With respects to antenna matching, i.e.: 50 to 450 Ohms, which is better to use, an autotransformer or a transformer with an isolated primary and secondary? I'm looking for the pro's and con's of each.


--
Yours truly,
Chuck

WA3IAC
FN20la

http://www.qsl.net/wa3iac/

Chuck S. wrote:
With respects to antenna matching, i.e.: 50 to 450 Ohms, which is better to use, an autotransformer or a transformer with an isolated primary and secondary? I'm looking for the pro's and con's of each.


--
Yours truly,
Chuck

WA3IAC
FN20la

http://www.qsl.net/wa3iac/

Hi Chuck, If I read your question correctly, you want to match a 450
ohm antenna, with no reactive component, to a 50 ohm transmission line.
In this case a 9:1 transformer would do the trick.
If however you are trying to match an antenna fed with a length of
450 ohm line down to the transmitter, where it will need to be
transformed to 50 ohms, an "L" network or some other impedance matching
network will be required. The impedance seen at the end of the 450 ohm
line, in this instance, will rarely be 450 ohms resistive.
Gary N4AST

Ok Gary, I would like to match a 50 Ohm radio to a 450 Ohm antenna input. I
know an "L" network would work, but what I was looking for is if an auto
transformer would be as good or use a transformer with a isolated primary
winding.


wrote in message
ups.com...
Chuck S. wrote:
With respects to antenna matching, i.e.: 50 to 450 Ohms, which is better
to use, an autotransformer or a transformer with an isolated primary and
secondary? I'm looking for the pro's and con's of each.


--
Yours truly,
Chuck

WA3IAC
FN20la

http://www.qsl.net/wa3iac/

Hi Chuck, If I read your question correctly, you want to match a 450
ohm antenna, with no reactive component, to a 50 ohm transmission line.
In this case a 9:1 transformer would do the trick.
If however you are trying to match an antenna fed with a length of
450 ohm line down to the transmitter, where it will need to be
transformed to 50 ohms, an "L" network or some other impedance matching
network will be required. The impedance seen at the end of the 450 ohm
line, in this instance, will rarely be 450 ohms resistive.
Gary N4AST

wrote:

Chuck S. wrote:
With respects to antenna matching, i.e.: 50 to 450 Ohms, which is better to use, an autotransformer or a transformer with an isolated primary and secondary? I'm looking for the pro's and con's of each.


--
Yours truly,
Chuck

WA3IAC
FN20la

http://www.qsl.net/wa3iac/

Hi Chuck, If I read your question correctly, you want to match a 450
ohm antenna, with no reactive component, to a 50 ohm transmission line.
In this case a 9:1 transformer would do the trick.
If however you are trying to match an antenna fed with a length of
450 ohm line down to the transmitter, where it will need to be
transformed to 50 ohms, an "L" network or some other impedance matching
network will be required. The impedance seen at the end of the 450 ohm
line, in this instance, will rarely be 450 ohms resistive.
Gary N4AST

An autotransformer configuration would allow the buildup of
static electrical charges to go to ground.

Irv VE6BP
--
--------------------------------------
Diagnosed Type II Diabetes March 5 2001
Beating it with diet and exercise!
297/215/210 (to be revised lower)
58"/43"(!)/44" (already lower too!)
--------------------------------------
Visit my HomePage at http://members.shaw.ca/finkirv/index.html
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--------------------
Irv Finkleman,
Grampa/Ex-Navy/Old Fart/Ham Radio VE6BP
Calgary, Alberta, Canada

Chuck S. wrote:
With respects to antenna matching, i.e.: 50 to 450 Ohms, which is better
to use, an autotransformer or a transformer with an isolated primary and
secondary? I’m looking for the pro’s and con’s of each.

Where are you going to find a 450 ohm antenna?
--
73, Cecil http://www.qsl.net/w5dxp

"Chuck S." wrote in message
news:KIGpf.10022$aU4.4108@trnddc06...
With respects to antenna matching, i.e.: 50 to 450 Ohms, which is
better to use, an autotransformer or a transformer with an isolated
primary and secondary? I'm looking for the pro's and con's of each.
==========================================

It all depends on what you want the transformer to do besides perform
an impedance matching function.

Otherwise there's little to choose between them. The autotransformer
will have slightly less loss.

More details please.
----
Reg.

Someone ask for more info. Well Cecil I was thinking of matching to a
Beverage antenna. From what I read they are around 450 Ohms, maybe more or
less some. Most seem to use a transformer with an isolate primary, but in
the ARRL antenna book, 2005, CH. 13 they show a auto transformer. I was
interested in hearing from someone if one type is better then the other. I
have built both types and tested them on the bench with a resistor load and
they seem to work the same. I don't have the room to put up a Beverage
antenna otherwise I would.

Chuck
"Cecil Moore" wrote in message
news
Chuck S. wrote:
With respects to antenna matching, i.e.: 50 to 450 Ohms, which is better
to use, an autotransformer or a transformer with an isolated primary and
secondary? I’m looking for the pro’s and con’s of each.

Where are you going to find a 450 ohm antenna?
--
73, Cecil http://www.qsl.net/w5dxp