eHam
eHam Forums => Repeaters => Topic started by: KD2E on December 04, 2019, 08:02:30 AM
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Hey guys.....Just to listen to local repeaters while at the workbench, I'd like to put something uber-simple outside. I was gonna just drop a car mag-mount on the Bilco door, but..ok...I'll go a little farther than that. I was thinking something like this.
Can you suggest any of these items?
A. Smallest, lightest commercial 2M FM antenna
B. Vent pipe to mast, simple clamp
C. Aluminum mast, only about 3 feet .
Yes, I could build a J-pole, and an aluminum plate..drill holes for ubolts to make the bracket, and a tv mast
from Lowe's cut down a bit.....but, I'd like to just order everything from some where, and spend an hour some day throwing it up...That's the plan!
....Dave
I don't want to put much leverage on those vent pipes. They feel sturdy, but I'm sure there's just a nail banged in to a beam, and bent around the vent pipe for its' construction!!!
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The Arrow Antenna J-Pole or the Comet GP-1 ground plane antenna are both small and well-built. I've used a short piece of PVC pipe with wood closet rod inside as a mast.
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It only takes a few minutes to make a ribbon cable J-Pole, also known as a Slim-Jim. Costs very little. Wind a few turns of the feeder into a coil to act as a feedline choke.
https://m0ukd.com/calculators/slim-jim-and-j-pole-calculator/
http://www.m0pzt.com/slimjim/
73 Dave
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What I would consider doing in that situation would be to get something along the lines of the Larsen BSAKIT and an NMO mount antenna such as the Larsen NMOQBLACK or NMOQC and put them together.
You would want to cut the antenna element to length and the radial elements may benefit from a trimming as well, but it would be a relatively simple and effective install and wouldn't put much additional loading/stress on your vent pipe.
I haven't personally used that particular kit and there are other companies that make similar products, but I've been satisfied with my results with other Larsen products so would probably go that direction.
There is a good chance you wouldn't need much or any mast to use it with your local repeaters, but a short piece of painted 2x4 could be used if you wanted to get it a bit higher above the vent pipe.
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Many years ago during the 80's for indoor use i had a vhf 1/2 wave hanging antenna(from a curtin rod) that worked extremely well indoors i used with either my HT or with a very small base station setup. I have looked all over the internet and can not find it or anything like it. Sure wish I still had that antenna. It consisted of a coil and radiating cable with a small loop on the end that hung on the nearest curtin rod. If i could find one i would buy it. It was either made by Larsen or possibly Hustler i just can not remember who the manufacture was.
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For a drop-ship solution, an NMO ground plane kit plus quarter wave NMO whip checks the box. That's what I'm running on the roof of my garage.
(https://images-na.ssl-images-amazon.com/images/I/51VxPuEGonL._SX425_.jpg)
Mark K5LXP
Albuquerque, NM
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For a drop-ship solution, an NMO ground plane kit plus quarter wave NMO whip checks the box. That's what I'm running on the roof of my garage.
(https://images-na.ssl-images-amazon.com/images/I/51VxPuEGonL._SX425_.jpg)
Mark K5LXP
Albuquerque, NM
Yep, that's exactly the type of setup I was referring to.
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There are any number of inexpensive ground plane antennas designed for scanners, etc.
that will work just fine on 2m, even for transmitting at reasonable power levels, that will
be cheaper than buying an NMO base, whip, and radial kit.
(Those who wish can make one quite easily, of course.)
Most have a coax connector coming out the bottom. This actually makes for an easy
installation:
My vent pipes are standard ABS pipe, but you can do this with other types as well.
Get a "Y" fitting that looks like this that fits on the top of your vent:
(https://images.homedepot-static.com/productImages/46cad34f-c275-4d51-882a-8f8e465805ac/svn/black-nibco-abs-fittings-c5810hd22112-64_400_compressed.jpg)
Stick it on top of the vent pipe with the angled leg going down to one side. Stick the coax
up from the bottom of the angled leg and out the top, and attach it to the ground plane.
Then just set the ground plane on top of the fitting - if you want to get fancy you can bend
the radials so they run horizontally to the edge of the pipe then angle downwards.
And... that's it. The weight of the coax holds the antenna in place (you can secure the
coax to the vent pipe if you need more retention strength.
If you want it higher, just use an extension of ABS pipe and a coupler between the top of
the vent and the Y fitting.
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And using the above "Y" fitting if you want to save money on the antenna you can make a 1/4 wave 2 meter vertical very easily and on the cheap. Get an SO239 chassis connector. Solder a 19 inch copper wire or for more stiffness a piece of brass welding rod to the center pin and make 4 "radials" of the same length bent downward at about 45 degrees. Plug in your coax thru the "Y" and weatherrpoof that connection. The 1/4 wave antenna can sit on the "Y" top or if need be you could cut 4 slots in the top of it for the radials to set in. Paint the whole thing the color of your roof, and you wouldn't even see it 10 foot away.
Total economic outlay would be very little, and just a small amount of work.
For a really stealthy install, If in the attic you can get you hands on the vent pipe you can drill a small hole in the side of the vent pipe and fish up the coax inside the vent pipe to the top. Be sure to seal the hole with waterproof sealant and a small drip loop inside the pipe would be a good idea too. You don't want rainwater coming down and following the coax out into the attic space. Rainwater coming down into the pipe into the sewer drain is fine, but not coming out into the hole you drilled into the pipe.
In this manner no coax is showing on the outside of the pipe, No "Y" adaptor needed, Just paint the antenna and pipe on the outside the same color as your roof and it will blend in.
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If you have access to the attic, just hang it there where it is out of the weather rather than
trying to get up on the roof (especially if you don't want to attract attention).
I couldn't get into the part of my attic where I wanted to install my 2m antenna, so I just
drilled a hole in the ceiling right inside the door of a closet, stuck an antenna in a piece of
pipe up through the insulation, and secured it to the wall over the door with a conduit clamp.
Can't see it at all unless you walk into the closet, turn around, and look up over the inside
of the door, and it works just fine. With a ground plane you can stick the radiator up through
a small hole and run the radials across the closet ceiling.
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If you have access to the attic, just hang it there where it is out of the weather rather than
trying to get up on the roof (especially if you don't want to attract attention).
I couldn't get into the part of my attic where I wanted to install my 2m antenna, so I just
drilled a hole in the ceiling right inside the door of a closet, stuck an antenna in a piece of
pipe up through the insulation, and secured it to the wall over the door with a conduit clamp.
Can't see it at all unless you walk into the closet, turn around, and look up over the inside
of the door, and it works just fine. With a ground plane you can stick the radiator up through
a small hole and run the radials across the closet ceiling.
Pretty stealthy. :)
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Many years ago during the 80's for indoor use i had a vhf 1/2 wave hanging antenna(from a curtin rod) that worked extremely well indoors i used with either my HT or with a very small base station setup. I have looked all over the internet and can not find it or anything like it. Sure wish I still had that antenna. It consisted of a coil and radiating cable with a small loop on the end that hung on the nearest curtin rod. If i could find one i would buy it. It was either made by Larsen or possibly Hustler i just can not remember who the manufacture was.
Well - found it but its not 1/2 wave like I thought it was. I's a 5/8 wave antenna - see below
https://www.gigaparts.com/larsen-phw-150c-5-8-wave-ant-super-flex-whip-black-base-stainless-steel-whip.html
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The Arrow Antenna J-Pole or the Comet GP-1 ground plane antenna are both small and well-built. I've used a short piece of PVC pipe with wood closet rod inside as a mast.
I've purchased both those antennas. I still own the Comet GP-1 and it's served me well.
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simple and cheap
https://n9taxlabs.com/
73 wt1v
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Consider the Comet B-10. It's only 11.5 inches long.
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2019 post. He might have built something by now.
-Mike.
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2019 post.
-Mike.