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How would you do this?

Robb

Robb

Honorary Member Silent Key
Dec 18, 2008
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3,654
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Silicon Valley CA, Storm Lake IA
I want to make a 2m/440 base antenna with some materials that I have laying about. I thought it would be interesting to see what any of you would use to make a usable antenna out of the following materials.

Tuning it with ? meter to assure SWR is correct?

Let's see how how resourceful you can be.
Take a shot at it.
If you've done this before, so much the better.
Remember to include that fact in your brief!

Materials that I have to use:
*An old 1/2 wave Radio Shack ground plane antenna that has a burned out matching coil.
*Two Wilson 4 ft 'Silver Loads'
*Hustler 5 ft fiberglass truck whip
*A 3 ft fiberglass whip (?)
*one angled mounting bracket w/239 connector on it and threaded portion that will accept all of the above fiberglass whips.

Radio is a Yaesu FT-8800R, power supply is a Vista XX (20 amp), and 30 ft piece of mew LMR-240 coax.

Should it have ground planes on it? How many? How long? How much masting would be optimal? etc, etc...

No J-poles; must use above materials!

Let's see what YOU would do...
;)
 
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First of it all you need good swr meter for those bands or antenna analyser.
Waste of time without that.
If you need translation, that's no problem. :)
Mike
 
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That is some nice work, I really appreciate that.

I was hoping for someone to do a 'McGyver' here and use those things on the list.
The radio, power supply, and the coax are already there to finish whatever gven antenna is put in place. Using the antenna parts that are there, how would you fashion an antenna that could be tuned with an SWR meter on 2 meters so that it would work.
That is a challenge...

PS - rubber bands, paper clips, and chewing gum aren't part of this scheme.
I also have a 10 ft mast and hardware to mount it.
So, the antenna is the ONLY thing that is lacking.
 
I'd take the SO-239. Strip five pieces of wire out of the coax, each about 20" long (and assuming this is solid wire.)

Attach one piece of the wire to the solder terminal on the connector. Attach the other four pieces, radial-style, to the four corners of the connector.

Attach the rest of the coax to the connector. Hoist it up as high as you can and have a ball.

If you simply MUST check SWR, feel free. I've made dozens of these for new hams, and helped the new hams make them for themselves. We use #12 Formvar-insulated copper wire instead of hacking up good coax, though ;) .

This is 1/4 wavelength on 2M and 3/4 wavelength on 440.

If you make the center wire about an inch longer, you can put a loop in it at the tip and use that to support the whole antenna.
 
As stated in your original post, I can't offer any easy/convenient solution. I would find that one, or several of the solutions offered that don't fit your limitations would be much easier for me.
If done correctly, I think one of your helically wound antennas could be modified (following one of those 'other' options guide lines) to produce what you are looking for. It would mean some fairly 'heavy' modifications though. Such as stripping most of the wire from that antenna, and putting it back in a different way/form. If that's 'do-able' for you, then have at it, it should work. Naturally, you'd have to furnish the 'other half' of that antenna that the car usually provides.
Another thingy that's been said here is that without the proper instruments to do the measuring/testing, don't even bother. I've found that one of those antenna analyzers is really, really handy for doing that stuff! Makes things MUCH easier/simpler. 'Course, they ain't cheap. But if you plan to any amount of this sort of stuff, it's probably the best investment you could ever make.
- 'Doc
 
Beetle said:
I'd take the SO-239. Strip five pieces of wire out of the coax, each about 20" long (and assuming this is solid wire.)

Attach one piece of the wire to the solder terminal on the connector. Attach the other four pieces, radial-style, to the four corners of the connector.

Attach the rest of the coax to the connector. Hoist it up as high as you can and have a ball.

If you simply MUST check SWR, feel free. I've made dozens of these for new hams, and helped the new hams make them for themselves. We use #12 Formvar-insulated copper wire instead of hacking up good coax, though ;) .

This is 1/4 wavelength on 2M and 3/4 wavelength on 440.

If you make the center wire about an inch longer, you can put a loop in it at the tip and use that to support the whole antenna.
Click to expand...

I use hanger wire. Just stand it up on your desk.
Rich
 
I use a Workman cross needle meter. Works great! Model SX-144/430.

It's supposed to work from 120 to 500MHz, but is more specific for 2 meter/70 cm bands...I've read some complaing that it is not very accurate on 1.25 meter.
 
n8fgb said:
I use hanger wire. Just stand it up on your desk.
Rich
Click to expand...

Yep, that works too! Just be careful doing the soldering. Wire hangers don't all use the same kind of metal. Some solders well, but others don't. Another point, if somebody's going to try this, is to scrape the wire where you'll be soldering to remove any paint, oxidation or other schmutz. Just an inch or so; might make the difference between a good connection and no connection.

And play around with the angle of the radials. This will have quite a noticeable effect on the feedpoint impedance and therefore the SWR.
 
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I broke down after failure to launch this project - and went out and bought a new Diamond X50A 2m/440 antenna. Bought it at Ham Radio Outlet for $109/tax incl. I'm going to use the 30 ft of LMR-240 I have to wire it up. I have a 10 ft mast that I'm going to mount on a 8 ft flat roof. I sold a mic and a K-40 antenna -as well as two large sacks worth of recycled soda can money - to buy it. Yeah, I'm cheap! I don't need to buy a meter now - as it is factory pre-adjusted for minimum SWR.

So, I will write it all up tomorrow when I mount it and run the radio and antenna for a test run...
 
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My 2m station is up and running. And well - I might add. The LMR-240 coax is OK for 2m; but I will need to get some LMR-400 to operate it on 70cm/440mhz. Otherwise, the db loss will be unacceptable on that freq - as I see it.

Mounted the Diamond X50A on a 10 ft mast and attached it to the side of my 8 ft flat garage roof. The repeater that I use -some 5 miles away ('N6NFI')- has me at 5-7 S-units. On simplex at the same distance I do as well. Putting it up 30 ft or so may be the way to go here. So - at some point down the line when I get better coax - I will also be sure to get a longer length and some more masting.
 
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N6NFI has some long reach. I've been able to work that repeater from Gilroy with an HT on a hill, and a good antenna.

At 5 miles you should be having a strawberry milkshake!
 
The code is "699".
I have my Diamond X50A on the top of a 10 ft mast right now. It isn't mounted to the building as yet. I may just go ahead and get the LMR-400 before I permanently mount it on the building. But for now - it works well enough to get on the VHF freq.

BTW - give me a call on N6NFI and ask me how 'Roy' is doing. I can tell you there.
...73
 

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