> There is no short from center to ground. I get contact from the center
> pin of the PL-259 to the tip of the antenna.
Are you saying there is no DC connection between the center pin of the
coax connector and *ground*? The "ring" (a single turn coil) should
have connections to both the vertical (whip) and the ground (shell of
the UHF connector). If there is no connection from the shell of the
coax (via the bracket) to the bottom of the coil, the antenna will not
be tuned properly since the coil actually *resonates* the antenna.
The basic Ringo (AR-2) is slightly longer than 5/8 wave - the single
turn coil resonates the antenna and the tap is adjusted for a 50 Ohm
match. The ARX-2 stacks a 1/2 wave vertical on top of the 5/8 wave
antenna and the "stub" between the two provides a 180 degree phase
shift so the two elements radiate in phase for added gain.
Again, if the coil is not connected at the bottom, the antenna will
*never* resonate ... more likely it will be "resonant" somewhere
around 54.5 MHz *as a 1/4 wave vertical* or 160 MHz as a 3/4 wave
vertical depending on the behavior of the feedline shield.
Couple a grid dip meter to the ring and see if/where you get a dip.
73,
... Joe, W4TV
On 3/11/2013 6:59 PM, Kipton Moravec wrote:
I am testing the antenna on the ground held on a fiberglass pole about 8
feet long, so the base is about 8 feet off of the ground and I am
holding it up and standing under it.
We have a 15 foot piece of RG8X attached to it. There are no other
things in the path.
That goes directly to an antenna analyzer that makes a graph of SWR. For
+/- 50 MHZ centered at 146 MHz we get a straight line 10:1 SWR.
We moved the tap a couple of times with no changes.
It seems like there are no glued parts that could be assembled wrong.
There is no short from center to ground. I get contact from the center
pin of the PL-259 to the tip of the antenna.
I have completely disassembled the antenna, and am using emery cloth on
all the places metal meets metal. I am wondering what else I should do
before I reassemble since I got it apart.
Kip
On Sun, 2013-03-10 at 20:34 -0400, w4lde wrote:
Kip,
Where are you reading the SWR from? at the antenna or back in the
shack? Three is no LP, HP filters, lighting protection devices in feed
line is there? If so did you eliminate them?.
What happens after you move the tap point on the ring, SWR change?
Anymore info on how you are testing the SWR would help us.
73 de
Ron W4LDE
On 3/10/2013 8:19 PM, Kipton Moravec wrote:
I was given a used Ringo ARX2B antenna.
I checked out the manual and set the three measurements to 145 MHz. When
I tried to tune it, the SWR was 10:1 +/- 50 MHz around 146 Mhz.
The piece of coax looked weathered and I checked it out and it was fine
with the Ohm Meter and did not seem to change SWR or Ohms when I flexed
it. But I replaced it anyway.
Found their was no contact through the hair pin to the upper section
from the Ohm meter. So I replaced the screws and got a good connection
according to Ohm Meter.
I checked the connections from the end of the coax to all the points on
the antenna, and it worked as expected with the Ohm Meter. No unexpected
opens or shorts.
When I tried the analyzer, I still had a 10:1 SWR for +/- 50 MHz around
146 MHz.
So now I have disassembled everything and an using emery cloth on all
the connections and replacing all steel nuts and bolts with stainless,
and replacing the brass nuts.
What else should I look at before I reassemble?
I really do not understand how I could have such a bad SWR unless I had
an open or a short -- which I proved I did not have before I
disassembled. I am not sure what else to look for.
The manual is here:
http://www.radiomanual.info/schemi/ACC_antenna/Cushcraft_ARX2B_user.pdf
Kip
AE5IB
_______________________________________________
_______________________________________________
TowerTalk mailing list
TowerTalk@contesting.com
http://lists.contesting.com/mailman/listinfo/towertalk
_______________________________________________
_______________________________________________
TowerTalk mailing list
TowerTalk@contesting.com
http://lists.contesting.com/mailman/listinfo/towertalk
_______________________________________________
_______________________________________________
TowerTalk mailing list
TowerTalk@contesting.com
http://lists.contesting.com/mailman/listinfo/towertalk
_______________________________________________
_______________________________________________
TowerTalk mailing list
TowerTalk@contesting.com
http://lists.contesting.com/mailman/listinfo/towertalk
|