More j poll questions
 

Is there a way to tune a j pole besides moving the coax up or down?

On 6 Jan 2005 13:47:57 -0800, wrote:
Is there a way to tune a j pole besides moving the coax up or down?

Well, errr, Bub, you ain't "tuning" a J-Pole by "...moving the coax up or down".

You 'tune' a J-Pole by whacking off, or whacking on 'calculated' lengths
of the 2 parallel pieces.

There be a difference between "tuning" and "Matching".

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

Allodoxaphibia wrote:
On 6 Jan 2005 13:47:57 -0800, wrote:
Is there a way to tune a j pole besides moving the coax up or down?

Well, errr, Bub, you ain't "tuning" a J-Pole by "...moving the coax
up or down".

You 'tune' a J-Pole by whacking off, or whacking on 'calculated'
lengths
of the 2 parallel pieces.

There be a difference between "tuning" and "Matching".

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

Ok, I understand what you are saying. Moving the coax affects the
"impedance". How does one effectively "tune" then by shortenign or
lengthening the elements?

Moving the coax up or down only changes the impedance.
there is a sweet spot of 52 ohms between the lower end 700 ohms and
the upper end 300 ohms of the impedance range.

Tuning for a center frequency is most easily accomplished by
installing a brass machine screw in the pipe caps after you shorten
the antenna and stub slightly to give you tuning room.

TTUL
Gary