K40 high SWR
 

Picked up a brand new K-40 and found it to tall for the trunk lip so I
mounted it on the rear bumper.
Now I cant get the SWR below 3:1, all ground connections are good.

HOWEVER For neat installation I did cut the coax to about 4 feet, being a
base loaded I assumed that was OK ?
Does anyone know if that matters with K-40's
I will read comments in the group.

-RP

On Tue, 26 Aug 2003 03:44:00 GMT, "RP Jones"
wrote:

Picked up a brand new K-40 and found it to tall for the trunk lip so I
mounted it on the rear bumper.
Now I cant get the SWR below 3:1, all ground connections are good.

HOWEVER For neat installation I did cut the coax to about 4 feet, being a
base loaded I assumed that was OK ?
Does anyone know if that matters with K-40's
I will read comments in the group.

-RP

Don't know about the specifics of the K-40 but here's a quote from a
similar antenna.

1976 Antenna Specialist Co. concerning 17 foot cable length on base
loaded magnet mount.

" The cable length, as supplied, is a part of the electrical circuit
of the antenna. Altering its length by cutting may produce undesirable
VSWR effects. Cable length should not be changed."

Hello Tnom:

Good call. The cable length will be more critical if the antenna is a
magnetic mounted antenna, as the coax is now part of the counter poise.
Thats why a good ground connection to the antenna end of the coax is
important. And that ground connection is connected to metal body of the
vehicle.

Antennas are like light bulbs, they need two wires to. So manufactures
in there design will rely on the coax as being the other part of the
antenna. In mobile installations sometimes there isn't a choice.

Jay in the Mojave

wrote:
On Tue, 26 Aug 2003 03:44:00 GMT, "RP Jones"
wrote:


Picked up a brand new K-40 and found it to tall for the trunk lip so I
mounted it on the rear bumper.
Now I cant get the SWR below 3:1, all ground connections are good.

HOWEVER For neat installation I did cut the coax to about 4 feet, being a
base loaded I assumed that was OK ?
Does anyone know if that matters with K-40's
I will read comments in the group.

-RP


Don't know about the specifics of the K-40 but here's a quote from a
similar antenna.

1976 Antenna Specialist Co. concerning 17 foot cable length on base
loaded magnet mount.

" The cable length, as supplied, is a part of the electrical circuit
of the antenna. Altering its length by cutting may produce undesirable
VSWR effects. Cable length should not be changed."

"RP Jones" wrote in
message
...
Picked up a brand new K-40 and found it to tall
for the trunk lip so I
mounted it on the rear bumper.
Now I cant get the SWR below 3:1, all ground
connections are good.

That may be the reason right there. On the bumper
the radiating section of the antenna is in close
proximity to the body of the vehicle.

The other possibility is to check and make sure
that the metal section of the bumper the antenna
is mounted on is really electrically connected to
the body of the vehicle. With all of the plastic
used on cars now you can't take anything for
granted.


--
Leland C. Scott
KC8LDO

Saw this on a Tee-shirt:

"I am a
bomb
technician
if you see me
running
try to keep up "