Hey,

well i setup the antenna and I tried to make a balun for it. I do not get a signal.

A couple pictures below.

Please point me to a store bought 4:1 balun, or the proper way to build one for this antenna.

thanks

http://www.digitalhome.ca/forum/picture.php?albumid=269&pictureid=1218

http://www.digitalhome.ca/forum/picture.php?albumid=269&pictureid=1219

well i setup the antenna and I tried to make a balun for it. I do not get a signal.

A couple pictures below.
Do you perhaps know a friend who is good at photography? If so, then get them to photograph the balun and the antenna for us, and post fresh photos that actually show the necessary detail.

Then we can help.

Yes, closer pictures please, but from what I can see, the connections are not good. It looks like your feed wire goes to the center pole and the ground connections are way too far apart. With a but of re-work, I am sure you can get them fixed up though.

Yes, closer pictures please, but from what I can see, the connections are not good. It looks like your feed wire goes to the center pole and the ground connections are way too far apart. With a but of re-work, I am sure you can get them fixed up though.
Hey,

thanks for the reply.

Sorry about the bad pictures, I will take some better ones tonight.

I connected the cables right beside the original spot as they was a rivet there, and yes my feed wire goes to the center pole.

Where would be the best place to put my feed wire?

thanks

Hey,

I hope you can see these pictures better.

thanks for the help.

Old balun inside.

http://www.digitalhome.ca/forum/picture.php?albumid=269&pictureid=1225

old balun outside

http://www.digitalhome.ca/forum/picture.php?albumid=269&pictureid=1224

new connection beside old connection rivet

http://www.digitalhome.ca/forum/picture.php?albumid=269&pictureid=1222

side view of homemade balun (attempt)

http://www.digitalhome.ca/forum/picture.php?albumid=269&pictureid=1223

That's a BALUN????

You must not have a MACRO selection on your camera (cellphone?).

Try again, this time go outside for more light and shoot from at least 3-ft away
and perhaps also from 6-ft away at wide angle, normal and moderate tele settings
until you determine what works best. I also enable FORCE FLASH, but must
shoot from an angle to avoid reflecting the flash directly back at the camera.

You'll have more than enough resolution for posting after cropping.

Looks like ballanced RLC network. I count 4 resistors (2 x 470k + 2 x ?), a couple of caps and a couple of inductors

It looks like an old diplexer for VHF-hi and VHF-low.

What you see in the pic is what I see. It is very dirty. I hooked up to original connections and I get the best reception on channel 9.

I would prefer something new, but have been unable to find a 4:1 balun.

Other option would be using the reflectors on my sbgh as narods to see if I can improve the VHF signals on that antenna, as it does have better reception than the old Delhi seen in the pictures.

Thanks for your help.

Edit.

I took another shot at some pictures, this time outside, rather than my dark basement..

I am not sure if it even is a balun, it had four connections, so i figured it was a 4:1 balun.

I disconnected from antenna and I actually get better reception without it connected to the antenna.

All photos can be viewed here. http://photoshare.shaw.ca/messages/viewshow/11639258356-1247949712-55973/parm/page/

To big to upload to site.

thanks

I broke the 300 ohms twin lead cable on my homemade balun.

I went to Addison to get some cheap combiners with a 300 ohms lead and I got a log one (6 inches) on an old combiner. I had a 2 inches twin lead before.

Soldered back on my balun and my results are not the same anymore.

Is it because the twin-lead was too long?

I will work on this Tomorrow at work. Maybe I will just do what MLord does; wrap the coax loop under the boom of the antenna with no plastic box.

Intravino

What you see in the pic is what I see. It is very dirty.
That's not a balun. It appears to be a small (out-of-focus) circuit for combining UHF/VHF into a single 300-ohm twinlead connection. Also known as a "UVSJ" (UHF/VHF Splitter/Joiner).

You probably used twinlead with this antenna before (right?), connecting it to the two small brass screws shown in one of those photos.

If not, then that's your problem. This antenna does not accept a direct coax connection.. even with that little black box it still requires you to add a (store-bought) balun (or "matching transformer") to it.

Best bet is to reinstall the box, and use a single 4:1 balun at the screw terminals to convert it for coax (RG6), and go from there.

Cheers

I broke the 300 ohms twin lead cable on my homemade balun.

I went to Addison to get some cheap combiners with a 300 ohms lead and I got a log one (6 inches) on an old combiner. I had a 2 inches twin lead before.

Soldered back on my balun and my results are not the same anymore.

Is it because the twin-lead was too long?

Dunno. The ideal length for that piece of twinlead, measured *after* hooking it up at each end, is 1/4 wavelength (half the length of your coax loop). Or any nice even half multiple of that (I think).

Changing the length of it will affect things, sometimes good, sometimes bad.

Would you like me to mail you some twinlead ? :)

Cheers

This antenna does not accept a direct coax connection.. even with that little black box it still requires you to add a (store-bought) balun (or "matching transformer") to it.

Best bet is to reinstall the box, and use a single 4:1 balun at the screw terminals to convert it for coax (RG6), and go from there.
Or, failing that, you could use separate baluns on each half of the antenna, and combine them together with a store-bought UVSJ coupler (not an ordinary splitter).

...The ideal length for that piece of twinlead, measured *after* hooking it up at each end, is 1/4 wavelength (half the length of your coax loop)...

Man, my ignorance is showing:eek: I had no idea the length of twinlead mattered for the homemade balun, just thought it was the coax length that mattered. I must have gotten lucky with my first one as I wasn't able to repeat the same results for my next two channel specific baluns. My biologist background doesn't appear to help matters much...:rolleyes:

So to get it straight ... it goes individual (separated) leads of the twinlead connected to the feedpoints, joined twinlead section (1/4 wavelength (or half multiples) section), connection to balun leads (short coax stubs)?

So to get it straight ... it goes individual (separated) leads of the twinlead connected to the feedpoints, joined twinlead section (1/4 wavelength (or half multiples) section), connection to balun leads (short coax stubs)?
Yeah, assuming the "short individual leads" are running at right angles from the twinlead out to the feedpoint screw terminals.

I think. :)

The idea, is that a 1/4 wavelength section of wire is a nice balun for matching two different impedances. Ideally, the wire used would be the average of the input/ouput impedances. In this case, the in/out are theoretically both 300ohm, but probably different in practice.

If you think about how it works, any signal reflections that occur (due to impedance mismatches) will happen at the joints. With a 1/4W section of wire between the joints, the reflections will line up and reinforce each other, rather than cancelling each other out.

That's the theory. In practice, I think it's best to simply not have any twinlead in there at all, but this is not always possible.

And whatever works, is all that really matters. :)

Oh, and keep whatever twinlead you do have, far far away from any metal.

Hey,

thanks for the suggestion. I get by far the best reception with that setup.

I used two baluns and connected to the uhf/vhf combiner/splitter.

I will raise the antenna and see how good it gets.

Would you like me to mail you some twinlead ?

Thanks MLord but I have a roll at work of foam type twin lead from The Source CC. I think I paid $ 1,50 for 25 feet on liquidation.

The roll is at work and I was too lazy to drive there.

The foam type is a PITA to strip.


Intravino

I am considering making a balun.

Does anyone know if it's feasable for a 4 bay bow-tie style antenna. I read thru the posts here and have not seen anyone who has used this on such an antenna.

From what I read they must be contained within an insulated box, and the coax conductors (uninsulated portion at least) must be as short as possible thus brought very close to the feedpoint.

I am concerned that with phase line gap and standoff geometry of the bow-tie, it may not lend itself to the effecient installation and placement of such a coax loop balun?

Balm,

You don't need a box, MLORD justs taped his on the boom on the antenna.

For the rest, maybe someone can answer you better !


Intravino

Balm, the home made Balun should be fine for your 4-bay and they ARE pretty simple yet effective things (thx mlord...). I've attached a couple pics of some of the ones I've made, and, as you can see, mine aren't that pretty, but they work great.

http://www.digitalhome.ca/forum/picture.php?albumid=248&pictureid=1234

http://www.digitalhome.ca/forum/picture.php?albumid=248&pictureid=1233

You can extend the feeds with twinlead in quarter wavelength multiples (see earlier post in this thread) to attach to your feedpoint. Once I find the most effective one (channel specific) for my area, I will make one a little cleaner and more permanent so that it's a little more durable and weatherproof.

Give it a try - they're pretty fun...