Question for ya folks.

I took down my co-ax that was feeding my inverted Vee antenna. I replaced it
with 450 ohm ladder line and then at the window I put the 4-1 balun that was
at the feed point and ran co-ax into the house.
Question is.... Is there a better way to feed this sucker..I was thinking
about a co-ax cable balun 1:1 , but might handle the mismatches easier. I
don't care about the SWR on the ladder line since losses so low and it will
all be radiated anyway eventually.
Just don't want the 4:1 to fail one day.

Would love to hear thoughts on this.
Thanks.

VE7REF- Andrew

In message XAS0i.1159$V75.117@edtnps89, Andrew
writes
Question for ya folks.

I took down my co-ax that was feeding my inverted Vee antenna. I replaced it
with 450 ohm ladder line and then at the window I put the 4-1 balun that was
at the feed point and ran co-ax into the house.
Question is.... Is there a better way to feed this sucker..I was thinking
about a co-ax cable balun 1:1 , but might handle the mismatches easier. I
don't care about the SWR on the ladder line since losses so low and it will
all be radiated anyway eventually.
Just don't want the 4:1 to fail one day.

Would love to hear thoughts on this.
Thanks.

VE7REF- Andrew



I'm sure that others will come up with some informative suggestions.
However, while I'm not saying that a 4:1 balun is not appropriate in
this case, I always wonder why one is included almost 'for good luck' in
many HF installations. Surely you would only use one to carry out an
accurate 4:1 transformation between two known impedances? I understand
that baluns with ferrite cores are not too happy when working far
outside the correct impedance ratio.
Ian.
--

Andrew,

There is a good discussion on this at:

www.dxengineering.com/Products.asp?ID={022A1CDF-C417-4F8B-AF97-B1ED91AAE23A}&SecID=10&DeptID=33

You may need to cut and past that to get it to work. DX Engineering
is pricey, but they do know their stuff.


--
Alan
WA4SCA

"Andrew" wrote in message
news:XAS0i.1159$V75.117@edtnps89...
Question for ya folks.

I took down my co-ax that was feeding my inverted Vee antenna. I replaced
it with 450 ohm ladder line and then at the window I put the 4-1 balun
that was at the feed point and ran co-ax into the house.
Question is.... Is there a better way to feed this sucker..I was thinking
about a co-ax cable balun 1:1 , but might handle the mismatches easier. I
don't care about the SWR on the ladder line since losses so low and it
will all be radiated anyway eventually.
Just don't want the 4:1 to fail one day.

Would love to hear thoughts on this.
Thanks.

VE7REF- Andrew

Hello Andrew -

I am assuming that is an inverted Vee dipole.
What frequency?
How high up is the center.

The optimum feedline impedance for your antenna depends on frequency and
effective height above the ground.
If your antenna is for 40m or 80m, I would figure that your feedpoint
impedance would be 50 ohms or lower
(450 ohms divided by 4 is still way off); that's unless you have some very
tall trees or your inverted vee is for one of the higher frequency bands.

So, RG58 or 8x cable would be good for reasonable impedance match.

My experience has been that if the feedline can be fairly perpendicular to
the antenna wires at the feedpoint, the balun is not needed. One thing a
balun does is help prevent the coax shield from becoming part of the
radiator. An indication of that is if the antenna resonates lower than it
should for the calculated antenna wire length, then a balun might be useful.
Baluns add loss, may be affected by weather, and can cause TVI. (My W2AU
balun was bad news for TV's when I operated on 10 meters with their 1:1
balun.)

For ground mounted verticals (impedance around 30 ohms), I run parallel
RG58 or parallel RG59 feedline to my feedline tuner. For dipoles less than
1/4 wave up, RG58 or 8x usually matches things up.
For dipoles higher up that 1/4 wave, RG-6 (cable TV coax) and RG=59 works
well.

Coax isn't affected by being on or under the ground, being draped through
tree limbs, or by being taped to metal poles or tower sections. Parallel
feedlines don't like those sorts of things. So I suggest - just keep it
simple. Match the coax impedance to the wavelength height of your antenna
and skip the balun.

73,
Andy K4YKZ