On Nov 10, 5:57*pm, Tom Horne wrote:
On Nov 9, 5:51*pm, Dave wrote:





On Nov 9, 2:28*am, Tom Horne wrote:

On Nov 5, 7:26*pm, Dave wrote:

On Nov 4, 3:16*am, Peter Taggart wrote:

Greetings:

Building a 4 square *antenna system: * *How should I tune each
element? should I *place a 50 ohm load on three *elements * *then tune
up *one using my MFJ 259 *after that element is tuned place the 50 ohm
load on it then tune up the next *element repeat till all have been
tuned?

OR should I short the other three *elements to the counterpoise * tune
the element them repeat till all have been tuned?

Or should * the three be left floating * *then tune the one then
repeat till all have been tuned?

If you are using one of the commercial hybrid phasing networks or one
designed from the 4u1un book proceedure then the normal method is
this:
1. erect ONLY one vertical with its intended ground system.
2. feed it with 50 ohm line and adjust length for resonance at the
center frequency you want
3. replace 50 ohm line with 1/4 wave 75 ohm foam coax (must be foam or
1/4 wave won't reach corners of standard 1/4 wave spaced elements)
4. build other 3 elements identical to the first one.

Dave
Please forgive my ignorance but for the sake of my education would you
flesh out number three some more. *We used a four square for the 2008
field day and I watched the construction process very carefully but I
don't recall what kind of seventy five ohm coax we used. *Does using
foam coax bring the velocity factor closer to one so that the cable is
thus longer. *I don't remember having any problem with the cable
lengths but I freely admit I was functioning as labor rather than
design or supervision. *So maybe that had all been worked up in
advance so those of us assembling the antenna didn't have to cope with
it. *I might well be putting my lack of education on display by asking
this but it is the only way I will learn. *Could you not use the right
multiple of quarter waves and thus get the length you need with any
seventy five ohm cable? *I realize we would have increased the
transmission line losses but would it be enough to be significant on
say forty meters. *That's what our four square was built for. *When we
were testing it weeks ahead of time it appeared to perform very well.
We got at least two S units better signal reports when compared with a
single vertical.
--
Tom Horne, W3TDH
--
Tom Horne, W3TDH- Hide quoted text -

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the cable i normally use is rg-11u with foam dielectric, that gets the
velocity factor up to .78-.80 so the cable is longer to get the
required 1/4 wave. *since the distance from the center to the corner
of a normal 1/4 wave spacing 4-square is .707 of a wavelength the
normal hard poly with a .66 velocity factor won't reach.

Dave
So my guess was close but what about the rest of the question. *Would
any odd multiple of a quarter wave work as well except for the
transmission losses it would introduce? Would three quarter waves
work?
--
Tom Horne. W3TDH- Hide quoted text -

- Show quoted text -

i 'think' so. since it adds an extra 1/2 wave delay to each of the
elements and should result in the same impedance transformation it
should work ok. it may be a bit more narrow banded since the
impedance transformation would change faster with frequency, but
probably not enough to notice.