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the antenna gods seem to hate me... 10m/20m, Inverted V, fan dipole will not work
- Thread starter mr_fx
- Start date
well they fan out actually, the final separation is several feet with each band having it's own tie off point
I really don't get this, why would the antenna have low resistance? and high reactance?
I decided to rebuild it and move it to another location... well I also added 40m to the mix... 40/20/10 I give up I think
13Mhz was he best match I could find
Resistance = 22 Reactance = 62 and SWR = 2.9
WTH is going on here?
I decided to rebuild it and move it to another location... well I also added 40m to the mix... 40/20/10 I give up I think
13Mhz was he best match I could find
Resistance = 22 Reactance = 62 and SWR = 2.9
WTH is going on here?
The KJ4IIF Multiband "FAN" Dipole for 160, 80 and 40 Meters
follow this one, i have made four of these antennas and they definitively get you in the ball park.
You will start with the lowest band, the longest wire and tune it to resonance, then move to the next one etc etc.
separate the feed points by 12", separate the ends by 36".
If you tie all your legs together at one point they get wacky, by separating them at the feed point they tend to not have to much interaction or mutual coupling.
any more question drop me a pm and we can discuss it on the phone.
you will get it and it works good. just keep working on it.
follow this one, i have made four of these antennas and they definitively get you in the ball park.
You will start with the lowest band, the longest wire and tune it to resonance, then move to the next one etc etc.
separate the feed points by 12", separate the ends by 36".
If you tie all your legs together at one point they get wacky, by separating them at the feed point they tend to not have to much interaction or mutual coupling.
any more question drop me a pm and we can discuss it on the phone.
you will get it and it works good. just keep working on it.
Update: the issue is the MFJ antenna analyzer, is getting wiped out by local interference and or an AM broadcast station.
http://www.bvarc.org/Tech/BlameItOnIZO.pdf
example:
Frequency / SWR / instrument
14.350 / 12.4 / MFJ 259b
14.350 / 3.5 / Radioshack SWR meter
28.350 / 13.1 / MFJ 259b
28.350 / 3.4 / SWR meter
http://www.bvarc.org/Tech/BlameItOnIZO.pdf
example:
Frequency / SWR / instrument
14.350 / 12.4 / MFJ 259b
14.350 / 3.5 / Radioshack SWR meter
28.350 / 13.1 / MFJ 259b
28.350 / 3.4 / SWR meter
Broadcast interference can indeed cause issues. A fellow I used to work with could not use his on VHF due to being in the shadow of a 100 Kw station on 94.9 MHz. Many users have problems using it on HF if they are fairly close to an AM station.
As for your question above:
"I really don't get this, why would the antenna have low resistance? and high reactance"
This is completely normal. Resistance and reactance are simply two different components that make up the total antenna impedance. it is not at all unusual to have an antenna that has a very low radiation resistance and a very high reactance. I had an inverted L antenna that on 160m presented something stupid like 4 ohms of radiation resistance and over 800 ohms of reactance. ..........yeah it needed a tuner. LOL.
As for your question above:
"I really don't get this, why would the antenna have low resistance? and high reactance"
This is completely normal. Resistance and reactance are simply two different components that make up the total antenna impedance. it is not at all unusual to have an antenna that has a very low radiation resistance and a very high reactance. I had an inverted L antenna that on 160m presented something stupid like 4 ohms of radiation resistance and over 800 ohms of reactance. ..........yeah it needed a tuner. LOL.
ok we are starting to see results.
7.0Mhz - 2.75:1 7.1Mhz - 1.9:1 7.2MHz - 1.6:1 7.3Mhz - 1.9:1
20m is between 3.5 and 4.2 (time to trim)
15m is 3.2 all across the band (not much I can do here, unless you count a tuner)
10m around 2.2 (still need to tune that band)
7.0Mhz - 2.75:1 7.1Mhz - 1.9:1 7.2MHz - 1.6:1 7.3Mhz - 1.9:1
20m is between 3.5 and 4.2 (time to trim)
15m is 3.2 all across the band (not much I can do here, unless you count a tuner)
10m around 2.2 (still need to tune that band)
well if I hop in my car I can get there in about 3-7 mins driving about 30-40 mph
other than my 10m ground plane and my 2m antennas, no
Try tuning the higher bands first. Tune your 10m antenna first until you get it as low as you can and then move on to 15m then 20m etc. If you try tuning them all at the same time or in reverse order you will go insane trying to make sense of what is going on. I did that but with therapy I was deemed fit to reenter society again. 
If you try tuning them all at the same time or in reverse order you will go insane trying to make sense of what is going on. I did that but with therapy I was deemed fit to reenter society again.
hahahahahhaha :w00t:
the 40m got a little better as I tuned the 20m, now the 40m gets as low as 1.5 and 20m looks like this:
14.0 = 1.6:1
14.1 = 1.7:1
14.2 = 1.9:1
14.35 = 2.75:1
another interesting thing is my Yaesu FT-857d says the SWR is even lower, never even reaching 2.0:1 on the 20m band... I guess all I have is a Radio Shack special SWR meter, but it has served me well so far
14.0 = 1.6:1
14.1 = 1.7:1
14.2 = 1.9:1
14.35 = 2.75:1
another interesting thing is my Yaesu FT-857d says the SWR is even lower, never even reaching 2.0:1 on the 20m band... I guess all I have is a Radio Shack special SWR meter, but it has served me well so far
7.0Mhz - 2.75 :1
7.1Mhz - 1.9 : 1
7.2MHz - 1.5 : 1
7.3Mhz - 1.9 : 1
14.0Mhz - 1.05 : 1
14.1Mhz - 1.05 : 1
14.2Mhz - 1.1 : 1
14.35Mhz - 1.2:1
I checked the SWR on the bottom of the CB band, channel 1 and saw 1.6:1
At that adjustment I found a 3.25:1 SWR at 28.000Mhz, and 3.9:1 29.7
after shortening the 10m legs of antenna by 3.5 inches (yes on both legs) I got 2.75:1 at 28.0Mhz, and 3.9:1 at 29.7Mhz and now CB channel 1 is 3.25:1 SWR
My guess is that the 10m legs of the antenna are now resonant somewhere above channel 23 on the CB and below 28.000Mhz...
long story short it works so far
7.1Mhz - 1.9 : 1
7.2MHz - 1.5 : 1
7.3Mhz - 1.9 : 1
14.0Mhz - 1.05 : 1
14.1Mhz - 1.05 : 1
14.2Mhz - 1.1 : 1
14.35Mhz - 1.2:1
I checked the SWR on the bottom of the CB band, channel 1 and saw 1.6:1
At that adjustment I found a 3.25:1 SWR at 28.000Mhz, and 3.9:1 29.7
after shortening the 10m legs of antenna by 3.5 inches (yes on both legs) I got 2.75:1 at 28.0Mhz, and 3.9:1 at 29.7Mhz and now CB channel 1 is 3.25:1 SWR
My guess is that the 10m legs of the antenna are now resonant somewhere above channel 23 on the CB and below 28.000Mhz...
long story short it works so far
I have to ask,.... with all this wire shortening, are you actually cutting the wire?
I usualy just fold it back on itself, and after I get it where I want it, I cut it off once.