antenna tuning

[kk4fpx]

I finally got around to checking swr on my Inverted v fan dipole antenna.On the 10 meter segment the swr is 1:3 can't check the 40 meter on this meter as it's for CB.Any ideas on how I should go about lowering it?

[NQ6U]

Unfortunately, we need a little more data. Without knowing the antenna's resonant frequency, it's hard to give any advice. However, that CB meter should be okay across the bands as long as you keep the wattage in low.

[kk4fpx]

The 10 meter is cut for 28.400 MHz and the 40 meter for 7.075 hHz.

[N2CHX]

1.3:1 is acceptable and that CB meter should be pretty accurate all the way down to 80 or even 160 meters. It's going up in frequency that would be a problem.

[NQ6U]

1.3:1 is acceptable and that CB meter should be pretty accurate all the way down to 80 or even 160 meters. It's going up in frequency that would be a problem.

He said 1:3, though, that's pretty high. Craig, I figure your antenna should be about 16' 6" long overall, is that what you have there? And how are you feeding it?

[WØTKX]

1.3 is a high swr? That's about a 2% power loss. No big deal. Even with a 4 watt output QRP radio ( ;) ) that's a loss of approx .1 watt. The coax itself probably has more loss. And at a 100 watts or so, no big deal. Check your SWR with the CB meter, it will work just fine.

If you're gonna get that fussy, I'd suggest some magic (note the credits at the bottom :lol: ):

http://3.bp.blogspot.com/_b-S9eayK7rw/Sqr4Zazh79I/AAAAAAAAADs/msJAg3KJrWM/s1600/D3Z-500px-72dpi.jpg

[NQ6U]

1.3 is a high swr? That's about a 2% power loss. No big deal.

True, but he said 1:3, not 1.3.

[WØTKX]

OK, my bad. I read it wrong. Unless he's running a pi-network tank output (tubular style) that's not good.

[kk4fpx]

The antenna is 16'6" but I used insulated wire and left about 6" more to wrap around the insulator so It might be a little too long.and I may have stated the swr reading wrong the meter swings up to the 3 mark on transmit.

[NQ6U]

Yeah, it sounds like it probably is too long. Using insulated wire has the effect of lengthening the antenna electrically, for one thing. Better that than it being too short, though, because it's a lot easier to fix. Just start clipping the wire at each end maybe 1/4"-1/2" at a time and check the SWR after each trim.

[KJ3N]

How high is the antenna, and is it a flattop or inverted vee?

A dipole 16.5 feet long and 30 feet up should be resonant @ close to 28.900. If anything, it might be too short. Adding just 3 inches to the length (16.75 feet long) should make it resonant @ 28.400.

[N2CHX]

He said 1:3, though, that's pretty high. Craig, I figure your antenna should be about 16' 6" long overall, is that what you have there? And how are you feeding it?

Yeah you're right. I saw it as 1.3 and thought he meant 1.3:1, because normally you would say 3:1 not 1:3. 1:3 would be one heck of an efficient antenna.

[WØTKX]

Ayup. And hiya Kelli.

[N2CHX]

Ayup. And hiya Kelli.

Sawatde kaa Dave.

[kk4fpx]

It's about 25 feet high and it's an inverted vee.

[W2NAP]

to bad you didnt have a MHF 259 or 269. that would tell you alot and be very helpful and handy

also Hi Kelli

[NQ6U]

to bad you didnt have a MHF 259 or 269. that would tell you alot and be very helpful and handy

also Hi Kelli

Yeah, I love my 259. Best two hunnert bucks I ever spent on ham gear.

And hello to you Kelli, good to see you back on the Island.

[ad4mg]

It's about 25 feet high and it's an inverted vee.

If you would take SWR readings at 3 different frequencies and post them here, any number of these folks could tell you what corrective action to take. Take readings at 28.000, 28.300, and 28.500 and post them here. Kelli is correct, the SWR you are reporting should be stated as 3:1 to avoid confusion.

I have a rotatable 10m dipole made from EMT conduit, and each element is 8'-3" long. I built it long ago, and was primarily interested in the CW portion of the band. I believe I used 28.150 as the intended center frequency, so that may be a little long if you are primarily a SSB operator.

As Jim pointed out at the top of this page, height above ground, and even surrounding objects will all affect your SWR.

[ki4itv]

*might want to use somebody else's callsign on that 28.000 test though.;):lol:

[KJ3N]

*might want to use somebody else's callsign on that 28.000 test though.;):lol:

No need to. Things change (http://www.arrl.org/files/file/Hambands_color.pdf). Recheck the 10m Tech privileges.

[ki4itv]

Damn if they don't. :dunno:
Some day's I'm just not thinking...

[kk4fpx]

28.000=2:1
28.300=2.9:1
28.500=3.1:1

[N2CHX]

28.000=2:1
28.300=2.9:1
28.500=3.1:1

Lucky for you, it's too long. Start trimming a half-inch to an inch at a time and check the reflected power in between trimmings until it's acceptable. Better to trim too little than too much, so take it slow.

With those numbers I'm gonna guess it's about 6 inches too long. That's just my guess.

Oh yeah and hey 'IBC and Carl. :-)

[kk4fpx]

Thanks I'll start triming the first of the week!

[kk4fpx]

I guess I owe N2KKM a dinner.It was almost 6" too long.
New readings.
28.300=1.1:1
28.500=1.3:1

[WØTKX]

Now you're in bidness! :clap:

[N2CHX]

I guess I owe N2KKM a dinner.It was almost 6" too long.
New readings.
28.300=1.1:1
28.500=1.3:1

Awesome!!

[NQ6U]

Anything below 2.0:1 is good; 1.3:1 is golden. You are good to go!

[kk4fpx]

I talked to Zl1PB in New Zealand a little while ago and he told me he could understand me this time!

[KA9MOT]

Now that you've solved the problem on the 10M wire, you need to go back and check the other bands. There is some interaction between the bands on a fan dipole. Use the meter you have and keep your power low. That CB meter will get you close.

[kb2vxa]

Now why did you go and mess up a perfectly good CB antenna?

[KG4NEL]

1.3 is a high swr? That's about a 2% power loss. No big deal. Even with a 4 watt output QRP radio ( ;) ) that's a loss of approx .1 watt. The coax itself probably has more loss. And at a 100 watts or so, no big deal. Check your SWR with the CB meter, it will work just fine.

If you're gonna get that fussy, I'd suggest some magic (note the credits at the bottom :lol: ):

http://3.bp.blogspot.com/_b-S9eayK7rw/Sqr4Zazh79I/AAAAAAAAADs/msJAg3KJrWM/s1600/D3Z-500px-72dpi.jpg

:hyper:

I need that in a sticker... :)

[WØTKX]

K1NSS made that amusing artwork.

http://www.dashtoons.com/

We're rather tickled that he hangs out on The Island.

[kk4fpx]

KA9MOT said:Now that you've solved the problem on the 10M wire, you need to go back and check the other bands. There is some interaction between the bands on a fan dipole. Use the meter you have and keep your power low. That CB meter will get you close.


I'm almost afraid to.Maybe later.

[n2ize]

He said 1:3, though, that's pretty high. Craig, I figure your antenna should be about 16' 6" long overall, is that what you have there? And how are you feeding it?

1.3 isn't bad. In the old day's a lot of hams used to operate at much higher swr's and they still "worked the world'".

[K7SGJ]

1.3 isn't bad. In the old day's a lot of hams used to operate at much higher swr's and they still "worked the world'".


When I first got on and for many years after, I never had a clue what my swr was and I had a great time working stations all over. Then, in later years when I could afford a meter, I adjusted my antennas for the best possible swr and couldn't work shit. Some things in life are better left unknown.

[KJ3N]

When I first got on and for many years after, I never had a clue what my swr was and I had a great time working stations all over. Then, in later years when I could afford a meter, I adjusted my antennas for the best possible swr and couldn't work shit. Some things in life are better left unknown.

A dummy load has a great SWR. Doesn't make a lot of contacts, however.

[NQ6U]

A dummy load has a great SWR. Doesn't make a lot of contacts, however.

I have made two—when when a local ham was on his dummy load and once when I was sending out a CW CQ into mine while testing out the T-4X. Both surprised the hell outta me.

[WØTKX]

I worked Milwaukee WI as a novice on 15 meters when I was testing with a light bulb. Band was "closed" :lol:

He gave me a 439C. I was grinding and testing crystals... he heard me after I found a "bad one".

[PA5COR]

Running 1.5 watt in a wire of 9 feet on the workbench testing a repaired transceiver, Netherlands to Washington USA on 10 meters got 5/9...