On 25 Aug 2004 02:54:24 -0700, (Doug Goncz) wrote:

The antenna, a Radio Shack 15-2163 6-Element Triple Drive Outdoor FM
Antenna

Hi Doug,

I see nothing of twinax at all.

consult:
http://www.radioshack.com/images/Pro...OME15-2163.pdf

However, you seem to have come to a working arrangement, twinax
doesn't make all that much difference, and it is pointed in the right
direction. I'm sure you are enjoying the music.

73's
Richard Clark, KB7QHC

Dear Richard,

The Radio Shack manual linked below, which I have, and came with the
antenna, doesn't mention twiaxial cable because no twinaxial cable
with an impedance of 75 ohms is available at a reasonable price, so
people use 75 ohm cable because it's cheaper. If I could get 75 ohm
twinaxial cable I'd use it.

The impedance of this and every open dipole antenna is around 75 ohms,
one quarter of the impedance of a 300 ohm folded dipole, just about
ten percent from the impedance of empty space. We are in an
atmosphere....

However, the OEM antenna is a flexible _open_ dipole with a
characterstic impedance of 75 ohms. I think 100 ohm twinax is a good
choice.

Can any readers source 75 ohm twinax?

Doug

Richard Clark wrote in message . ..
On 25 Aug 2004 02:54:24 -0700, (Doug Goncz) wrote:

The antenna, a Radio Shack 15-2163 6-Element Triple Drive Outdoor FM
Antenna

Hi Doug,

I see nothing of twinax at all.

consult:
http://www.radioshack.com/images/Pro...OME15-2163.pdf

However, you seem to have come to a working arrangement, twinax
doesn't make all that much difference, and it is pointed in the right
direction. I'm sure you are enjoying the music.

73's
Richard Clark, KB7QHC

(Doug Goncz) wrote in message . com...
Dear Richard,

The Radio Shack manual linked below, which I have, and came with the
antenna, doesn't mention twiaxial cable because no twinaxial cable
with an impedance of 75 ohms is available at a reasonable price, so
people use 75 ohm cable because it's cheaper. If I could get 75 ohm
twinaxial cable I'd use it.

The impedance of this and every open dipole antenna is around 75 ohms,
one quarter of the impedance of a 300 ohm folded dipole, just about
ten percent from the impedance of empty space. We are in an
atmosphere....

However, the OEM antenna is a flexible _open_ dipole with a
characterstic impedance of 75 ohms. I think 100 ohm twinax is a good
choice.

Can any readers source 75 ohm twinax?

Doug

http://www.electronicsurplus.com/com...=1093701353153

I have ordered 16 feet of Belden "Blue Hose" 78 ohm twinaxial cable.

Doug

From: (Doug Goncz)

I have ordered 16 feet of Belden "Blue Hose" 78 ohm twinaxial cable.

And the impedance of an open dipole in air is about 75 ohms.

Product: 78-OHM TWINAX SOLID COAX CABLE FOIL+BRAID SHIELD 2 CONDUCTOR
20AWG 100FT/REEL NEW BLUE JACKET
Unit Price: $0.40
Quantity: 16
Items Total: $6.40


Order Subtotal: $6.40
Shipping Cost: $10.80
Tax: $0.00
Order Total: $17.20



Yours,
Doug Goncz ( ftp://users.aol.com/DGoncz/incoming )
Student member SAE for one year.
I love: Dona, Jeff, Kim, Mom, Neelix, Tasha, and Teri, alphabetically.
I drive: A double-step Thunderbolt with 657% range.

Gosh, is my face pink.

You all were right when you wrote to use a balun and 75 ohm coax, not
twinax line to run to the input of the radio. The ring connector on
the OEM dipole is a copy-protection throwoff. The true connection is
that one leg is _grounded_ to the sleeve/barrel/chassi, and the other
is connected to the tip terminal. I determined this with a sewing pin
to penetrate the dipole insulation and an ohmmeter.

But Don Foreman is instructing me in how to rewind my 300:75 ohm balun
to 75:75 ohms for the open six element triple drive antenna so my face
isn't red. That is, I am learning something.

Later, in my shop, I will install the balun core to the Wizard board
and go back to the twinax, so that the Wizard can accept a the big
antenna the way it is now, but with the plug in all the way instead of
just part way, or a new flexible open dipole that is a true balanced
dipole and doesn't have one leg grounded. It can be made from a bit of
twinax, or the existing dipole can simply be soldered to a fresh TRS
connector.

Do any of you know a software patch to get lower than 88 MHz on the
Wizard? I'd like to listen to ATC.

Doug

On 8 Sep 2004 17:36:49 -0700, (Doug Goncz) wrote:

You all were right when you wrote to use a balun and 75 ohm coax, not
twinax line to run to the input of the radio.

Hi Doug,

This probably won't make much difference, because it is hardly an
application killer.

Do any of you know a software patch to get lower than 88 MHz on the
Wizard? I'd like to listen to ATC.

Lower than 88MHz? To what? 550KHz AM?

73's
Richard Clark, KB7QHC

Richard Clark wrote in message . ..
Lower than 88MHz? To what? 550KHz AM?

73's
Richard Clark, KB7QHC


Oops. Lower than 88 MHz are TV channels. I forgot that ATC is higher
than 108 MHz. Looked it up in Pocket Ref by Glover.

Doug