and I bet the antenna was matched better to the radio with that stub
connected?
I get that it helped to reduce static build up or something, but how does a
quarter wave stub do that?
73
Colin, V A6BKX
----- Original Message -----
From: "Butch Bussen" <[log in to unmask]>
To: <[log in to unmask]>
Sent: Thursday, April 07, 2011 5:22 PM
Subject: Re: antenna lengths
> The 468 comes in to play as dipoles have what is called an end effect of
> around 5 percent.
> I'm not sure where the formula for the loop comes from but if you're
> figuring say a quarter or half wave stub, you use 300 meters which is a
> full wave length and the speed of light. To convert this, take meters
> times 3.28 so 984 over frequency gives youa full wave length. for a
> quarter wave stub, for example, divide this by 4 and then that number
> times the volocity factor of your coax.
>
> Way back when I was selling a lot of cb rigs, and people were running
> quarter wave whips, 102 inches long. These ghings would pick up enough
> static here in a dirt storm, you could lay the pl259 on the dash and
> sparks would jump from the center pin to ground. Needless to say, this
> was hard on fet transister front ends, so her was my fix. I would divide
> 984 by 27 mhz, which comes out 36.444 and 36.44 divided by 4 for a quarter
> wave in feet is 9.111. The coax I used which was rg58 had a volocity
> factor of around .7 as I recall, so 9.111 times .7 is 6.377 feet. I'd
> make this stub, short one end and put it on a t connector on the radio
> with the antenna to the other leg. It was a dc short, but as a quarter
> wave looks open at its frequency, the radio didn't know it was there.
> Worked like a champ!!
>
> 73
> Butch
> WA0VJR
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