home made balancing transformer Qs

home made balancing transformer Qs

Post by Andrew Rimel » Tue, 12 Oct 1999 04:00:00

Any tips on winding my own 3.5:1 balancing transformer?

Can I take a miniture mains transformer, rip out all the wire and
wind my own?

Is 35 and 10 turns ok or do I need to go to the hassle of
increasing that to set up a big enough magnetic field?

Do I have to use varnished copper wire - I have a supply
of very thin PVC coated wire, is that OK?

Andy

 
 
 

home made balancing transformer Qs

Post by AA1L » Tue, 12 Oct 1999 04:00:00




Quote:> Any tips on winding my own 3.5:1 balancing transformer?

> Can I take a miniture mains transformer, rip out all the wire and
> wind my own?

> Is 35 and 10 turns ok or do I need to go to the hassle of
> increasing that to set up a big enough magnetic field?

> Do I have to use varnished copper wire - I have a supply
> of very thin PVC coated wire, is that OK?

> Andy

Hi Andy, welcome to alt.baluns.  You will get more info than you ever
wanted by saying the magic word, "balun" on this NG!

The performance of low frequecy 50-60Hz power supply magnetic materials
at megahertz frequencies is not appropriate to perform efficient
balanced-to-unbalanced transformation by flux linkage alone.  So other
materials and circuits are used, such as building "transmission line
transformers" with cores made of ferrite (a high frequency high mu
material) and using windings of twisted pairs of primaries and
secondaries.

You can make one that will be very broadband by using a ferrite rod from
an a.m. radio.  Obtaining impedance transformer ratios other than N^2
where N is integer is difficult with these circuits, but a 4:1 ratio is
easily made by the following:

        A B
        | |
        | |
     || C C
     || C C
     || C C
     || C C
     || C C
     || C C
        | |
        | |
        C D

This poor excuse for a circuit is supposed to indicate that you make two
windings in parallel, of number 22 wire close spaced next to each other
or even twisted together (not critical) and fill up the whole ferrite
rod with it.  This will be around 30 turns or so.  Connect nodes B and
C.  For unbalanced Z ohm input (A=center conductor, B=Ground), 4Z
balanced output is available at terminals C and D.

Here are some references, scoffed from
http://sites.penton.com/mwrf/index.htm  :

TRANSFORMER TYPE BALUN REFERENCES BY Enzo Carpentieri:

1. C.L. Ruthroff, "Some Broadband Transformers," Proceedings of the IRE,
August 1959, pp. 1337-1342.

2. L.D. Abrie, The Design of Impedance-Matching Networks for
Radio-Frequency and Microwave Amplifiers, Artech House, 1985.

3. Y. Shimada, "Input-Impedance Analysis of a 1:1 Balun," IEEE
Transactions on Microwave Theory and Techniques, May 1970.

4. E. Rotholz, "Transmission-Line Transformers," IEEE Transactions on
Microwave Theory and Techniques, April 1981.

5. O. Pitzalis, "Practical Design Information for Broadband
Transmission-Line Transformers," Proceedings of the IRE, 1968.

6. D. Myer, "Equal-Delay Networks Match Impedances Over Wide
Bandwidths," Microwaves & RF, April 1990, pp. 179-188.

 FOR FURTHER READING

Grossner, Transformers for Electronic Circuits, 2nd ed., McGraw-Hill,
1983.

K.B. Niclas, R.R. Pereira, and A.P. Chang, "Transmission Lines
Accurately Model Autotransformers," Microwaves & RF, November 1992, pp.
67-76.

J. Sevick, Transmission-Line Transformers, 2nd ed., American Radio Relay
League, 1990.

C.W. Allen and H.L. Krauss, "Wideband Rotary Transformer--Unbalanced
Current Analysis," Proceedings of the IEEE, February 1977.

American Radio Relay League, The ARRL Handbook for Radio Amateurs, 69th
ed., 1992.

ENZO CARPENTIERI, RF Circuits Designer, Alenia SpA, Via Fusaro 187,
Bacoli, 80070 Naples, Italy;  (39) 81-527-2242, FAX: (39) 81-868-7552.

Knock yourself out!!

There are more transmission line (non-ferrite type) balun circuits also.

--
73, Paul, AA1LL
Greenville, NH
http://www.qsl.net/aa1ll

Sent via Deja.com http://www.deja.com/
Before you buy.

 
 
 

home made balancing transformer Qs

Post by Tom Bruhn » Tue, 12 Oct 1999 04:00:00

Andy,

I think we need some more help here from you.  Just what is this
"balancing transformer" going to balance?  What power level?  What
frequency range?  Some little things like that...  

This is an "antennas" group, and as such, usually deals with
high-frequency (above 1 megahertz) issues.  You certainly would not want
to be using a core from a mains transformer for any sort of RF
transformer.  But maybe that's not what you're about.  If it's a
lower-freqeuncy problem, perhaps a different group
(sci.electronics.design or rec.radio.amateur.homebrew) would be more
appropriate.

Cheers,
Tom


> Any tips on winding my own 3.5:1 balancing transformer?

> Can I take a miniture mains transformer, rip out all the wire and
> wind my own?

> Is 35 and 10 turns ok or do I need to go to the hassle of
> increasing that to set up a big enough magnetic field?

> Do I have to use varnished copper wire - I have a supply
> of very thin PVC coated wire, is that OK?

> Andy

 
 
 

home made balancing transformer Qs

Post by Andrew Rimel » Wed, 13 Oct 1999 04:00:00

Thanks for the information

=8-)




> > Any tips on winding my own 3.5:1 balancing transformer?

> > Can I take a miniture mains transformer, rip out all the wire and
> > wind my own?

> > Is 35 and 10 turns ok or do I need to go to the hassle of
> > increasing that to set up a big enough magnetic field?

> > Do I have to use varnished copper wire - I have a supply
> > of very thin PVC coated wire, is that OK?

> > Andy

> Hi Andy, welcome to alt.baluns.  You will get more info than you ever
> wanted by saying the magic word, "balun" on this NG!

> The performance of low frequecy 50-60Hz power supply magnetic materials
> at megahertz frequencies is not appropriate to perform efficient
> balanced-to-unbalanced transformation by flux linkage alone.  So other
> materials and circuits are used, such as building "transmission line
> transformers" with cores made of ferrite (a high frequency high mu
> material) and using windings of twisted pairs of primaries and
> secondaries.

> You can make one that will be very broadband by using a ferrite rod from
> an a.m. radio.  Obtaining impedance transformer ratios other than N^2
> where N is integer is difficult with these circuits, but a 4:1 ratio is
> easily made by the following:

>         A B
>         | |
>         | |
>      || C C
>      || C C
>      || C C
>      || C C
>      || C C
>      || C C
>         | |
>         | |
>         C D

> This poor excuse for a circuit is supposed to indicate that you make two
> windings in parallel, of number 22 wire close spaced next to each other
> or even twisted together (not critical) and fill up the whole ferrite
> rod with it.  This will be around 30 turns or so.  Connect nodes B and
> C.  For unbalanced Z ohm input (A=center conductor, B=Ground), 4Z
> balanced output is available at terminals C and D.

> Here are some references, scoffed from
> http://sites.penton.com/mwrf/index.htm  :

> TRANSFORMER TYPE BALUN REFERENCES BY Enzo Carpentieri:

> 1. C.L. Ruthroff, "Some Broadband Transformers," Proceedings of the IRE,
> August 1959, pp. 1337-1342.

> 2. L.D. Abrie, The Design of Impedance-Matching Networks for
> Radio-Frequency and Microwave Amplifiers, Artech House, 1985.

> 3. Y. Shimada, "Input-Impedance Analysis of a 1:1 Balun," IEEE
> Transactions on Microwave Theory and Techniques, May 1970.

> 4. E. Rotholz, "Transmission-Line Transformers," IEEE Transactions on
> Microwave Theory and Techniques, April 1981.

> 5. O. Pitzalis, "Practical Design Information for Broadband
> Transmission-Line Transformers," Proceedings of the IRE, 1968.

> 6. D. Myer, "Equal-Delay Networks Match Impedances Over Wide
> Bandwidths," Microwaves & RF, April 1990, pp. 179-188.

>  FOR FURTHER READING

> Grossner, Transformers for Electronic Circuits, 2nd ed., McGraw-Hill,
> 1983.

> K.B. Niclas, R.R. Pereira, and A.P. Chang, "Transmission Lines
> Accurately Model Autotransformers," Microwaves & RF, November 1992, pp.
> 67-76.

> J. Sevick, Transmission-Line Transformers, 2nd ed., American Radio Relay
> League, 1990.

> C.W. Allen and H.L. Krauss, "Wideband Rotary Transformer--Unbalanced
> Current Analysis," Proceedings of the IEEE, February 1977.

> American Radio Relay League, The ARRL Handbook for Radio Amateurs, 69th
> ed., 1992.

> ENZO CARPENTIERI, RF Circuits Designer, Alenia SpA, Via Fusaro 187,
> Bacoli, 80070 Naples, Italy;  (39) 81-527-2242, FAX: (39) 81-868-7552.

> Knock yourself out!!

> There are more transmission line (non-ferrite type) balun circuits also.

> --
> 73, Paul, AA1LL
> Greenville, NH
> http://www.qsl.net/aa1ll

> Sent via Deja.com http://www.deja.com/
> Before you buy.

 
 
 

home made balancing transformer Qs

Post by Tom Bruhn » Wed, 13 Oct 1999 04:00:00

Wonderful reply, Paul!  And I couldn't even figure out that a "balancing
transformer" was a "balun"!  Maybe we really are getting back to
non-confrontational posts.  :-)

Cheers,
Tom


> Hi Andy, welcome to alt.baluns.  You will get more info than you ever
> wanted by saying the magic word, "balun" on this NG!

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