Homebrew tuners
 

Seems like a lot of hams with limited resources are still compelled
to operate on many bands with just a long wire and a tuner.
The wire is inexpensive but the tuners are not. Thus my present
project.
I was given a Palomar enginnering balun with 5 female connenection
which by selection can match a antenna in steps from 5 ohms to over
450 ohms
in a series of steps. I am presently rigging it up so that all
steps can be switched thru remotely by a single motor. The switching
arrangement
is the main challenge since inexpensive means simple.
Now I have not measured losses of the balun before hand because the
switching
challenge is what is driving me.
Anybody have any thoughts about what I should expect from this
balun other than knowing that it is not a tuner as is generally known
since
it does not have the ability to obtain the priceless 1:1 condition
that so many desire?
Regards
Art

Art, are you sure you have a balun? Your description sounds like a tapped
r-f transformer.

A balun, of course, is completely different from a transformer in that it is
a "transmission line transformer" which is made of short transmission line
sections instead of "windings."

If a balun is made with line sections of Zo, then the load must be an
appropriate multiple of Zo and purely resistive for the balun to function
properly.

Usually it is best to let a balun do the current steering and keep the outer
braid of the coax "clean" and do the impedance matching elsewhere, as in a
tuner.

Just a thought . . .

--
73/72, George
Amateur Radio W5YR - the Yellow Rose of Texas
Fairview, TX 30 mi NE of Dallas in Collin county EM13QE
"In the 57th year and it just keeps getting better!"






"Art Unwin KB9MZ" wrote in message
m...
Seems like a lot of hams with limited resources are still compelled
to operate on many bands with just a long wire and a tuner.
The wire is inexpensive but the tuners are not. Thus my present
project.
I was given a Palomar enginnering balun with 5 female connenection
which by selection can match a antenna in steps from 5 ohms to over
450 ohms
in a series of steps. I am presently rigging it up so that all
steps can be switched thru remotely by a single motor. The switching
arrangement
is the main challenge since inexpensive means simple.
Now I have not measured losses of the balun before hand because the
switching
challenge is what is driving me.
Anybody have any thoughts about what I should expect from this
balun other than knowing that it is not a tuner as is generally known
since
it does not have the ability to obtain the priceless 1:1 condition
that so many desire?
Regards
Art

Yes George, I mispoke, you are correct
It says in very large letters on it " TRANSFORMER"
Since transformers are touted as being efficient
I was wondering how it would compare with
the normal tuner. Half of the challenge for me
was to come up with an inexpensive switching
system where the input was stationary while the rest
were switched thru and then repeated for the next
input e.t.c. With that being solved I look forward
to finishing and then playing with it
Regards
Art



"George, W5YR" wrote in message ...
Art, are you sure you have a balun? Your description sounds like a tapped
r-f transformer.

A balun, of course, is completely different from a transformer in that it is
a "transmission line transformer" which is made of short transmission line
sections instead of "windings."

If a balun is made with line sections of Zo, then the load must be an
appropriate multiple of Zo and purely resistive for the balun to function
properly.

Usually it is best to let a balun do the current steering and keep the outer
braid of the coax "clean" and do the impedance matching elsewhere, as in a
tuner.

Just a thought . . .

--
73/72, George
Amateur Radio W5YR - the Yellow Rose of Texas
Fairview, TX 30 mi NE of Dallas in Collin county EM13QE
"In the 57th year and it just keeps getting better!"






"Art Unwin KB9MZ" wrote in message
m...
Seems like a lot of hams with limited resources are still compelled
to operate on many bands with just a long wire and a tuner.
The wire is inexpensive but the tuners are not. Thus my present
project.
I was given a Palomar enginnering balun with 5 female connenection
which by selection can match a antenna in steps from 5 ohms to over
450 ohms
in a series of steps. I am presently rigging it up so that all
steps can be switched thru remotely by a single motor. The switching
arrangement
is the main challenge since inexpensive means simple.
Now I have not measured losses of the balun before hand because the
switching
challenge is what is driving me.
Anybody have any thoughts about what I should expect from this
balun other than knowing that it is not a tuner as is generally known
since
it does not have the ability to obtain the priceless 1:1 condition
that so many desire?
Regards
Art

Define 'Efficient' before you engage in this discussion.

"When I was a youngster, back in the olden golden days, transformer
efficiencies exceeded 98%, but that was for 60 Cycle [olden days
language] power distribution systems."

H U G E G R I N

Deacon Dave, W1MCE
+ + +

W5DXP wrote:

Art Unwin KB9MZ wrote:

Since transformers are touted as being efficient
I was wondering how it would compare with
the normal tuner.


Who touts transformers as being efficient? And efficient
compared to what?

Dave Shrader wrote:
Define 'Efficient' before you engage in this discussion.

OK, let's say as efficient as a transmission line transformer
over an entire range of frequencies. I don't think you will
find a normal transformer that is as efficient as a transmission
line transformer over the entire HF frequency range. But I could
be wrong.
--
73, Cecil http://www.qsl.net/w5dxp



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Cecil, if I go back in time a long way, to the days of transformer
design, I recall that core loss increased as an exponential of
frequency. The exponential was greater than '1.2' and less than '2.0'.

Now, magnetic materials have changed, since the invention of the wheel,
but I still suspect that losses in magnetic materials are exponential,
even in new materials.

So, in a transformer I would expect core loss to increase exponentially
from 1.8 to 29.7 MHz.

In a balun, well I don't know!

Shortly after the invention of the wheel I came into the ownership of a
B&W air wound balun rated at 250 watts continuous that I used for over
35 years. I dumped it as part of the move from Massachusetts to New
Hampshire. That was DUMB! But, using air instead of magnetic material
certainly minimized losses grin.

Back to the Modern Age. How efficient is a transmission line
transformer? [TBD %] Can you quantify a suitable number or will it
remain a qualitative statement?

Deacon Dave, W1MCE
+ + +

W5DXP wrote:
Dave Shrader wrote:

Define 'Efficient' before you engage in this discussion.


OK, let's say as efficient as a transmission line transformer
over an entire range of frequencies. I don't think you will
find a normal transformer that is as efficient as a transmission
line transformer over the entire HF frequency range. But I could
be wrong.

Dave Shrader wrote:
Back to the Modern Age. How efficient is a transmission line
transformer? [TBD %] Can you quantify a suitable number or will it
remain a qualitative statement?

Looking at some of the graphs in Jerry Sevick's book, _Transmission_
Line_Transformers_, it looks like about .05 dB maximum loss from 3
to 30 MHz. Note that figure is for perfectly matched resistive loads.

A transmission line transformer carries a high flux density for common
mode but not for differential mode. An ordinary transformer carries
a high flux density for differential mode. That's got to make a
difference.
--
73, Cecil http://www.qsl.net/w5dxp



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For design, frequency-response, insertion-loss of 4:1 impedance ratio,
transmission line HF transformers (voltage Baluns), download program BALUN4
from website below -
---
=======================
Regards from Reg, G4FGQ
For Free Radio Design Software
go to http://www.g4fgq.com
=======================

Given that a 1dB change is NOT SUSPOSED to be noticed (without a meter, in
hearing, sight, ect. ), anyhow, Just what would be the Noticeable effect of
/ = .1 dB in the real world ? Would , say, 2/10's really kill you, or
1/100th dB extra get you that last DXCC country? As I say, am very cynical
when ANYTHING gets into these kinds of numbers! Jim NN7K




KB7QHC wrote:
-------------------------------------------------
50:12.5 Ohm with an insertion loss of around 0.1dB or less over the
interval of 100KHz to 30MHz.
AND THAT IS NOT THE BEST EXAMPLE OF LOW LOSS!
73's Richard Clark, KB7QHC