93 ohm coax
 

I have been given 300mtrs of 93 ohm coax.Can this be used in pair to give 46
ohms? Thankyou, David ZL2DG

Yes.

If you are going to use it at VHF, match the lengths electrically. At HF mechanical length is good enough. And, you do
understand that they are to be connected in parallel, both centers tied together and both shields, right?

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Crazy George
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"David McBeth" wrote in message ...
I have been given 300mtrs of 93 ohm coax.Can this be used in pair to give 46
ohms? Thankyou, David ZL2DG

"Crazy George" wrote in message
...
Yes.

If you are going to use it at VHF, match the lengths electrically. At HF
mechanical length is good enough. And, you do
understand that they are to be connected in parallel, both centers tied
together and both shields, right?

Right you are -
If hooked up the other way it would effectively be 186-ohm shielded balanced
cable.

On Sun, 30 Jan 2005 02:36:18 -0500, "Hal Rosser"
wrote:
Right you are -
If hooked up the other way it would effectively be 186-ohm shielded balanced cable.
And if you hooked it up both ways, it would be a 4:1 BalUn. -kinda-

73's
Richard Clark, KB7QHC

David McBeth wrote:
I have been given 300mtrs of 93 ohm coax.Can this be used in pair to give 46
ohms? Thankyou, David ZL2DG

Not only will paralleling result in Z0=46 ohms but series'ing
them will result in Z0=186 ohms which will, for non-resonant
antennas, lower the I^2*R losses.
--
73, Cecil http://www.qsl.net/w5dxp


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Ian Jackson wrote:

Cecil Moore writes:
Not only will paralleling result in Z0=46 ohms but series'ing
them will result in Z0=186 ohms which will, for non-resonant
antennas, lower the I^2*R losses.

OK. I have just realised what you mean. Use two cables as 186 ohm
screened twin.
Sorrrry!

What I said was confusing. Sorry about that. What I meant was
that using twin runs of 93 ohm coax as parallel transmission
lines would result in lower losses than using a single run of
similar 50 ohm coax for non-resonant antennas. That was just an
observation, not an approach that I would recommend. Sorry
for the confusion.
--
73, Cecil http://www.qsl.net/w5dxp


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On Sat, 29 Jan 2005 23:48:13 -0800, Richard Clark wrote:
On Sun, 30 Jan 2005 02:36:18 -0500, "Hal Rosser"
wrote:
Right you are -
If hooked up the other way it would effectively be 186-ohm
shielded balanced cable.

And if you hooked it up both ways, it would be a 4:1 BalUn. -kinda-

And, if you solder _everything_ together, they make great radials.

Long story (sort of) short: Back in the early 90's when the U.S.
building and/or fire codes outlawed the material then used as the
outer jackets on RG-62 and the such, a large bank where I was
consulting had to rip out a gazillion furlongs of it from up in
the ceilings of the building. (Probably A Real Good Thing -- if
for no other reason than they always put in "new stuff" for each
new generation of terminal/monitor/display that came along. The
ceilings were overdue for a complete colapse...)

I hauled off as much as I could load into my trunk each day.

By fabricating 1/4 wave lengths of the stuff paralleled in sets of
2, 3, and 4, I built matching sections for various Field Day verticals.
I used the "worst" of it for radials on a 2-element, phased 40M
vertical -- and used 2-pair paralled runs for the phasing section(s)
between the 2 elements.

Used a grid dip meter and receiver to cut the stuff to length.

73
Jonesy
--
| Marvin L Jones | jonz | W3DHJ | linux
| Gunnison, Colorado | @ | Jonesy | OS/2 __
| 7,703' -- 2,345m | config.com | DM68mn SK

"David McBeth" wrote in message
...
I have been given 300mtrs of 93 ohm coax.Can this be used in pair to give
46
ohms? Thankyou, David ZL2DG

Yep, just like paralleling resistors. I used to run two parallel RG-59 feed
lines to my 1/4-wave verticals. It matched the vertical impendence very
nicely, and the amplifier's PI network tuning could handle 36-ohm load OK.

ak