I spent the day lowering the folded dipole that I BOUGHT. I was unable
until recently to find how bad the SWR was on most bands. The only
reasonable SWR was on 17 meters.

So, I replaced it with a homemade G5RV, measured appropiately for each
leg of the dipole (14AWG) and for the 300 ohm window line to R/G8U.

I now find reasonable SWR on most bands (WARC, not so much). Here's the
deal: min SWR comes in right at 3.5 MHz, 6.75, 13.43, 18.07 and 29.06.
It appears that I made the classic newbie mistake...antenna too short.

Now, since I am using an ATU, I think this should be close enough for
acceptable efficiency (at least for 80, 40, 20, 17 and 10 meters).

What do you think?

John
AB8O

PS, When I get the time, I'll try EZNEC but for now, I just want to work
what I hear for a change (!)

"jawod" wrote in message
...
I spent the day lowering the folded dipole that I BOUGHT. I was unable
until recently to find how bad the SWR was on most bands. The only
reasonable SWR was on 17 meters.

So, I replaced it with a homemade G5RV, measured appropiately for each leg
of the dipole (14AWG) and for the 300 ohm window line to R/G8U.

I now find reasonable SWR on most bands (WARC, not so much). Here's the
deal: min SWR comes in right at 3.5 MHz, 6.75, 13.43, 18.07 and 29.06. It
appears that I made the classic newbie mistake...antenna too short.

Now, since I am using an ATU, I think this should be close enough for
acceptable efficiency (at least for 80, 40, 20, 17 and 10 meters).

What do you think?

John
AB8O
Looks as though the antenna is too long except for 10M.

Dale W4OP

Dale Parfitt wrote:
"jawod" wrote in message
...

I spent the day lowering the folded dipole that I BOUGHT. I was unable
until recently to find how bad the SWR was on most bands. The only
reasonable SWR was on 17 meters.

So, I replaced it with a homemade G5RV, measured appropiately for each leg
of the dipole (14AWG) and for the 300 ohm window line to R/G8U.

I now find reasonable SWR on most bands (WARC, not so much). Here's the
deal: min SWR comes in right at 3.5 MHz, 6.75, 13.43, 18.07 and 29.06. It
appears that I made the classic newbie mistake...antenna too short.

Now, since I am using an ATU, I think this should be close enough for
acceptable efficiency (at least for 80, 40, 20, 17 and 10 meters).

What do you think?

John
AB8O
Looks as though the antenna is too long except for 10M.


Dale W4OP


Dale,
Thanks for the response.
My god, you're right. I think I better get some sleep!

Thanks,

John
AB8O

PS, question still holds...I think I can leave it as is using an ATU, No?

On Tue, 26 Sep 2006 23:57:56 -0400, jawod wrote:

I spent the day lowering the folded dipole that I BOUGHT. I was unable
until recently to find how bad the SWR was on most bands. The only
reasonable SWR was on 17 meters.

So, I replaced it with a homemade G5RV, measured appropiately for each
leg of the dipole (14AWG) and for the 300 ohm window line to R/G8U.

I now find reasonable SWR on most bands (WARC, not so much). Here's the
deal: min SWR comes in right at 3.5 MHz, 6.75, 13.43, 18.07 and 29.06.
It appears that I made the classic newbie mistake...antenna too short.


Have a look at Fig 4 at http://www.vk1od.net/G5RV/index.htm . Though
the graph doesn't show VSWR on the RG213, the loss is lowest where the
VSWR is lowest. You should be using an ATU, and it is the line loss
that is more important than the VSWR of itself.

Your antenna sytem appears a little long rather than short, did you
measure the length of the radiator conductors, did you measure the 300
ohm line, did you allow for the velocity factor of the 300 ohm line?

Owen


Now, since I am using an ATU, I think this should be close enough for
acceptable efficiency (at least for 80, 40, 20, 17 and 10 meters).

What do you think?

John
AB8O

PS, When I get the time, I'll try EZNEC but for now, I just want to work
what I hear for a change (!)
--

Most of those lowest SWR points actually indicate the elements are too
LONG. Remember, the wavelength is longer as frequency is lower.

jawod wrote:
I spent the day lowering the folded dipole that I BOUGHT. I was unable
until recently to find how bad the SWR was on most bands. The only
reasonable SWR was on 17 meters.

So, I replaced it with a homemade G5RV, measured appropiately for each
leg of the dipole (14AWG) and for the 300 ohm window line to R/G8U.

I now find reasonable SWR on most bands (WARC, not so much). Here's the
deal: min SWR comes in right at 3.5 MHz, 6.75, 13.43, 18.07 and 29.06.
It appears that I made the classic newbie mistake...antenna too short.

Now, since I am using an ATU, I think this should be close enough for
acceptable efficiency (at least for 80, 40, 20, 17 and 10 meters).

What do you think?

John
AB8O

PS, When I get the time, I'll try EZNEC but for now, I just want to work
what I hear for a change (!)

jawod wrote:
I now find reasonable SWR on most bands (WARC, not so much). Here's the
deal: min SWR comes in right at 3.5 MHz, 6.75, 13.43, 18.07 and 29.06.
It appears that I made the classic newbie mistake...antenna too short.

Actually, it appears to be too long on 75m, 40m, and 20m.
--
73, Cecil http://www.w5dxp.com

Cecil Moore wrote:
jawod wrote:

I now find reasonable SWR on most bands (WARC, not so much). Here's
the deal: min SWR comes in right at 3.5 MHz, 6.75, 13.43, 18.07 and
29.06. It appears that I made the classic newbie mistake...antenna too
short.


Actually, it appears to be too long on 75m, 40m, and 20m.

Thanks to all for replies.

Yep, too LONG.
Egg on MY face. In my defense, it was late and I was working all day
getting the G5RV up in the trees.

To top off the day, I connected my K2 to the ATU and can't get them to
work together...short somewhere...will have to wait until after work.

John
AB8O

jawod wrote:
Yep, too LONG.
Egg on MY face. In my defense, it was late and I was working all day
getting the G5RV up in the trees.

The dipole should be 102 feet for bare wire. Maybe 99
feet for insulated wire. That's 1.5WL on 20m. The
series section should be 1/2WL on 20m. With a VF = 0.9,
that's a little over 31 feet.

According to EZNEC, here are the optimum lengths for
the series section:

3.8 MHz 30.5', 7.2 MHz 34.5', 10.125 MHz 20.7',
14.2 MHz 33', 18.14 MHz 12.5' or 37',
21.3 MHz 29.5', 24.95 MHz 30.5', 28.4 MHz 23.4'

It's easy to see why 31' doesn't work well on
30m, 17m, and 10m.
--
73, Cecil http://www.w5dxp.com

"jawod" wrote in message
...
I spent the day lowering the folded dipole that I BOUGHT. I was unable
until recently to find how bad the SWR was on most bands. The only
reasonable SWR was on 17 meters.

So, I replaced it with a homemade G5RV, measured appropiately for each leg
of the dipole (14AWG) and for the 300 ohm window line to R/G8U.

I now find reasonable SWR on most bands (WARC, not so much). Here's the
deal: min SWR comes in right at 3.5 MHz, 6.75, 13.43, 18.07 and 29.06. It
appears that I made the classic newbie mistake...antenna too short.

Now, since I am using an ATU, I think this should be close enough for
acceptable efficiency (at least for 80, 40, 20, 17 and 10 meters).

What do you think?

John
AB8O

PS, When I get the time, I'll try EZNEC but for now, I just want to work
what I hear for a change (!)

You might want to try 450 Ohm line instead of the 300. On Eznec, it works
out better.

Tam/WB2TT

Cecil Moore wrote:
jawod wrote:

Yep, too LONG.
Egg on MY face. In my defense, it was late and I was working all day
getting the G5RV up in the trees.


The dipole should be 102 feet for bare wire. Maybe 99
feet for insulated wire. That's 1.5WL on 20m. The
series section should be 1/2WL on 20m. With a VF = 0.9,
that's a little over 31 feet.

According to EZNEC, here are the optimum lengths for
the series section:

3.8 MHz 30.5', 7.2 MHz 34.5', 10.125 MHz 20.7',
14.2 MHz 33', 18.14 MHz 12.5' or 37',
21.3 MHz 29.5', 24.95 MHz 30.5', 28.4 MHz 23.4'

It's easy to see why 31' doesn't work well on
30m, 17m, and 10m.
Yep, that's about right. I cut it at 51 x2 = 102 feet but I used
insulated wire...so if I want to bring down the antenna to correct it, I
should remove about 18 inches per side, right?

Pretend, for a minute, that I am NOT an antenna "purist" (not too hard a
task, you say?)

....Do I want to go out and correct it or just let the ATU compensate?