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Old March 15th 05, 03:05 AM
john doe
 
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No I didn't account for the PVC ...... but I made it longer than my design
and then trimmed past my design length and it never seemed to make a
difference. Considering my inductor was also formed around the PVC that was
probably way off too.....

I modeled the whole thing with nec first. This is what my input file looked
like:
http://mywebpages.comcast.net/ka2pbt/2M-5-8wave-dat.txt

and this is what my output looked like:
http://mywebpages.comcast.net/ka2pbt/2M-5-8wave-out.txt

Construction was a radiator 58.5 inches long fed along a 1/2" sched-40,
inductor was 19 turns around the same sched-40 2 inches long. The were 4
radials at 90 deg each 19.38"

Any comments welcome ....

Thanks,

-- de ka2pbt

"Dave Platt" wrote in message
...
Can anyone point me to a good site for construction a 5/8 wave 2M
antenna???

I tried home-brewing one already with poor results .... a conductor up a
piece of PVC .... same conductor wound into a coil at the bottome
connected in series to the center of the coax. 4 1/4 wave radials
connected to outer conductor.


I believe there's a project in the ARRL Handbook which shows how to
convert a Radio Shack CB whip antenna to a 2-meter 5/8-wave - it has
the details for the matching coil that is required.

http://www.arrl.org/tis/info/pdf/8009022.pdf has another QST article
which shows how to construct one from scratch, using a technique that
doesn't require a matching coil (the matching inductor is made from a
stub).

I haven't tried either of these myself.

With regard to the version you made - did you account for the loading
effect of the PVC when you measured and trimmed the length of your
radiator?

--
Dave Platt AE6EO
Hosting the Jade Warrior home page: http://www.radagast.org/jade-warrior
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