Can Adding a Metal Mast Disrupt an Antenna? (
Stacy Pharis, KI5MIT, has a homebrew antenna very similar in concept to the DX Commander, all held up by a tree. She wants to know if using a metal mast to hold it up would create issues. Yes, it would. Watch to find out why.
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Thanks for another great show. You answer the questionsmost people are afraid to ask. Yoiu do it a kind and simple to understand way. You are the ELMER of youtube.
This is a very supportive video.... They wanted to know how to improve it and you were like this better than what most people have
I have often thought about the same idea that Stacy is implementing but so far haven't taken the time to do it. Great to hear she is having success! 73, KJ7FEE
I have a 20/40 meter inverted Vee Fan Dipole and it is supported in the center by an MFJ heavy duty telescoping fiberglass pole. Works great. I have trouble getting it to load on 15 meters. I get an SWR of about 3.0. Replacing some older coax and will put a 1:1 current balun in the center and hope that makes it more efficient. My coax has too many connectors and the coax is too long. I'll retune it after I've replaced the coax. Really enjoy your videos!
@davecasler
2 жыл бұрын
In the long-gone good old days, people would often load up a 40 meter dipole on 15. I certainly did. But with modern rigs, using 15 on a 40 meter dipole will often be presented with a high SWR. I did a video on that subject not terribly long ago.
One of the best antennas I ever put together was a "parallel fan" 40m/ 20m dipole similar to the one shown at 2:46.
Thanks for sharing. I use a home made fan dipole 80, 40, 20 all full size 1/2 wave dipoles.
You can use the metal mast as one of the elements. Make it 23 ft for example and use it as your 30 meter element . Just be sure to space the wires at least 6 inches or more away from the mast. A commercial example of this very thing is the 17 meter add on for the 4BTV.
@feltusfeicit
Жыл бұрын
I was wondering if this was not an option. I am thinking of re-jigging my antennas: 20' of chainlink fence top tube guyed with 3 lines at 10 and 20 foot using steel wire/rope. Topping this with a pulley and my Cushcraft R5, then hanging an 80m EFHW just above my 40/20/10m fan dipole. My thought is to gain 6 feet in height for the dipole, and use the guys as a ground plane for the R5. Though the instructions say to not install the R5 near a "ground radial system", I am guessing it would not suffer from having 3 sloping grounded radials: I am trying to justify using steel guys, since the Arizona sun has no respect for nylon rope, which worries me as the mast gets taller.
You cold use the metal mast AS one element of the antenna, as long is its not grounded of course. I have plans on making a DX commander like antenna this way using a harbor freight flag pole.
Would you say that a metal mast (such as a long , telescoping fishing pole) is best replaced by a fiberglass pole? When (under what circumstances) can metal masts be used? Also, are carbon fiber poles a problem because they can be conductive? Many thanks, professor!
I got completely lost at 7:20 regarding the spring or the rope with a weight. Can you clarify?
Dave, The issue with trying to get a custom (ie short) KZread channel name like you have is that KZread requires you to have at least 100 subscribers to do that. FYI.
Great topic! This answered a lot of my questions about using metal masts.
Good job explaining it Dave. It's a very good antenna.
If the aluminum mast was isolated, how would it dissipate the RF? I have considered making the metal mast itself a radiant piece of the antenna, most likely the 40-meter portion. The radial plate would have to remain isolated as well, in this arrangement.
How come the longest wire on the DXcommander does not influence the shorter wires? Could a metal mast could be considered like an extra wire in the package? A metal telescopic post of the same height as DXcommander won't be mobile or easy to work with .. but that was not the question.
@patrickbuick5459
Жыл бұрын
It does. He spent considerable time and effort figuring out the lengths when all elements are in place and influencing each other.
Great video! Some antenna systems are greatly affected by how they are deployed, like the old standby VHF j-pole antenna.
Here's a video of Stacy's setup: kzread.info/dash/bejne/l2p3prVmj8WzZ8o.html
@johnbauman4005
Жыл бұрын
Not any more. It's marked private. Thanks anyway.
I don’t think you can have short names for KZread channels until you have a minimum number of subscribers.
Does the same rule apply for receiving antenna?
A metal mast standing beside the radiating elements as it holds them up is completely different to a metal mast with an antenna sitting on the top. In fact the metal mast will assist a ground plain/counterpoise style antenna, especially if you connect it to Earth.
But if mast is metal and resonant on lower band, I think so must work, but wire element and metal mast behave different, different Z 73 de 9a3hp
Use the metal mast as part of the antenna system. This would mean shortening the existing wire elements.
Thoughts on tuning with suspended wires then converting to freestanding by replacing the longest hanging radiator with a structural metal pole?
Great video OG
Interesting explanation
Hi, Dave - you mentioned the Alpha Delta fan dipole, but didn't mention whether a metal mast would affect it. I was under the impression that a metal mast doesn't affect a horizontal/inverted-V dipole, and I have a DX-CC about 35 feet up at the center point, inverted-V, on a metal telescoping mast. It gets out pretty well but wonder if it would be better with a plastic mast. Unfortunately, we get very high winds here, and the metal mast is more stable. Thanks for your great videos! Bob, KJ6GEU
@yokiniqu
Жыл бұрын
I'm thinking of using a metal mast but perhaps the last 3ft at the top could be pvc.
ok, I have a HF radio and am using an NVIS 40-10 antenna. I plan to raise this up to 15 feet at the center. This will be done from a bed of a pickup truck. Will the pickup truck (metal) affect the overall performance of the radio?
Nice job.
Could you use a metal mast with an off center fed dipole at the feed point?
@theranger2185
2 жыл бұрын
I would love to know this as well
@Brenda-jf2pe
8 күн бұрын
@@theranger2185yes, use steel tv mast not aluminum mount the unun 16 inches away from the mast. I used a plastic cooking cutting board. Made a strip 3inches wide mounted with C clamps to mast . Works fine run coax doing mast with tape. Steel less capacitance then aluminum. Try it. KJ7TBR
While it would work, you throw out all the measurements and trial and error Callum put in to develop the DX Commander. If you want to go about the sizing all over again due to the (significant) interaction with the metal pole, then in theory it would work. Spacing would definitely be important to lower interaction.
Enjoyed your video - who is the little guy walking across the screen?
In the womans question about the metal mast. What if you ran PVC pipe over the mast as a shield. Would that help her?
@patrickbuick5459
Жыл бұрын
Does PVC block magnetic fields?
Could you use a metal mast for an inverted v antenna
@aa5df
3 жыл бұрын
Yes. I had a fan inverted vee dipole antenna suspended from a pulley atop 30 feet of metal pipe. Just keep the antenna legs no less than 45 degrees from the mast. There will be some interaction so once you get the dipoles tuned, you may find some interaction if you change the angle. The antenna worked great on 80, 40, 20, and 15 meters. I also had a 10m dipole up there as well, but didn’t use it much at the pit of the solar cycle in 1985.
@johnmullis6589
3 жыл бұрын
Cool I plan on building a 30 foot mast out of some 80sch aluminum pipe to use as a center for my fan dipole for 40 20 and 17
should i isolate my 5/8 wave from metal mast?
Could a carbon fiber mast be used for a DXC type antenna? Or is cf conductive enough to also be an issue?
@mrmomb
3 жыл бұрын
Carbon fiber is RF conductive.
@polymath5119
3 жыл бұрын
SOTAbeams has a video about this, in which he tests whether the RF conductivity of the carbon fiber mast he sells is significant enough to matter.
maybe can use a non conductive mast to hold it up thnls for vivio
What is your involvement with Meta in detail my friend?
No matter what, when you can literally work the world with a hundred watts with a combination Chameleon CHA - MIL Hybrid rated at 500 watts coupled with a Stryker A10 Trucker Mount mobile antenna because it's 5/8 wave by itself which I've found works as well as an Antron 99, it makes it all worthwhile.
@patrickbuick5459
Жыл бұрын
I tried lots of verticals on my CHA Hybrid mini on my Jeep on a Breedlove mount. MIL2.0 with EXT and cap hat, SG303, CHA V1, 102" SS whip etc. They did work reasonably well on the higher bands, but I wanted 80m local net, which they didn't. I'll try them out more on the higher bands when it is warmer out. Admittedly, my DX Commander 12.4m Signature does transmit well, down on 80m, there is too much noise in my urban environment, so I used that Hybrid with 130 feet of wire as an EFHW and cut the noise significantly. It is held up with an aluminum painters pole at the moment. I'm now in the process of doing up a control box to do T/R automatic with optional manual switching using my existing remote antenna switch. I'll likely get much further with the much taller, resonant antenna.
Why do people use chain link fence top rail for a mast?
@patrickbuick5459
Жыл бұрын
Strength
@aandpman
Жыл бұрын
Cheap, and easy to find at Lowe's/Depot
@Brenda-jf2pe
8 күн бұрын
Steel better than aluminum
Dave love your channel. Thank You. I believe Stacy is a he not a she. His beard gives it away.
??? Is this really so??? I'm not so sure.... If the 40M meter element was a 10 meter long, 1 inch diameter aluminium tube, with radials, and insulated at the bottom, it would be a great radiator... Now, if you used that as a support for the shorter band elements, and 'fanned' them from the base somewhat, how is that different from the DX commander??? I''m sure going to have a play, I don't see why it shouldn't work, as long as the mast/40 meter element isn't grounded at the base, of course...
@patrickbuick5459
Жыл бұрын
I think the biggest issue would be the sheer difference in mass and therefore magnetic affect with the metal pole. If I run out of other things to do, I could spend some of the summer setting up my 23 foot flagpole vertical and trying it. I just have a hard time imagining making those wire spacers for the other bands! A more direct comparison would be a 43 foot flagpole vertical.
She used a 4 inch not a 4 foot coupler. Cut scrap PVC pipe, it is cheaper than using a coupler.
K7AER THANKS
Can Adding a carbon fiber Mast Disrupt an Antenna?
What's with that little guy walking across the screen?
In other words if it isn’t broke don’t fix it
Stacy’s parents have a lot to answer for calling their son “Stacy”.
@patrickbuick5459
Жыл бұрын
Just like the Johnny Cash song "a man named Sue"
@thomasmaughan4798
Жыл бұрын
"Stacy’s parents have a lot to answer for " To whom do they make answer?