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Author Topic: Hygain BN-86 Balun  (Read 7359 times)
VK1OD
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Posts: 1697




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« on: February 12, 2009, 07:42:54 PM »


It is probably a 1:1 voltage balun that is really two back to back 4:1 Ruthroff baluns sharing a common winding and common magnetic circuit.

The configuration provides DC continuity between all terminals.

Why are you testing it with a DC ohmmeter?

Owen
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AI7RR
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Posts: 164




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« Reply #1 on: February 12, 2009, 07:10:01 PM »

Before I tear this thing apart, does anyone know the circuit equivalent of this balun. I just bought it used and measure shorts between the SO239 center conductor, shield and both element connectors.

Wasn't able to find the exact schematic by Googling.

Thanks,

73,, Roger
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KC8VWM
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Posts: 3121




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« Reply #2 on: February 12, 2009, 11:15:05 PM »

A balun will usually show up on a VOM meter as a short circuit.

That is normal.

73 de Charles - KC8VWM
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WA3SKN
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Posts: 5555




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« Reply #3 on: February 13, 2009, 04:21:22 AM »

Most baluns today are a either 1:1 or 4:1 current or voltage, with a toroid core.  These should test as DC shorts on the center condutor with a VOM.  So, this is good.  Testing them at the RF level they are designed for would me more of a problem.
So, what are you trying to do?  Are you having problems with your antenna system?

-Mike.
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K0BG
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Posts: 9896


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« Reply #4 on: February 13, 2009, 05:51:40 AM »

Owen is correct, and if it were mine, I'd just replace it with a new current balun, either new or home brewed.

Besides the fact they're a voltage balun, the internal connections rust. Adding some insult, bugs and spiders crawl in, allowing moisture to stick around, and eventually the enamel comes off the tri-filer windings with predictable results. Been there, done that, as they say.

Alan, KØBG
www.k0bg.com
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K9PU
Member

Posts: 67




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« Reply #5 on: February 13, 2009, 10:41:51 AM »

Take it apart, make a schematic, note how it is wound.  I bought one that was open, had to take it apart to fix, just an open air core wound on PVC pipe with a cold solder joint on the coaxial connector.    Easy to re-assemble (I bought new PVC) plus you learn what's inside.  Mine was a 1:1 balun, easy to make, now I don't buy them, I know how to make them.  

Scott
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K9PU
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Posts: 67




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« Reply #6 on: February 13, 2009, 12:34:16 PM »

P.S.

My 1:1 balun schematic shows no short across the input coax.  References indicate that there are several 1:1 baluns that do show a dc short across the input/output so you could have one of those.  You might call the vendor and ask what type it is.  Typically this could be useful for lightning protection.  Otherwise, you can test it with low power, a dummy load, and an SWR meter, assuming your transmitter is protected against short circuit connection (should your balun be faulty).  Baluns can fail from high SWR conditions, typically a short or broken core, your balun would have been really abused to fail.  

Scott
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AI7RR
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Posts: 164




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« Reply #7 on: February 13, 2009, 01:49:16 PM »

Why did I check it with a DC Ohm meter? To make sure it wasn't open. And it's not.

Okay, so far nobody has seen the inside of a BN-86. Well, now, I have. 3 coils of about 5 turns each, in what looks to be a pi configuration, wrapped on a 1/2"x3" ferrite rod.

I bought the thing very used, very cheap, to put on my TH6Dxx. Lucky for me it had been opened once before, so breaking the seal was easy.

Two potential problems I found and fixed right away: 1) the end of one coil was attached to the SO239 with a small metal (rusty) rivet. Replaced the rivet with a very small stainless nut and bolt and soldered the wire lug to the SO239.
2) cold solder joint at the center conductor. Easy fix.

Coated the whole thing with a non-conductive rubber coating.

After testing it with an rf sig gen and service monitor, other than being a little lossy, it appears to work as designed.




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K0BG
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« Reply #8 on: February 14, 2009, 11:03:06 AM »

The BN86 is a run-of-the-mill voltage balun. If you would have read my previous post, you would have noted the TRI-FILER comment.

What ever you do, don't use another voltage balun. Yes, it will work, but you're much better off with a current balun.

If you do a search on this forum, or on Google, you'll get more info than you can read in a year!


Alan, KØBG
www.k0bg.com
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AI7RR
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Posts: 164




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« Reply #9 on: February 14, 2009, 09:45:22 PM »

Alan,
Thanks for the feedback. I read your statement regarding tri-filar, but that in itself didn't answer my query about the balun's circuit equivalency.
I also checked this forum and Google but didn't find the answer I was looking for until I opened the balun myself.

I understand there is significant theory regarding baluns, voltage and current and all the variations. Hygain recommends this particular one for my application and right now I don't have any reason not to trust it will work as designed.

73,, Roger
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HB9BCZ
Member

Posts: 1




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« Reply #10 on: April 06, 2009, 02:28:40 PM »

I have opened the plastic case. As others already stated it's a voltage balun. There are 3 (trifilar) windings (W1, W2 and W3) connected in series. W1(start) = coax inner conductor, W1(end)+W2(start) = balanced out, W2(end)+W3(start) = coax ground, W3(end) = balanced out.
Measured inductivity on both ports is about 10.4uH each.
I hope this info will be useful for you.
73, Robert.
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WA1RNE
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Posts: 833




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« Reply #11 on: April 06, 2009, 05:28:18 PM »


 VE7AVV opened one up that was 25 years old.


 http://www.bcdxc.org/images/bn86_detail.JPG


 


 
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K6ZL
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Posts: 34




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« Reply #12 on: March 13, 2010, 04:03:04 AM »

Check this out;

http://www.hy-gain.com/man/pdf/BN-86.pdf
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