70cm Helical.

[KC8JPZ]

Here is the latest work in progress. Started it last night and should have it ready for testing this afternoon. It is a 8 turn Helical for 70 centimeters. The plans are from the ARRL Antenna Book. I went about the build slightly different than what the book says. They used wood for the boom and pegs that support the element. I used all PVC in my construction. Any how, here are a few pics of the main boom with the coil sized and mounted. Still have to build the feed and reflector.

 

[acarsnut]

Hey that is sweet.I love building yagi's.So this would be something new to build.would be nice to have full details for us antenna builders to try also.Looking great so far.Will keep track of this thread to see the out come.

 

[KC8JPZ]

Thanks acarsnut, a friend of mine is documenting the entire build with photos and all that. I will post specs and more pictures as soon as possible. I'm just waiting for him to get back over here to finish it up. I just finished building the mount for it. I plan on using it as a portable type setup so there isnt any rotors for control on this unit..yet. Maybe tonight we might make an attempt at a sat contact.

More to come.

 

[JnglMassiv]

Very cool looking! I can't wait for the performance report and finished photos.

 

[KC8JPZ]

UPDATE:
Putting the finishing touches on the reflector and getting ready to finish the feed.

More to come a bit later.

 

[acarsnut]

Ok been long enough. where are the updates on this sweet antenna?????

Did it work out or what.full build details please.

 

[iMONITOR]

My homeowners association would be calling Homeland Security if I put that up on my roof!

 

[k9rzz]

Sweet. How are you going to aim it?

John K9RZZ

 

[KC8JPZ]

Ok guys, I admit I have been slacking a bit on the update. It is complete now and seems to be working very well. The night we finished it up we drug it all out in the street and hooked it up to my friends TS2000 and tried to work AO-51. We had no problems at all receiving the bird. The helical received great. Our problem was the transmit antenna.My old Moxon had seen better days.. I think we need to build the 2 meter version next. (Big Antenna!)

I can't really see mounting these in a permanent fasion. We have been using this one in a more portable way. I have an old base off of a giant umbrella for the yard that I use. A few fence fiitings and a counter balance and it is quite easy to aim and spin around. We are getting read to start an elevation control project soon. I have no idea how we might hook the 2 meter helical on there. My method is to build it and I will surely find a way to mount it. There is allot of fun in these projects. Figuring out the problems is part of it for myself.

Anyhow, I'm working on a field strength meter at the moment and should be able to do some more testing with the helical this afternoon.I guess the finished project picture really isn't much better than the ones I've already posted but, here it is. I'm trying to remember where my friends pictures are posted. He has the action shots.

 

[K0ATC]

Very nice antenna, I built one for 1.3gig, Inmarsat. I put my sat antennas on a Yaesu G-5500 sat rotator, but your antenna is pretty big. You know, one thing you can do is use a metal center boom, and then non-conductive standoff’s, it will not affect the antenna, and will make it more ridged so you can support it from the end rather then the center. I imagine it flexes quite a bit if held from the end, or maybe even from the center. What is the length of the boom? Another way to get rid of flex is to slide a wood dowel into the boom. Great job, let us know when you make your first QSO, consider a yagi for the uplink, AO-51 has good ears, 3 elements would work fine.

Scott

 

[KC8JPZ]

The length of the boom is roughly 4 and a half feet from the reflector. It really does'nt flex all that much. Not enough to make any real problem. I thought about adding a dowel down the center then realized it wouldn't make it very far withthe supports going through the boom. I think if I just shove one in the boom on the reflector end that would make it allot more rigid. Anyways, it is a nice day today and I wanted to try out my field strength meter and get a feel for the pattern of this helix. It seems pretty broad from what I can tell. Here are a couple more pics of it setup on the temporary mount. Might even look for a pass today.