Well written Ron!
On Tuesday 13 November 2007 19:48, Ron D'Eau Claire wrote:
> Consider a center fed wire. At the frequency where the wire is at 1/2
> wavelength long the impedance at the center is usually about 50 ohms (in
> free space it would be 75 ohms, but as one moves close to the earth, the
In a message dated 11/13/07 3:19:30 PM Eastern Standard Time,
[EMAIL PROTECTED] writes:
> Almost universally, there seems to be
> no recognition that even though the feedline is matched at the radio,
> it is indeed NOT matched beyond the tuner. The feedline can see
> humongous mismatch (hi
There's another issue that leads to greater feed line efficiency in addition
to the points Jack made: keeping the SWR relatively low. That is, less than,
say, 15:1 or less. All feed lines become lossy at high SWRs. One reason, as
Jack mentioned, is the likelihood of dielectric breakdown. That's usu
This whole discussion amazes me. Almost universally, there seems to be
no recognition that even though the feedline is matched at the radio,
it is indeed NOT matched beyond the tuner. The feedline can see
humongous mismatch (high SWR) and the operator doesn't know because
the tuner hides it
If you haveever tried to remove housepaint from a coax, black or whatever,
you'll know that best way to match the coax to the house is to paint it with
your color of choice. I have a 45 year old Moseley vertical ant that I paint
with latex exterior paint and it lasts until you take it off. Plea
Don and All,
I agree that many of the RG-59 and RG-6 coax available will work just
fine. In two cases I found RG-59 CATV-type coax purchased at a big box
store that showed real signs of heat-stress after a few months of
operation at 100+ watts.
My observation is that quality and suitability
You can slip the black coax inside a white tube such as white plastic
tubing at Home Depot for water lines. Or use white RG6. It is low loss and
even though 75 ohm it will work quite well. I use it for 80 and 160M with
1500W. I don't think it will last as long outside as coax made to be UV
resista
Doug,
I beg to differ. There are physical properties that give rise to the
characteristic impedance which are related to the dielectric properties
and the relative conductor diameters for the center conductor and the
braid. These same properties will create a particular RF voltage
handling
There are many types of cable designated RG-6 and RG-59. Many are not
designed to handle rf voltages typical of ham transmissions. My
suggestion is to be *careful* what you select. Good quality RG-59, the
type broadly used by hams many years ago, is hard to find right now.
We're not talking
HUH???
So cable companies are not transmitting down those lines?
RG-6 cable can handle about 800 watts at 50mhz.
On 11/12/07 6:00 PM, "Doug Person" <[EMAIL PROTECTED]> wrote:
> I would be very careful about only using coax that is rated for RF
> transmission. TV/CATV type RG-6 and RG-59 are d
On Mon, 12 Nov 2007 20:08:11 -0500, Don Wilhelm wrote:
>This is a little known fact - 75 ohm coax has less loss than
>comparable 50 ohm coax, and even with a 1.5 SWR, the increased
>loss will not be sufficient to bring the total loss to that of
>the 50 ohm coax. Besides, the 75 ohm coax is usually
Art,
I would use the RG6 coax which is commonly available at Home Depot and
Lowes. If you want to use PL-259 connectors, the adapters for RG59/RG8X
will normally fit.
Even though it is 75 ohm, and in a 50 ohm system will operate with an
SWR of 1.5 - if you look at the loss figures carefully
I would be very careful about only using coax that is rated for RF
transmission. TV/CATV type RG-6 and RG-59 are designed for VHF/UHF
reception only.
Doug -- K0DXV
Kenneth E. Harker wrote:
On Mon, Nov 12, 2007 at 03:50:14PM -0800, Art Horne wrote:
Greetings,
Can anyone recommend a W
Art,
The reason most coax outer jackets are black is to slow breakdown of the
plastic material by UV rays. There is not much coax designed for
outdoor use that is not either black or possessed of a solid metal outer
conductor. You could try getting your hands on some coax hardline of
the cab
There is also RG-213 in clear jacket, with silver braid. It is usually
very low loss and often used for low-GHz applications.
Leigh/WA5ZNU
Art K6KFH:
Greetings,
Can anyone recommend a WHITE coax for antenna lead of about 40-50' ?
My XYL
is very fussy about wires showing and black sticks o
On Mon, Nov 12, 2007 at 03:50:14PM -0800, Art Horne wrote:
> Greetings,
>
>
>
> Can anyone recommend a WHITE coax for antenna lead of about 40-50? ? My XYL
> is very fussy about wires showing and black sticks out like a sore thumb.
> Would the coax used by TV cable installers work ok? I?m onl
You can find white rg-6 at home depot. This is 75 ohm coax.
I would think someone might carry white 58 or 8x if you call around.
On 11/12/07 5:06 PM, "Tom Hammond" <[EMAIL PROTECTED]> wrote:
> Art:
>
> Most (maybe some) marine radio shops regularly use white RG-58 and
> RG-8X sized coaxes.
>
Art:
Most (maybe some) marine radio shops regularly use white RG-58 and
RG-8X sized coaxes.
73,
Tom N0SS
At 17:50 11/12/2007, you wrote:
Greetings,
Can anyone recommend a WHITE coax for antenna lead of about 40-50' ? My XYL
is very fussy about wires showing and black sticks out like a
18 matches
Mail list logo
