Dual Band 2m / 70cm vertical dipole BUILD #2 Part 2 of 4
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- เผยแพร่เมื่อ 15 ก.ย. 2024
- Continuation of building the second iteration of my dual band vertical dipole antenna
The lengths, measured from the outside of the bottom bend, are:
6 1/4" for the 70cm side
18 5/8" for the 2m side
A newer ham may not realize, but a soldering gun may be more useful when soldering on coax as it is less likely to melt the dielectric. This has been my experience anyway. Great series of videos! 73 KD8TAE
I am a new ham, and am looking at ideas to build my first antenna. I like this design, but I have one question. On the T portion, do you need to waterproof that? Could you just solder the whole thing up to the rubber and waterproof it that way, or is that a bad idea?
I'm not sure what point you're talking about as far as "soldering up to the rubber". If you mean tinning the center and shield back to where they split out of the coax the solder wouldn't be waterproofing the conductors. It would be leaving them exposed to the elements and so corrosion would begin as soon as any moisture was introduced....even just some dew drops.
Waterproofing things protects them from the moisture and increases the time it takes for corrosion to affect things.
Corrosion is inevitable. It is the material attempting to return to its natural state before having been mined, refined, and turning into the product we want. Moisture, dissimilar metals, any non neutral PH, all just help the process along.
Why wouldn't you solder the center of the coax to the SO-239 before mounting it into the box? I would do it a little bit different and prob. use a step drill as well.
I felt that doing the SO239 soldering last would be best in case I had issues with separating the coax at the element end and attaching the ring connectors.
Hey there. Do you think you could use an so 239 to so239 female adapter instead of cutting the end of the cable and soldering at the CPVC T section? What does still provide a proper ground for the dipole antenna?
You could do that though I'm not sure what advantage it would be other than if you just don't have an SO-239 chassis connector available.
Dipole antennae do not require a ground to function. If you are talking about a lightening protection ground, that would need to be attached into the shield side at some point.
Would RG-59 coax work just as well? I have plenty of it. And would aluminum welding rods work as well also? Thanks for the video series.
If RG59 is 50 ohms it should work. Aluminum rod will work but the theoretical length will be different. In practice however, I don't find that material makes a difference. This is because the difference in length due to velocity factor is so small when working with such short wavelengths.
Why can’t you make you cable connections inside the tee so all congratulations are weather proof?
I considered it but went with the current design for simplicity and to minimize the amount of conductor before the actual stainless elements.
Why didn't you put the coax wire inside the tube?
I did put the coax inside the tube except at the point where they attach to the elements.
Had you thought of attaching the coax from inside the tee? Or do you think the curvature will prevent a good connection.
Well I thought I'd already answered this but I don't see a response. Things that were investigated were:
Attaching the coax on the other end of the bolts so that only the elements would be exposed to the tightening and loosening cycles. As expected, this didn't work due to lengthening the electrical path and turning the bolts into part of the elements. It might work if the elements themselves were shortened to compensate but I don't think it would be as efficient.
Using shorter bolts that only went through one side of the T and attaching the coax on the inside of the T but I felt that could allow a loose connection to develop over time as well as being less sturdy and subject to failure due all stresses being placed on only one side of the T.
Bringing the Coax through a standard T and then down the inside of the upper section of the mast, possibly to another T for mounting. This was looked at as a cost savings measure for a potential group build but I decided it could introduce more difficulty in the build as well as another potential weak spot at the joints and would cause the length of RG58 to be longer, thus inducing more loss (though it is minimal in such a short length).
Ok, very reasonable. Really great set of videos. Thanks. KB4ANV
No Problem. I'm busy teaching a Tech/General course but plan to do some more antenna videos soon. Might even build another bucket swamp cooler 9great for Field Day).
So did you use stainless steel? I don't remember hearing you say. lmao 🤣
Yes they are stainless steel TIG welding rods.
do you have the plans anywhere for this?
I don't have plans. If you watch all four parts it will give you all the information you need.
haha not so good with engineering skills 10 min job over an hour in 4 parts .
With very detailed, step by step, instructions so that those who don't have a lot of hands on build experience can be successful on their first attempt.
Not sure why you felt it necessary to make a derogatory comment but hey, some people gotta hate.