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Author Topic: Recommendations for a 20 or 40 meter mobile antenna?  (Read 264 times)

ONAIR

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Recommendations for a 20 or 40 meter mobile antenna?
« on: March 07, 2023, 02:29:55 PM »

  Looking for something to put on a mag mount other than a Hamstick?   
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WA3SKN

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Re: Recommendations for a 20 or 40 meter mobile antenna?
« Reply #1 on: March 07, 2023, 02:36:43 PM »

Mag mounts are are poor choice for HF frequencies.  Any other choices available?

-Mike.
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AE0Q

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Re: Recommendations for a 20 or 40 meter mobile antenna?
« Reply #2 on: March 07, 2023, 04:03:04 PM »

  Looking for something to put on a mag mount other than a Hamstick?
Use a Hustler on the (taller) 54 inch mast, the loading coil is farther up the mast than the coil on a hamstick (at the bottom).  Makes for better efficiency.
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ONAIR

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Re: Recommendations for a 20 or 40 meter mobile antenna?
« Reply #3 on: March 07, 2023, 11:13:31 PM »

Mag mounts are are poor choice for HF frequencies.  Any other choices available?

-Mike.
  Can do a trunk mount.
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ONAIR

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Re: Recommendations for a 20 or 40 meter mobile antenna?
« Reply #4 on: March 07, 2023, 11:25:11 PM »

  Looking for something to put on a mag mount other than a Hamstick?
Use a Hustler on the (taller) 54 inch mast, the loading coil is farther up the mast than the coil on a hamstick (at the bottom).  Makes for better efficiency.
   Thanks! Know anything about the Diamond mobile antennas?
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KD6VXI

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Re: Recommendations for a 20 or 40 meter mobile antenna?
« Reply #5 on: March 08, 2023, 03:03:57 AM »

Mag mounts are are poor choice for HF frequencies.  Any other choices available?

-Mike.
  Can do a trunk mount.

MUCH better option.  Trunk mounts usually dig into the metal and allow for a good connection to the ground / chassis of the vehicle.

Mag mount.....  Not so much.  They use capacitive connection to the body of the car, much more lossy.....  And that's the good ones.  The poor Mag mounts just use the shield of the coax.

A Mag mount is the answer when the question is how to keep an antenna away from DC ground.

--Shane
WP2ASS / ex KD6VXI
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K5LXP

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Re: Recommendations for a 20 or 40 meter mobile antenna?
« Reply #6 on: March 08, 2023, 05:06:51 AM »

A triple mag mount offers better coupling to the body and allows for a larger (ostensibly more efficient) antenna.  Convenience is about all a mag mount offers, pretty much everything else about the installation suffers.  Hamsticks are generally at the bottom of the antenna food chain but on 20M you can do alright with one with proper expectation.  I operate a similar efficiency-challenged HF mobile antenna and it's no pileup buster, but I have fun with it on trips.  40M is a greater challenge with low efficiency antennas but running CW I get the advantage of that mode "gain".  If you can get past the notion of a mag mount for an HF antenna, then I would say even a hamstick can do OK if the goal is to be HF mobile.  From there you can work your way up more efficient solutions if the interest is there.

Mark K5LXP
Albuquerque, NM
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KK4YDR

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Re: Recommendations for a 20 or 40 meter mobile antenna?
« Reply #7 on: March 15, 2023, 09:32:31 AM »

I think no one has answered your question directly because the word HF + mag mount = massive red flags to everyone reading and thats why its highly recommended not to mag mount. I do answer your question below but not as you expect.

I would not do a mag mount. Get an NMO mount or install a proper drilled mount. Get a professional to do it for you if you cant. If you are going to keep your car for years and years, the resale value will already be in the dumpster and drilling a hole does nothing to the resale value. I have two vehicles with NMO mounts and its been years and years and the mounts are fine, no rust, no warping, etc.... I run Scorpion Antenna, Tarheel II, and Larsen VHF/UHF whips. NMO, and other custom mounts. With the NMO I can take off the antenna with a twist and put a tiny little dust cap on it and no one can see it and if they do it looks like a modern satellite radio micro antenna with the dust cap on.

To answer your question the only antenna I can think of that is going to be a monoband other than a hamstick is a hamstick. I am sorry. antennas are all monoband. Do not use a tuner mobile they are useless. They are basically useless on big antennas as well unless your running balanced line loops and other non dipole based antennas. Remember that a tuner is a pretend good antenna. they just make a non resonant antenna look resonant to a radio but the antenna is still non resonant and grossly represents a dummy load outside of the tuner. In a car you want resonance to occur naturally in harmony with the mass under the antenna being the whole vehicle and the vehicle its-self is a massive capacitively coupled ground plane to the Earth. Mag mounts sure they work but think of your electrical connection. Your ground plane is as big as the magnets and the entire vehicle is basically ignored. There is only 1 or 2 correct ways to do mobile HF and then there is everything else which is just bad and wrong. Good luck.

What I propose as an actual solution is as follows:

Buy a drill installed 3/8-24 mount, Breedlove makes great mounts. Have it drilled and installed. Or install an NMO heavy duty mount from Breedlove or anyone else that reinforces the sheet metal from beneath. They make NMO to 3/8-24 adapters. Buy a Little Tarheel II and use that. Get a good screwdrive controller either manual or digital, MFJ, TurboTuner, West Mountain, etc... and set everything up. Bond everything in the car to its-self, i.e. door to frame, hood to frame, exhaust to frame, bumper bars to frame, etc... via 1" wide copper flexible ground strap.

Then be AMAZED at what you can work and who can hear you and you can change bands from 3.5 to 50mhz while doing 70mph down the highway never getting out of your vehicle.

or .... you can run a magmount and keep posting questions on how to get things to work better when there is no other way to make them work better besides a properly drilled mount. And even if you drill a mount for your hamstick that antenna will not truly shine until you strap bond everything in your vehicle.

Mobile HF should be completely abandoned unless you are willing to compromise heavily and modify that vehicle. Otherwise youre going to make a contact or three sure. Even coax can radiate its common model so so like an antenna. But I will be making a hundred 5/9's while your still hunting for your 3rd contact. It makes that big of a difference. And it took a long time to type all this so I do care very much for your success.
« Last Edit: March 15, 2023, 09:46:33 AM by KK4YDR »
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WS0SWV

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Re: Recommendations for a 20 or 40 meter mobile antenna?
« Reply #8 on: March 15, 2023, 09:49:57 AM »

I’ve built several dipoles and i always seem to return to my EFHW. Designed for 40/2015/10.  Tunes on everything else but 6M.  Mine is a MyAntennas.com variety for 100W use. Lots of small QRP versions o. The market.
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KK4YDR

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Re: Recommendations for a 20 or 40 meter mobile antenna?
« Reply #9 on: March 15, 2023, 10:49:40 PM »

I’ve built several dipoles and i always seem to return to my EFHW. Designed for 40/2015/10.  Tunes on everything else but 6M.  Mine is a MyAntennas.com variety for 100W use. Lots of small QRP versions o. The market.

Yeah but he cant use a dipole or end fed half wave while driving around town.
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ONAIR

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Re: Recommendations for a 20 or 40 meter mobile antenna?
« Reply #10 on: March 20, 2023, 09:05:35 PM »

I think no one has answered your question directly because the word HF + mag mount = massive red flags to everyone reading and thats why its highly recommended not to mag mount. I do answer your question below but not as you expect.

I would not do a mag mount. Get an NMO mount or install a proper drilled mount. Get a professional to do it for you if you cant. If you are going to keep your car for years and years, the resale value will already be in the dumpster and drilling a hole does nothing to the resale value. I have two vehicles with NMO mounts and its been years and years and the mounts are fine, no rust, no warping, etc.... I run Scorpion Antenna, Tarheel II, and Larsen VHF/UHF whips. NMO, and other custom mounts. With the NMO I can take off the antenna with a twist and put a tiny little dust cap on it and no one can see it and if they do it looks like a modern satellite radio micro antenna with the dust cap on.

To answer your question the only antenna I can think of that is going to be a monoband other than a hamstick is a hamstick. I am sorry. antennas are all monoband. Do not use a tuner mobile they are useless. They are basically useless on big antennas as well unless your running balanced line loops and other non dipole based antennas. Remember that a tuner is a pretend good antenna. they just make a non resonant antenna look resonant to a radio but the antenna is still non resonant and grossly represents a dummy load outside of the tuner. In a car you want resonance to occur naturally in harmony with the mass under the antenna being the whole vehicle and the vehicle its-self is a massive capacitively coupled ground plane to the Earth. Mag mounts sure they work but think of your electrical connection. Your ground plane is as big as the magnets and the entire vehicle is basically ignored. There is only 1 or 2 correct ways to do mobile HF and then there is everything else which is just bad and wrong. Good luck.

What I propose as an actual solution is as follows:

Buy a drill installed 3/8-24 mount, Breedlove makes great mounts. Have it drilled and installed. Or install an NMO heavy duty mount from Breedlove or anyone else that reinforces the sheet metal from beneath. They make NMO to 3/8-24 adapters. Buy a Little Tarheel II and use that. Get a good screwdrive controller either manual or digital, MFJ, TurboTuner, West Mountain, etc... and set everything up. Bond everything in the car to its-self, i.e. door to frame, hood to frame, exhaust to frame, bumper bars to frame, etc... via 1" wide copper flexible ground strap.

Then be AMAZED at what you can work and who can hear you and you can change bands from 3.5 to 50mhz while doing 70mph down the highway never getting out of your vehicle.

or .... you can run a magmount and keep posting questions on how to get things to work better when there is no other way to make them work better besides a properly drilled mount. And even if you drill a mount for your hamstick that antenna will not truly shine until you strap bond everything in your vehicle.

Mobile HF should be completely abandoned unless you are willing to compromise heavily and modify that vehicle. Otherwise youre going to make a contact or three sure. Even coax can radiate its common model so so like an antenna. But I will be making a hundred 5/9's while your still hunting for your 3rd contact. It makes that big of a difference. And it took a long time to type all this so I do care very much for your success.
   Thanks for the detailed response!  Will go for the screwdriver and mount.
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