• Welcome to our site! Electro Tech is an online community (with over 170,000 members) who enjoy talking about and building electronic circuits, projects and gadgets. To participate you need to register. Registration is free. Click here to register now.

How do you tell if an antenna BalUn is bad?

Status
Not open for further replies.

blueroomelectronics

Well-Known Member
I've got a pair of these UHF Yagis for HDTV, they appear identical and one picks up wonderfully, the other is about 1/2 the strength. I figure it's the BalUn but I have no idea (it's sealed but I don't mind cutting it open) how to test it.
 

kchriste

New Member
Forum Supporter
Without a network or VSWR analyzer, substitution is the only way I can think of.
 

MikeMl

Well-Known Member
Most Helpful Member
Ohm them both. If the flaky one has different dc resistances port to port than the good one, chances a winding has opened up. Google for balun to see how the windings are connected.
 

Leftyretro

New Member
"Rf is weird stuff. "

RF is weird esp at VHF and above. I'm convinced that many times a person just stumbles on something that seems to work and later comes up with the theory of why it works. :p

PS: doesn't seem like there is much to go wrong with that 'balun'. Have you tried to replace or swap the antenna leadwire/connector(s), that has been might biggest hitters on my external mounted stuff over the years, water/moisture is not good at these frequencies.

Lefty
 

Hero999

Banned
Is it still within the warranty?

If so I think, it's best to take it back to the shop and get a replacement.
 

blueroomelectronics

Well-Known Member
I should take it back, I just can't resist the hack. I would think a poor BalUn was a weak point and was hoping a $3 Radio Shack BalUn might help. I'll measure the two Yagi's tonight, see if I can spot a difference. I suspect it could be the wonky case design.

Screw, Antenna loop, plastic case, PCB, plastic case, nut.

How does it make good contact with the PCB I wonder?
 

karyoker

New Member
At that frequency you have a large cable loss in fact it there is a direct 90 degree bend in the co-ax it kills it. I would suspect corroded terminal connections. Lightning will open a balun but it can be checked with an ohm meter. A 3 DB loss could also be attributed to the termination which is probably 75 ohms.
 
Last edited:

blueroomelectronics

Well-Known Member
Really I never heard about bends in the coax causing problems but doesn't hurt to straighten it out. The antenna is new and is attic mounted so corrosion isn't a problem. My curiosity will dissassemble it tonight and bust open the glue seal.
 
Status
Not open for further replies.

Latest threads

EE World Online Articles

Loading
Top