Elecraft

Tuner efficiency question

Classic

List

Threaded

27 messages Options

W7RY

Re: Tuner efficiency question

Wow... This chap has quite a setup! And he's very talented! Take a look at
some of those construction projects!

Very nice indeed!
73
Jim W7RY

At 01:21 PM 5/13/2005, Stephen W. Kercel wrote:

>Stuart
>
>It was a year or two back that I saw them. It may well be the case that
>they are discontinued. They were way out of the price range of the typical ham.
>
>However, these Web pages still work.
>
>http://www.hewezi.com/bal_tuner.html
>
>http://www.dj2hz.de/
>
>If you're really curious, get in touch with DJ2HZ
>
>73,
>
>Steve
>AA4AK
>
>At 01:59 PM 5/13/2005 -0500, you wrote:
>>My understanding, from L. B. Cebik, was the German balanced tuners were
>>discontinued. I could not find them by Google search.
>>-Stuart
>>K5KVH
>
>
>_______________________________________________
>Elecraft mailing list
>Post to: [hidden email]
>You must be a subscriber to post to the list.
>Subscriber Info (Addr. Change, sub, unsub etc.):
>http://mailman.qth.net/mailman/listinfo/elecraft
>
>Help: http://mailman.qth.net/subscribers.htm
>Elecraft web page: http://www.elecraft.com

W7RY

RE: Tuner efficiency question

In reply to this post by al_lorona

There is a fellow here in the NW that builds link coupled tuners. Pat
Buller, W7RQT.

They are quite well made and look great. His email is shown on www.qrz.com

73
Jim W7RY

ConAt 09:30 AM 5/13/2005, [hidden email] wrote:

> > ...
> > Contrary to popular belief, balun loss is not the largest
> > contributing factor, and if properly designed, makes
> > little difference whether it is placed on the input or the
> > output. Charles Green W1CG has done a lot of work
> > on balun loss and reports that the loss is actually
> > quite low (even when their design impedance is
> > severly mismatched).
> >
> > My bottom line conclusion here is that we pay a price
> > in efficiency for the convenience of compactness and
> > a large matching range.
>
>Yes, we most certainly do. Too many of us care only about the automatic
>aspect of these compact tuners, and we give up really efficient tuner
>operation. Tuners have to be really large to be really good. The
>components have to be large and the enclosures have to be large. But
>because many people don't like large boxes on their operating tables, and
>because they would rather not twiddle knobs, they go to these small,
>sometimes lossy autotuners. As long as they understand what they are
>giving up by doing this, it's cool.
>
>However, balun loss isn't the only important factor and may not even be
>the most important factor. The balun's primary purpose is to convert to a
>balanced two-wire system, and in order to preserve the antenna pattern and
>keep the feedline from radiating, it has to provide equal currents in each
>leg of the feedline. In order to be effective at this, the balun's
>impedance has to be large compared to the antenna's input impedance. When
>baluns in tuners have to look into very high impedances, they stop acting
>as baluns. You may be happy that a particular balun doesn't have a lot of
>loss, but you would be very unhappy to learn that that same balun isn't
>doing it's job as a balun anymore. Under these conditions, who knows what
>the antenna pattern is.
>
>Using a balanced tuner gets you part of the way to a highly efficient
>antenna system; the other half of the journey is to use a balun-less
>design that attains true balance no matter what the antenna/feedline
>conditions are. I have found this possible only by homebrewing such a tuner.
>
>I don't know if you've ever seen the Annecke tuner on L. B. Cebik's web
>site: http://www.cebik.com/link/link.html . It was the best hope we've
>had to seeing a link-coupled tuner like the old Johnson Matchbox, and many
>folks were expecting it to go back into production, but the person who
>bought the rights to the design has decided not to pursue the manufacture
>of the tuner at this time. Too bad. We'll just have to keep building them
>ourselves.
>
>Al W6LX
>
>
>
>
>
>
>
>
>_______________________________________________
>Elecraft mailing list
>Post to: [hidden email]
>You must be a subscriber to post to the list.
>Subscriber Info (Addr. Change, sub, unsub etc.):
> http://mailman.qth.net/mailman/listinfo/elecraft
>
>Help: http://mailman.qth.net/subscribers.htm
>Elecraft web page: http://www.elecraft.com

EricJ-2

RE: Tuner efficiency question

In reply to this post by W7RY

I like the "QRP Balanced Antenna Tuner" rated at only 500W.

Eric
KE6US

-----Original Message-----
From: elecraft-bounces+eric_csuf=[hidden email]
[mailto:elecraft-bounces+eric_csuf=[hidden email]] On Behalf Of
Jim W7RY
Sent: Friday, May 13, 2005 4:32 PM
To: [hidden email]
Subject: Re: [Elecraft] Tuner efficiency question

Wow... This chap has quite a setup! And he's very talented! Take a look at
some of those construction projects!

Very nice indeed!
73
Jim W7RY

At 01:21 PM 5/13/2005, Stephen W. Kercel wrote:
>Stuart
>
>It was a year or two back that I saw them. It may well be the case that
>they are discontinued. They were way out of the price range of the typical
ham.

>
>However, these Web pages still work.
>
>http://www.hewezi.com/bal_tuner.html
>
>http://www.dj2hz.de/
>
>If you're really curious, get in touch with DJ2HZ
>
>73,
>
>Steve
>AA4AK
>
>At 01:59 PM 5/13/2005 -0500, you wrote:
>>My understanding, from L. B. Cebik, was the German balanced tuners
>>were discontinued. I could not find them by Google search.
>>-Stuart
>>K5KVH
>
>
>_______________________________________________
>Elecraft mailing list
>Post to: [hidden email]
>You must be a subscriber to post to the list.
>Subscriber Info (Addr. Change, sub, unsub etc.):
>http://mailman.qth.net/mailman/listinfo/elecraft
>
>Help: http://mailman.qth.net/subscribers.htm
>Elecraft web page: http://www.elecraft.com

_______________________________________________
Elecraft mailing list
Post to: [hidden email]
You must be a subscriber to post to the list.
Subscriber Info (Addr. Change, sub, unsub etc.):
http://mailman.qth.net/mailman/listinfo/elecraft

Help: http://mailman.qth.net/subscribers.htm
Elecraft web page: http://www.elecraft.com
_______________________________________________
Elecraft mailing list
Post to: [hidden email]
You must be a subscriber to post to the list.
Subscriber Info (Addr. Change, sub, unsub etc.):
http://mailman.qth.net/mailman/listinfo/elecraft

Help: http://mailman.qth.net/subscribers.htm
Elecraft web page: http://www.elecraft.com

N2EY

Re: Tuner efficiency question

In reply to this post by Parker Buckley

In a message dated 5/13/05 12:51:01 PM Eastern Daylight Time, [hidden email]
writes:

> Many QRP operators assume that a tuner used for QRP can
> be small because one doesn't need the power-handling capability of a larger
> tuner. However, if a tuner has x db loss, then that loss will reduce the
> strength of a received signal by x db whether the signal is transmitted at 5
> or
> 500 watts!
>
>

That's true but it doesn't mean good tuners must be big.

The lossiest element in most tuners is the inductor. If an inductor has high
Q, then by definition it has low loss.

Power-handling capability is a related but different thing.It involves the
ability to withstand high voltage if necessary, and to dissipate a certain
amount of power. A high Q coil doesn't necessarily have a high power handling
capacity, and vice versa.

73 de Jim, N2EY

_______________________________________________
Elecraft mailing list
Post to: [hidden email]
You must be a subscriber to post to the list.
Subscriber Info (Addr. Change, sub, unsub etc.):
http://mailman.qth.net/mailman/listinfo/elecraft

Help: http://mailman.qth.net/subscribers.htm
Elecraft web page: http://www.elecraft.com

Bill Coleman-2

Re: Tuner efficiency question

In reply to this post by John, KI6WX

On May 13, 2005, at 12:40 AM, John, KI6WX wrote:

> At high power, an inefficient tuner can generate significant
> amounts of heat, which can destroy components. A 1kW transmitter
> into a 70% efficient tuner will generate 300 watts of heat in the
> tuner.

This is why I tend to disbelieve tuner efficiency figures. From the
QST tests, there seem to be a lot of tuners than have losses greater
than 10% -- yet there is no evidence that any of these tuners heat up
appreciably! At 1 kW, a 10% loss is 100 watts -- imagine how hot a
tuner enclosure would get if you had a 100 watt light bulb inside it.

Even at 100 watts, 10% loss is 10 watts. That's still enough to
induce a few degree change in a small enclosure.

Bill Coleman, AA4LR, PP-ASEL Mail: [hidden email]
Quote: "Not within a thousand years will man ever fly!"
-- Wilbur Wright, 1901

_______________________________________________
Elecraft mailing list
Post to: [hidden email]
You must be a subscriber to post to the list.
Subscriber Info (Addr. Change, sub, unsub etc.):
http://mailman.qth.net/mailman/listinfo/elecraft

Help: http://mailman.qth.net/subscribers.htm
Elecraft web page: http://www.elecraft.com

Bill Coleman-2

Re: Tuner efficiency question

In reply to this post by Stephen W. Kercel

On May 13, 2005, at 9:32 AM, Stephen W. Kercel wrote:

> Comment on baluns: If you drive a ferrite core to saturation, it
> will overheat.

True.

> Once the core overheats, the inductance changes and you lose your
> match (quite severely, in my experience).

In order to change the inductance permanently, it must reach the
Curie temperature. The inductance will change much at a much lower
temperature than this, but the effects aren't lasting.

> It doesn't really take much to do it; a few minutes of normal CW
> operating with 100 watts into a 5:1 SWR on 20 meters will do the
> trick for me. You are much more likely to drive a balun core into
> saturation on the high SWR output of a tuner than on the low SWR
> input of the tuner.

Note that a normal current-type balun feeding a non-pathological
antenna (one that has made a reasonable attempt to be balanced) will
show little or no flux on the core. The object of the current-type
balun is to discourage current from flowing by creating a high-
impedance path -- if there's high impedance there's little current
and therefore less chance of heating.

Bill Coleman, AA4LR, PP-ASEL Mail: [hidden email]
Quote: "Not within a thousand years will man ever fly!"
-- Wilbur Wright, 1901

_______________________________________________
Elecraft mailing list
Post to: [hidden email]
You must be a subscriber to post to the list.
Subscriber Info (Addr. Change, sub, unsub etc.):
http://mailman.qth.net/mailman/listinfo/elecraft

Help: http://mailman.qth.net/subscribers.htm
Elecraft web page: http://www.elecraft.com

Parker Buckley

RE: Tuner efficiency question

In reply to this post by Bill Coleman-2

I still don't know what to think. I came home from Hamvention today with
the tiny T1 tuner for my K2, based more on convenience of installation and
ability to use it with other rigs and portability. If I eventually want an
auto tuner for higher power, I'll go through all this again, I guess.
Meanwhile, I'll keep the Hallicrafters connected to the Palstar tuner.

Hey, it was worth the price of the tuner, just to meet Don at the Elecraft
booth!

Parker

-----Original Message-----
From: Bill Coleman [mailto:[hidden email]]
Sent: Friday, May 20, 2005 2:24 PM
To: John, KI6WX
Cc: Don; Parker Buckley; [hidden email]
Subject: Re: [Elecraft] Tuner efficiency question

On May 13, 2005, at 12:40 AM, John, KI6WX wrote:

> At high power, an inefficient tuner can generate significant
> amounts of heat, which can destroy components. A 1kW transmitter
> into a 70% efficient tuner will generate 300 watts of heat in the
> tuner.

This is why I tend to disbelieve tuner efficiency figures. From the
QST tests, there seem to be a lot of tuners than have losses greater
than 10% -- yet there is no evidence that any of these tuners heat up
appreciably! At 1 kW, a 10% loss is 100 watts -- imagine how hot a
tuner enclosure would get if you had a 100 watt light bulb inside it.

Even at 100 watts, 10% loss is 10 watts. That's still enough to
induce a few degree change in a small enclosure.

Bill Coleman, AA4LR, PP-ASEL Mail: [hidden email]
Quote: "Not within a thousand years will man ever fly!"
-- Wilbur Wright, 1901

_______________________________________________
Elecraft mailing list
Post to: [hidden email]
You must be a subscriber to post to the list.
Subscriber Info (Addr. Change, sub, unsub etc.):
http://mailman.qth.net/mailman/listinfo/elecraft

Help: http://mailman.qth.net/subscribers.htm
Elecraft web page: http://www.elecraft.com