= = = starman wrote in message
= = = ...
Michael Lawson wrote:
"starman" wrote in message
The size (gauge) of the wire is not important for a *reception*
antenna.
It does matter for a transmitting antenna. The typical inverted-L
has an
impedance of several hundred ohms for much of it's frequency range.
That's why a 9:1 (impedance) balun is often used. If the receiver
has an
antenna input impedance of about 50-ohms, a 9:1 balun will match it
to a
450-ohm antenna (9x50=450). The wire turns ratio for a 9:1 balun is
actually 3:1. My balun has a primary winding with 10-turns and a
secondary with 30-turns. I used #22 enameled wire on a 1/2" dia.
type-43
ferrite core. I plan to make a new balun using a 'binocular' core.
This
core shape makes the balun's impedance more consistent throughout
it's
frequency range.
Is there much of a difference in the gauge of the enameled
wire wound around the core?? I followed John Bryant's
lead in his article and used 30 gauge wire, but I was thinking
that 26 would be easier to handle.
--Mike L.
Use whatever size wire works best on the ferrite core you have.
STARMAN,
Isn't Type 43 the recommended as a Balun "Core Material" ?
Why isn't Type 61 also a 'suggested' Balun Core Material ?
NOTE: Matching Transformer = Balun = UnUn
True Story: A while back I bought a Grab Bag of Feritte Cores on eBay.
Some of them had a #20 Enameled Wire wrapped on them with 36 Turns.
They were about 1" OD x 1/2" ID x 1/2" H. So I thought, why not
try them as an Matching Transformer on an 'old' Telephone Two Wire
Service Line (pre-1950s) that runs overhead about 75 Ft from
the Power Pole to the House. Being lazy I simply wrapped a Twelve
Turn (12T) Secondary and wired it up with a #22 Magnet Wire from a
RadioShack 'three pack' Catalog # 278-1345 ($5). Well 36:12 Turns
worked good for AM/MW and up to 7 MHz but the Signal Levels fell
off after 7 MHz. So then I tried Reducing the Primary to 30
Turns and the Secondary to 10 Turns. Again the AM/MW Band was
good and the Shortwave coverage went up to 23 MHz. Not being
one to settle for 'good enough'; I then tried Reducing the Primary
to 24 Turns and the Secondary to 8 Turns. Well the AM/MW Reception
went down and the Shortwave Bands reception picked up to the CB Band.
So it seems that the 'majic' 30 Turns and 10 Turns worked the best
for my needs using this ?Core?.
TESTING: The receiver for this Test was an Icom IC-R75.
http://www.icomamerica.com/products/receivers/r75/
My Matching Transformer "Test Standard" was an ICE 180A.
http://www.arraysolutions.com/Produc...age%20Matching
My Test Measurement were with "My Ears" and 'My Eyes' (S-Meter).
The 'old' Telephone Service Line was a Two Wire (Copper Clad
Steel?) Cable. One Wire was used for the ICE 180A and the
other Wire was used for the ?Core? Matching Transformer.
FWIW: Reading your statement about the Binocular Cores, I
have just ordered some from Universal-Radio.Com to Test.
It is my understanding that One Turn 'counts' for Two when
You use a Binocular Core. Now Is That True ?
Also, I have a SWL 10:1 Balun that is made by "RF Junkie"
and will be testing it soon using the same test-set-up.
* Two Shortwave Listener (SWL) 10:1 Baluns for Random Wire Antennas
http://groups.yahoo.com/group/Shortw...a/message/1523
iane ~ RHF
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