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1/2 wave resonant inverted v dipole ?

Cold War Vet

Cold War Vet

KI7RPM
Aug 30, 2017
59
38
28
62
tucson az
1st off my Tech class licence test is set for nov 2nd my general is set for a month later this is due to paydays
3rd to every on here that has given me answers to my questions
THANK YOU ALL !!!!!

i recently purchased a Kenwood Ts120S HF SSB rig for 140$ it seems to work fine of course i cannot test xmit but receives fantastic on my random wire have heard maritime mobile radio SSB on 40M and cw on several diff bands 80,40 and 15 Meters so barring any finals issues ill be on the air soon

now for the caveat
i have been reading everything on 1/2 wave dipoles i can my lot size is very limited so i chose to do a resonant dipole starting at 40 meters using 2nd,3rd and 4th harmonics to give me 20M,15M and 10M and deal with 80 meters later
so i got a Rhone 40 tower given to me that put me 30 ft above my roof line the length of my house is 56'
the supports at each end of my house are 8' tall giving me 12 extra feet so 56'+12'=68'/2=34'
on each side
so for 20M 16' each 15M 11' each and 10M 8' each

they all resonate amongst themselves due to 2nd 3rd and 4th Harmonics except for the 15 M which is stand alone
oh and did i mention its all RG-6 75ohm coax 18ga copper center conductor and copper braid (not aluminum)

are my calculations wrong ? did i miss something?am i way off base ?

i believe a choke on the feed line will help reduce voltage on the outer casing
any input is appreciated
THX CWV
 
Last edited:

15 is the 3rd (odd) harmonic of 40 meters, you should be able to load the lower part of 15 quite easily.

I think you will find that the 2nd & 4th (even) harmonics will have a very high feedpoint impedance.

or,.... it's not really clear in your post, are you building a fan dipole with multiple radiators?

At this point, it may be a little too much to construct a (shortened) loaded dipole.

goodluck
 
Since you have ~34ft to work with, I would make a parallel (aka fan) dipole for 40/20 (and the 40 will cover 15). You could add 10m as well but I wouldn't suggest doing that later.

ETA, as RS referenced, it is not clear what you are building.
 
Stretch out a dipole as long as you can without having the ends on the ground or in the trees. Keep both legs as perfectly symmetrical as possible. Feed it with open feedliine and use it on all of the bands with the proper tuner.

Resonant antennas are overrated. Something like a g5rv is a great multiband antenna if you throw the cowaxe in the trash and connect the window line to a balanced tuner. If a coax fed dipole has a high swr you can use a tuner and talk on it but the coax loss can be extremely high. Not an issue with open feeders.

They should let you take the general after you pass the tech without paying again. It's up to the VE's though.
 
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Tallman,Road squawker and TBA02
yep i didnt specify sorry for that
but it is a multi fan center fed Dipole
i have to learn to be more clear in my typing

thanks all CWV
 
t
543_Dallas said:
Stretch out a dipole as long as you can without having the ends on the ground or in the trees. Keep both legs as perfectly symmetrical as possible. Feed it with open feedliine and use it on all of the bands with the proper tuner.

Resonant antennas are overrated. Something like a g5rv is a great multiband antenna if you throw the cowaxe in the trash and connect the window line to a balanced tuner. If a coax fed dipole has a high swr you can use a tuner and talk on it but the coax loss can be extremely high. Not an issue with open feeders.

They should let you take the general after you pass the tech without paying again. It's up to the VE's though.
Click to expand...

Thanks Dallas my issue with open feed line is my rig is on a wall on the opposite side of the room and my 101 (law enforcement code for wife) will certainly have a issue with it
 
A coax fed fan dipole will work just fine to get you started.
Resonant antennas *may* be overrated but ease of use once you have them working go a long way to enjoying yourself in the early stages of HF.

- sorry 543, not discounting your advice, just sharing my own experiences.
And yes, I have a tuner and use it! I also love just knowing my 40/20 is set and turning on and transmitting w/o a care as it suits my operating style w/ regard to home life.

ETA - I also have a stucco house, small lot and lots of wire fencing. Balanced line is a pain in the butt!
 
tba02 said:
A coax fed fan dipole will work just fine to get you started.
Resonant antennas *may* be overrated but ease of use once you have them working go a long way to enjoying yourself in the early stages of HF.

- sorry 543, not discounting your advice, just sharing my own experiences.
And yes, I have a tuner and use it! I also love just knowing my 40/20 is set and turning on and transmitting w/o a care as it suits my operating style w/ regard to home life.

ETA - I also have a stucco house, small lot and lots of wire fencing. Balanced line is a pain in the butt!
Click to expand...

It it works for you that's all that matters. I like to build things and sometimes forget that it isn't for everyone. I live in the city and don't have a lot of antenna room. One doublet fed with ladder line with my home brew tuners at the base of the tower allow me to use 80-6 with the same antenna. One has a gear reduction motor on the vac variable and I can move up and down 80 meters as needed without going outside. The bandwidth is sufficient on the rest of the bands and re tuning isn't necessary. I hear so many people that think a resonant antenna is the end all be all antenna. I disagree with that because a dipole can have gain on some bands and be used on all bands with the proper feed line and tuner.
 
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543_Dallas said:
... edit... a g5rv is a great multiband antenna if you throw the cowaxe in the trash and connect the window line to a balanced tuner....
Click to expand...

What you describe is not a G5RV, its a doublet. A G5RV is a single band 20 meter antenna.

A G5RV sucks ( a highly technical term) as a mulitband antenna.
 
It it works for you that's all that matters.
Click to expand...
Agreed.
I like to build things
Click to expand...
Me too!
I live in the city and don't have a lot of antenna room.
Click to expand...
Tell me about it! :)
One doublet fed with ladder line with my home brew tuners at the base of the tower allow me to use 80-6 with the same antenna.
Click to expand...
Ladder line is troublesome for my QTH.
Here's what I'm talking about -
[photo="medium"]4383[/photo] [photo="medium"]3964[/photo]
 

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