Sidebar Sidebar
  • You can now help support WorldwideDX when you shop on Amazon at no additional cost to you! Simply follow this Shop on Amazon link first and a portion of any purchase is sent to WorldwideDX to help with site costs.

Homemade antenna Issue High SWR

The DB said:
This isn't what is being scanned. Look closely at the symbol between those numbers, 26.965 MHz was the center frequency, and he was sweeping 27.405 MHz out from that frequency in both directions. If he wants just the CB band, the first frequency should be 27.185 MHz, and the second should be 0.22 MHz. That being said, I would personally recommend going past the CB frequencies to some extent so I would increase the second to 0.44 MHz, with this number the middle half of the screen will be the CB band.

I did a quick check of the manual to confirm this.

Also, those vertical blue bars are spaced and sized that at first glance look like they are showing where the various ham bands are...


The DB
Click to expand...
I corrected that I messed up on that setting thank you
 
well now its 2.8 at 30mhz and 3.1 at 27205 my center lowest it will go I have to figure how to mess with that lower element to adjust it i don't want to cut then re assemble cut reassemble there has to be another way

OBTW I scan for x=0 and best I got was -2 @ 28.425
 
HomerBB said:
We can test the "way too short" theory pragmatically.
Get some aluminum foil and roll it like a tube around each end of the dipole. Attach it firmly for good contact using zip ties, rubber bands, etc.
Start way too long on both ends, then start sliding it inward both ends at a time same amount to see what happens.

Goofy idea? Call me goofy. I've done it more than once.

The same can be done with two antenna stingers and hose clamps.

He can always go back to a standard made dipole and a taller mast.

View attachment 39560 View attachment 39561 View attachment 39562

Two fishing poles and wire, or two tubes. The tube one was made of fence top rail.
Click to expand...
no go partner foil didnt work I even had some aluminum wire like around 8 gauge increase the swr Im lost
 
IM done I spent to much on this including the analyzer to make my own antennas Im just going to run down to the local Electronics and pick up a Maco V58 or a V5000 maybe just a Imax 2000 Im not sure yet Thank You all for your Time
 
If you get curious, to adjust the bottom tube I slide the bottom PVC nipple down along the coax cut off a little at a time with tubing cutters, snip through the little bit I trimmed with tin snips, spread the little piece open, remove it from around the coax, toss it, slide the PVC nipple back into place, and check the SWR.
 
  • Like
Reactions: Gunner357
I am sure some may not agree, but between your choices ppick one of those with radials.
When you assemble it follow directions. Don't deviate from them.
If you can't do that get the Imax 2000. That one is made in the 'Antennas for Dummies' factory in terms of assembly.
PS. When I have time I will make another of these vertical dipoles doing a step by step and post a thread just for folks like you.
Homer.
 
  • Like
Reactions: S&W357
HomerBB said:
I am sure some may not agree, but between your choices ppick one of those with radials.
When you assemble it follow directions. Don't deviate from them.
If you can't do that get the Imax 2000. That one is made in the 'Antennas for Dummies' factory in terms of assembly.
PS. When I have time I will make another of these vertical dipoles doing a step by step and post a thread just for folks like you.
Homer.
Click to expand...
Ya I'm probably going for the v58 I dont need a 5000 watt one. But yeah Homer thank you so much, Im really depressed over this, I really Like the plans too i think its the best plans Ive seen threw all the research ive been doing I really like the ones you made they look clean.... I have it hooked up right now Listening getting the skip Mi to GA MS and Barbados!!! but its partial covered by the house .... but dont know why 1:7 on the DOSEY And the radio but 3.1 on the Analyzer dont make sense too me
 
HomerBB said:
If you get curious, to adjust the bottom tube I slide the bottom PVC nipple down along the coax cut off a little at a time with tubing cutters, snip through the little bit I trimmed with tin snips, spread the little piece open, remove it from around the coax, toss it, slide the PVC nipple back into place, and check the SWR.
Click to expand...
How do you tune them standing off somewhere ... or set it up where it will be then match it etc
 
I usually build them to general specs then mount them at 21' feedpoint and tune them there. Then I raise them higher, usually to 34'. I work from this platform.20200310_170356.jpg

When I can not work from there on the platform I set a fiberglass step ladder in the yard with a 10' EMT pipe sticking up through it. Antenna is mounted on a smaller EMT pipe inside that one. I tune, then push the inner EMT tube up to get the antenna feedpoint to 19' height to take SWR sweeps.
 
  • Like
Reactions: Gunner357 and Slowmover
Gunner357 said:
Ya I'm probably going for the v58 I dont need a 5000 watt one. But yeah Homer thank you so much, Im really depressed over this, I really Like the plans too i think its the best plans Ive seen threw all the research ive been doing I really like the ones you made they look clean.... I have it hooked up right now Listening getting the skip Mi to GA MS and Barbados!!! but its partial covered by the house .... but dont know why 1:7 on the DOSEY And the radio but 3.1 on the Analyzer dont make sense too me
Click to expand...
Beats me. At 1.7 try communicating with it.
 
first thing I would do is put a dummyload at the end of the rg213 & make sure everything is as it should be, & a good match with no cmc on the braid actually gives you a near flat vswr at the analyzer/meter,

a copper tube dipole should tune no problem,
its fat so needs to be a little shorter than a bare wire,
its inside a plastic tube that adds dielectric loading & slows the vf a little so it need to be a little shorter than if it was in air,

you can't make proper measurements ( of the antenna feed-point ) without putting an effective choke just below the copper tube to isolate as best you can the coax braid been part of the antenna,

no choke causes vswr & pattern to change with coax length & position,

measuring your dipole through a random length coax won't tell you what's going on at the feed-point even if you have the best choke in the world & zero cmc on the braid

if you want to know about the antennas impedance & where its resonant your coax must be cut so its a multiple of electrical 1/2waves from the feed-point to your meter/analyzer on the frequency you want it tuned for,

anything other than electrical 1/2wave or multiple 1/2waves will transform the impedance seen looking into the analyzer end of coax and move the resonance point.

The user manual for your analyzer should explain why you can't use random length
coax for impedance & resonance measurements,

my buddy recently made the same antenna by converting a fat sirio 827 5/8wave groundplane into an aluminum 1/2wave dipole with no problem getting it tuned & working as well as any 1/2wave at the same height.
 
  • Like
Reactions: Slowmover, HomerBB and Gunner357

dxChat
Help Users
  • No one is chatting at the moment.


      Top Bottom
      Back