On Fri, 10 Aug 2007 22:18:19 -0700, "Sal M. Onella"
wrote:

My friend had a 4-element 2m quad with dangerously high VSWR. Somebody gave
it to him (which I guess was the first sign). Yesterday, he brought it by
for me to check it out.


I love this hobby!

"Sal"
(KD6VKW)

Don't overlook that you can parallel two quads to get to 50 ohms as
well!

There is no end to the fun with VHF Quads. About any kind of sticks,
wire and tape will get you going. Don't forget to keep notes, they are
very useful as the learning accelerates.

John Ferrell W8CCW
"Life is easier if you learn to
plow around the stumps"

[After sending this, I never saw it posted so I re-sent. Sorry if it's a
dupe in your newsreader.]

"John Ferrell" wrote in message
...



Don't overlook that you can parallel two quads to get to 50 ohms as
well!


OK, I took a mental excursion in that direction. My first thought is to use
two runs of RG-62 93-ohm computer drop cable off a t-connector. This goes
against my grain -- I've always hated using any t-connectors in a matched
system -- but I guess the match will be maintained.

My second thought is to literally parallel them at the end of a hunk of
50-ohm cable. That feed would need to be crossed over, I think, so the
fields would be additive. Easy enough to test it both ways, I suppose. If
crossover is needed, what would the pattern look like without it? Hm-m-m-m
.... near-field cancellation and no pattern? Pattern rotation?

Of course I will be trying this next idea even if no newsgroup answer is
forthcoming: What happens if I tap off quad #1 on the side _opposite_
where I'm feeding it and connect quad #2 there? Wouldn't this additional
load reflect back to feed #1 and lower its impedance toward 50 ohms? I
don't know what feed #2 would be. Perhaps a jury-rig parallel line
calculated to be 100 ohms would do it. (# 10 AWG wires on 5 mm centers would
do it.) Phasing will be an issue.
[I probably don't have a suitable test environment to tell success from
failure.]

73,
"Sal"

Of course I will be trying this next idea even if no newsgroup answer is
forthcoming: What happens if I tap off quad #1 on the side _opposite_
where I'm feeding it and connect quad #2 there? Wouldn't this additional
load reflect back to feed #1 and lower its impedance toward 50 ohms? I
don't know what feed #2 would be. Perhaps a jury-rig parallel line
calculated to be 100 ohms would do it. (# 10 AWG wires on 5 mm centers would
do it.) Phasing will be an issue.
[I probably don't have a suitable test environment to tell success from
failure.]

73,
"Sal"


It is easier and cheaper to do phasing/matching harnesses with open
wire. Make it, don't buy it. Considering that a 1/4 wave is only about
19 inches you can make experiments with whatever wire is handy using
popsicle sticks ("craft sticks" at the craft store) and masking
tapefor the spacers.

Make a field strength meter with a diode and dipole connected to a
multi meter. space it about 30 feet in front of the quad. While
transmitting verify the elements are all working by touching each
element with a screwdriver.

Operate the transmitter at lowest possible power.

Too much fancy equipment gets distracting.

John Ferrell W8CCW
"Life is easier if you learn to
plow around the stumps"

"John Ferrell" wrote in message
...



Don't overlook that you can parallel two quads to get to 50 ohms as
well!


OK, I took a mental excursion in that direction. My first thought is to use
two runs of RG-62 93-ohm computer drop cable off a t-connector. This goes
against my grain -- I've always hated using any t-connectors in a matched
system -- but I guess the match will be maintained.

My second thought is to literally parallel them at the end of a hunk of
50-ohm cable. That feed would need to be crossed over, I think, so the
fields would be additive. Easy enough to test it both ways, I suppose. If
crossover is needed, what would the pattern look like without it? Hm-m-m-m
.... near-field cancellation and no pattern? Pattern rotation?

Of course I will be trying this next idea even if no newsgroup answer is
forthcoming: What happens if I tap off quad #1 on the side _opposite_
where I'm feeding it and connect quad #2 there? Wouldn't this additional
load reflect back to feed #1 and lower its impedance toward 50 ohms? I
don't know what feed #2 would be. Perhaps a jury-rig parallel line
calculated to be 100 ohms would do it. (# 10 AWG wires on 5 mm centers would
do it.) Phasing will be an issue.
[I probably don't have a suitable test environment to tell success from
failure.]

73,
"Sal"

"Sal M. Onella" wrote in message
...

"John Ferrell" wrote in message
...



Don't overlook that you can parallel two quads to get to 50 ohms as
well!


OK, I took a mental excursion in that direction. My first thought is to
use
two runs of RG-62 93-ohm computer drop cable off a t-connector. This goes
against my grain -- I've always hated using any t-connectors in a matched
system -- but I guess the match will be maintained.

My second thought is to literally parallel them at the end of a hunk of
50-ohm cable. That feed would need to be crossed over, I think, so the
fields would be additive. Easy enough to test it both ways, I suppose.
If
crossover is needed, what would the pattern look like without it?
Hm-m-m-m
... near-field cancellation and no pattern? Pattern rotation?

Of course I will be trying this next idea even if no newsgroup answer is
forthcoming: What happens if I tap off quad #1 on the side _opposite_
where I'm feeding it and connect quad #2 there? Wouldn't this additional
load reflect back to feed #1 and lower its impedance toward 50 ohms? I
don't know what feed #2 would be. Perhaps a jury-rig parallel line
calculated to be 100 ohms would do it. (# 10 AWG wires on 5 mm centers
would
do it.) Phasing will be an issue.
[I probably don't have a suitable test environment to tell success from
failure.]

73,
"Sal"



Stacking two 100 ohm impedance quads is electrically about as easy as it
gets. An electrical 1/4wl of any good quality coax from each antenna to a T.
50 ohm cable to the shack.


Jimmie.

"Jimmie D" wrote in message
...


Stacking two 100 ohm impedance quads is electrically about as easy as it
gets. An electrical 1/4wl of any good quality coax from each antenna to a
T.
50 ohm cable to the shack.

Thanks. I would've thought it needed to be 1/4w/l of 75-ohm cable, but
I'll try it.

"Sal M. Onella" wrote in
:


"Jimmie D" wrote in message
...


Stacking two 100 ohm impedance quads is electrically about as easy as
it gets. An electrical 1/4wl of any good quality coax from each
antenna to a
T.
50 ohm cable to the shack.

Thanks. I would've thought it needed to be 1/4w/l of 75-ohm cable,
but
I'll try it.

You are right to question to advice Sal.

Of course with a 1/4wl with VSWR=2, the Zo does matter.

However, Jimmie might have meant each leg to be a 1/2wl (electrical)...
close wasn't it! In that case, Zo isn't critical.

Owen

"Owen Duffy" wrote in message
...
"Sal M. Onella" wrote in
:


"Jimmie D" wrote in message
...


Stacking two 100 ohm impedance quads is electrically about as easy as
it gets. An electrical 1/4wl of any good quality coax from each
antenna to a
T.
50 ohm cable to the shack.

Thanks. I would've thought it needed to be 1/4w/l of 75-ohm cable,
but
I'll try it.

You are right to question to advice Sal.

Of course with a 1/4wl with VSWR=2, the Zo does matter.

However, Jimmie might have meant each leg to be a 1/2wl (electrical)...
close wasn't it! In that case, Zo isn't critical.

Owen

Owen you are a good mind reader, sorry about the typo, should have been 1/2
wl.


Jimmie

"Jimmie D" wrote in message
...

"Owen Duffy" wrote in message
...
"Sal M. Onella" wrote in
:


"Jimmie D" wrote in message
...


Stacking two 100 ohm impedance quads is electrically about as easy as
it gets. An electrical 1/4wl of any good quality coax from each
antenna to a
T.
50 ohm cable to the shack.

Thanks. I would've thought it needed to be 1/4w/l of 75-ohm cable,
but
I'll try it.

You are right to question to advice Sal.

Of course with a 1/4wl with VSWR=2, the Zo does matter.

However, Jimmie might have meant each leg to be a 1/2wl (electrical)...
close wasn't it! In that case, Zo isn't critical.

Owen

Owen you are a good mind reader, sorry about the typo, should have been
1/2 wl.

Not to mention you would never get enough space between the antennas using
1/4wl sections.

Don't overlook that you can parallel two quads to get to 50 ohms as
well!



Much simpler solution, build 3 element quad with wide spaced elements and
you get 50 ohm impedance, good pattern/gain and simple antenna.

Yuri K3BU.us