feed line.
> You can test this by using an external tuner and placing a watt meter both in front and behind the tuner and see what kind of loss you are getting.
> Yes the tuner will have loss, but relatively negligible.
>
> 73 - Tom - wa4ta
>
>> Date: Tue, 11 Feb 2014 11:47:19 -0600
>> From: [hidden email]
>> To: [hidden email]
>> Subject: [Elecraft] Tuner Loss question
>>
>> I have lots of data in the loss to be expected in Coax or Open wire when
>> running at higher SWR into a multiband antenna - however, I do NOT have
>> any real world data on the losses to be expected in a tuner system at
>> higher SWR.
>>
>> So:
>>
>> Are there any numbers available on what additional losses my Elecraft K3
>> (SN 5283) antenna tuner will experience when the SWR is high - say about
>> 5:1 or higher when feeding a multiband antenna with 50 Ohm coax on 20
>> meters? Should I expect another 3 dB down in signal strength during
>> receive - and also Transmit? Or are the losses higher or lower then that?
>> Also, are the losses frequency dependent (like on coax) or are they the
>> same across the bands.
>>
>> Thanks for any available data.
>>
>> Jobst
>> AC0LP
>>

Phil Salas

Re: Tuner Loss question

In reply to this post by Jobst Vandrey-2

Check out the ARRL antenna tuner reviews. They all have loss measurements at up to 10:1 SWR for resistive loads. There are two Elecraft ARRL tuner reviews: KAT100 and KAT500.

Phil – AD5X
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Dick Dievendorff-4

Re: Tuner Loss question

In reply to this post by Wes (N7WS)

I'd recommend trying Dean Straw's (N6BV) excellent Transmission Line for
Windows (TLW), packaged with recent editions of the ARRL Antenna book. You
can make estimates of component Q and the tool estimates tuner losses for
various mismatches for different tuner configurations (L versus Pi versus
...). This is a modeling, not a measurement tool.

Phil, AD5X has included tuner loss information in his recent ATU review
articles in QST. Maybe there's something on his site of interest.
http://www.ad5x.com

See particularly
http://www.ad5x.com/images/Presentations/Remote%20Tuners.PDF for a
description of his measurement technique for tuner loss measurement.

73 de Dick, K6KR

-----Original Message-----
From: [hidden email]
[mailto:[hidden email]] On Behalf Of Wes (N7WS)
Sent: Tuesday, February 11, 2014 1:54 PM
To: [hidden email]
Subject: Re: [Elecraft] Tuner Loss question

Sorry, but the chart is showing mismatch loss. When we use a tuner, we
don't suffer mismatch loss; we suffer tuner losses, which despite the
claim(s), can be appreciable.

N7WS

On 2/11/2014 2:36 PM, tom armour wrote:
> Why do you need to know the loss of the tuner? Put a power meter after
the tuner and see what your rig is putting out.
> Is this the type of chart you are looking
> for?http://www.packetradio.com/pdfzips/SWRvsPowerNwatts.pdf
> It is not really the tuner that is causing the loss. It is more the feed
line.
> You can test this by using an external tuner and placing a watt meter both
in front and behind the tuner and see what kind of loss you are getting.

> Yes the tuner will have loss, but relatively negligible.
>
> 73 - Tom - wa4ta
>
>> Date: Tue, 11 Feb 2014 11:47:19 -0600
>> From: [hidden email]
>> To: [hidden email]
>> Subject: [Elecraft] Tuner Loss question
>>
>> I have lots of data in the loss to be expected in Coax or Open wire
>> when running at higher SWR into a multiband antenna - however, I do
>> NOT have any real world data on the losses to be expected in a tuner
>> system at higher SWR.
>>
>> So:
>>
>> Are there any numbers available on what additional losses my Elecraft
>> K3 (SN 5283) antenna tuner will experience when the SWR is high - say
>> about
>> 5:1 or higher when feeding a multiband antenna with 50 Ohm coax on 20
>> meters? Should I expect another 3 dB down in signal strength during
>> receive - and also Transmit? Or are the losses higher or lower then

that?
>> Also, are the losses frequency dependent (like on coax) or are they
>> the same across the bands.
>>
>> Thanks for any available data.
>>
>> Jobst
>> AC0LP
>>

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Wes (N7WS)

Re: Tuner Loss question

In reply to this post by Jobst Vandrey-2

You would need to know the unloaded Q of the capacitor(s) and Inductor(s) in the
circuit when a match is obtained and the complex impedance (not the SWR) of the
load to calculate the total loss. More than likely, it will be highly frequency
dependent.

N7WS.

On 2/11/2014 10:47 AM, Jobst Vandrey wrote:

> I have lots of data in the loss to be expected in Coax or Open wire when
> running at higher SWR into a multiband antenna - however, I do NOT have
> any real world data on the losses to be expected in a tuner system at
> higher SWR.
>
> So:
>
> Are there any numbers available on what additional losses my Elecraft K3
> (SN 5283) antenna tuner will experience when the SWR is high - say about
> 5:1 or higher when feeding a multiband antenna with 50 Ohm coax on 20
> meters? Should I expect another 3 dB down in signal strength during
> receive - and also Transmit? Or are the losses higher or lower then that?
> Also, are the losses frequency dependent (like on coax) or are they the
> same across the bands.
>
> Thanks for any available data.
>
> Jobst
> AC0LP
>

k6dgw

Re: Tuner Loss question

In reply to this post by Jobst Vandrey-2

On 2/11/2014 9:47 AM, Jobst Vandrey wrote:
> I have lots of data in the loss to be expected in Coax or Open wire when
> running at higher SWR into a multiband antenna - however, I do NOT have
> any real world data on the losses to be expected in a tuner system at
> higher SWR.

Obtain some sheet syrofoam and an indoor-outdoor remote reading
thermometer. Build a box from the styrofoam, enclose the tuner inside
it with the remote temp sensor and seal the box up. Record the
temperature. Fire up your TX into the tuner feeding the load of choice
and let the temperature stabilize. Be sure and ID every 10 mins.

Meanwhile, calculate the mass of the gas inside the box from its
dimensions, the barometric pressure when you sealed up the box, and the
Ideal Gas Law [PV=nRT]. Once the temperature stabilizes, you can
calculate how much of your TX energy went into heat inside the box. The
rest went up the coax. Calculate the loss from L[dB]=10*log[Ph/Po]
where Ph = power lost to heat and Po = TX power.

>
> So:
>
> Are there any numbers available on what additional losses my Elecraft K3
> (SN 5283) antenna tuner will experience when the SWR is high - say about
> 5:1 or higher when feeding a multiband antenna with 50 Ohm coax on 20
> meters? Should I expect another 3 dB down in signal strength during
> receive - and also Transmit? Or are the losses higher or lower then that?
> Also, are the losses frequency dependent (like on coax) or are they the
> same across the bands.

Seriously, the best way is to find a technical review of the tuner by
someone with all the appropriate test equipment. Intrinsically, every
tuner has loss that depends on many factors such as the Q of the
inductors, the L/C ratios required to match a given load, the complex
impedance presented to the tuner by the load, and the current phase of
the moon. However, it is very difficult to measure power in
non-resistive situations and the odds that the loads presented by your
multiband antenna are all resistive is right behind the odds you are
pregnant with twins. OK, I made up the part about the moon. I seem to
remember a QST series on tuner losses a few years ago, don't know if the
KAT3 was one of the ones tested.

In reality, it is what it is and if you found the losses to be high at
some combination, there's not much you can do about it save re-design
your antenna system [or get a different tuner].

73,

Fred K6DGW
- Northern California Contest Club
- CU in the 2014 Cal QSO Party 4-5 Oct 2014
- www.cqp.org

PS: I strongly urge the List Lurkers to get a little chuckle out of the
imperfect physics in the first graf and resist the urge to correct my
rendition. While I did, in 1959, manage to measure with pretty good
accuracy the efficiency of a 10KW FM Class C PA using real physics very
similar to my rendition above, I left out a lot in the tuner example.

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