Help a newb build a Yagi

[W4LKR]

After watching Moleculo's how-to video on working AO-51 with a handheld I'd like to build a Yagi for 2m/70cm satellite work. I'm new to antennas, but not to techy DIY projects in general.

I've already figured out how to program my FT-60R to TX/RX split band. Being new to ham radio in general I'm not clear on whether I need a duplexer built onto the Yagi. Arrow and others sell them this way, but isn't my FT-60R already taking care of it as-is? In other words, all I want to do is replace the stock antenna with a Yagi. So if it works as-is, shouldn't it work with the Yagi connected instead of the rubber duck?

Thanks!

 

[W4LKR]

Disregard my previous question, further reading cleared it up.

Building a 2m/70cm Yagi seems pretty straightforward. I am having trouble sourcing a device to mount on the antenna that will detect when the radio transmits and switches between the two antennas as appropriate.

 

[AudioShockwav]

I am having trouble sourcing a device to mount on the antenna that will detect when the radio transmits and switches between the two antennas as appropriate.

You need a 2 meter/440 duplexer
Have a look here:

NCG Company::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::
The Arrow Hand held Antenna has a duplexer built into the handle.
One coax to the radio into the duplexer, and two connectors out of the duplexer, one to your 2 meter antenna, and one to your 440 antenna, there is no "switching " it uses band pass filters inside the duplexer to split the signal.

Duplexers
Duplexer/Splitter/Combiner

Comet calls these "duplexers", but they are also referred to as combiners or splitters. They are basically band-pass filters, simultaneously passing RF in both directions through the common connector while the band-pass filters provide a high degree of isolation between ports.
* TX and RX from two radios at the same time into a dual-band antenna

* Combine a dual-band radio with separate outputs into a dual-band antenna

* Separate a single connector duplexed radio into separate antenna systems

* Allow a single coax run into two antennas at the top of the tower, and two radios at the bottom by using a duplexer at both ends of the coax run, avoiding cost and weight.

73
Jeff

 

[W4LKR]

Thanks Jeff, I appreciate the clarification and link for the duplexers. I also found this which looks like a good and cheaper option:

2m/440 duplexer on ebay

I'm thinking of soldering it inside a project box from Radio Shack and adding coax connectors.

The PDF guide to building inexpensive Yagi antennas recommends copper tubing for the driven element. I can get plenty of it fairly cheaply from onlinemetals.com. Is it okay to use the same material for the reflector and directors? Or is it better to use a different metal?

Thanks for your help!

 

[AudioShockwav]

The copper should work just fine as long as it is stiff enough to hold it`s shape


73
Jeff.

 

[W4LKR]

I'm wondering if either of these would be okay for the driven element, directors and reflectors? I found 1/4" copper tube and also some 9 gauge steel wire at Lowe's. Economical, but how difficult would it be to straighten it? Do they need to be perfectly straight?

 

[AudioShockwav]

I have used 1/4 inch tubing just like that for a 2 meter yagi i had built several years ago.....i used it for all of the elements because it was what i had on hand at the time and it worked just fine.
It is easy to work with.


73
Jeff

 

[W4LKR]

I have used 1/4 inch tubing just like that for a 2 meter yagi i had built several years ago.....i used it for all of the elements because it was what i had on hand at the time and it worked just fine.
It is easy to work with.


73
Jeff

How did you straighten it? Maybe that's a dumb question, I just mean did you bend it by hand and eyeball it, or did you make up a jig or was there a trick to it? I assume it does not have to be as perfectly straight as a prefab copper pipe.

 

[AudioShockwav]

Yes i just bent it by hand, it is fairly soft and did not take much effort, it is easy to work with.
I was not using it for a hand held antenna so i did not worry about it getting bent while in use.
Now that I think about it that is probably the advantage to the Arrow antenna that uses shaft`s for the elements as they are sturdy in use.
I think Lowes/HD sells hard copper tube in straight lengths that might be more suitable for what you are thinking about as the rolled stuff is fairly soft.


73
jeff

 

[W4LKR]

Thanks that's a good point. Now I'm leaning towards ordering some 3/16" aluminum rod or tube from onlinemetals.com for all elements.

Another question popped up after I watched some how-to videos on building more substantial yagis for permanent setups. The resonance of the feedline is emphasized, and yet I see very short feedlines for connecting handheld yagis to handheld radios. Is resonance less important when connecting an external antenna to a handheld? I ask because one example video has something like 20 feet of coax because that length was resonant at 2m. But again, all the handheld yagis I've seen connected to handheld radios have very short feedlines, like two or three feet.

Thanks for sticking with my thread. This has been very helpful!

 

[Kiev88CM]

This may be too late but tubing bender at Home Depot. Copper tubing is annealed to be soft and flexible but , once you're done with your bends heat it and let it slowly cool and it will get hard.

 

[WA8ZYT]

I get all my aluminum tubing for antenna elements from DX Engineering.

They have all kinds of stuff for constructing antennas. Prices and shipping are very reasonable.