In message , Ralph
Mowery writes
"R. Scott" wrote in message
...
On 1/28/2014 1:25 AM, wrote:
The vehicle is a 2011 F-350 and I have the Fender Mount CB. Like I said I
use it only for the RV runs. Thus I would like to experiment with one of
the whips to run a 2 meter. I could have easily did a 1/4 wave vertical
but thought that 5/8 would be better experiment.
the loaded 5/8 ungrounded as NM5K posted just might be what I need. I was
looking for how many turns of wire might do the trick. Problem is I dont
have a GDO to get the right turns so thats why I was hoping to find
someone whom ad done it before 
.
I saw an antenna similar to what you are wanting to do. I think it was 47
inches long. The coil will only be a few turns. I don't recall the number
of turns on the form for that antenna, but it was only about 2 or 3 turns.
I would start with 3 turns and check the swr and trim the turns for a low
swr.
Most 5/8ths on 2m are more-or-less electrically 6/8th (=3/4) waves, but
with the first 1/8th being the coil. With mine, the whip is 50" long,
and the coil is 3.5 turns, 1" dia, appx 10 gauge well spread steel
spring, 1.75" long. The feed impedance over a flat groundplane (7"
magmount in the centre of the car roof) should be around 50 ohms,
whereas a 1/4 is more like 37 ohms. In most situations, I've not found
it remarkably better the a 1/4 wave (maybe a couple of dB on a good
day).
--
Ian