[Antennas] balun question
John Tait
[email protected]
2002年4月15日 09:37:58 +0100
Hi John...
Subject: [Antennas] balun question
> I have a Van Gordon 4:1 balun that I use on my
> homebrew G5RV antenna. It goes between the 300 ohm
> twinlead and the 75 ohm coax. While doing some
> checking on my different coax runs this weekend,
> noticed that the coax for the G5RV is shorted between
> the center pin and the braid. Traced the short back
> to the balun. Is this normal for a 4:1 balun-to have
> the center pin and outside connector shorted, or did
> mine go bad. Any feedback is appreciated.
It is normal to get continuity across the 4:1 balun... It is NOT normal
to get continuity across the coax on its own.. It is also not normal to use
a 4:1 balun on a G5RV.. The whole point of the G5RV design, is that it has
a low impedance at the junction of the coax and 300 Ohm twinlead. If you use
the 4:1 balun, you may as well dispense with the ribbon, and put the balun
at the centre of the antenna instead. A 1:1 current balun however, probably
would be beneficial at the junction of the coax and 300 Ohm twinlead.
73
John EI7BA