Because the elasticity of the conductor material and the polyethylene is quite different
Thats an older paper I guess. The RG6 Ive been using has the foamy core and Im not sure if its technically polyethylene anymore. But that may make it migrate even more, heh.

There was a line of braided-core RG6 a long time ago that allowed tight bend radii, but I don't remember the brand and I had doubts about its longevity. Times Microwave is using a solid core.

Hi,

question #1 Can a 4:1 current balun be exchanged with a common 4:1 voltage balun (would that not work with typical antennas like DB4, SBGH, folder dipole?)


question #2 I can't find the schematics on the web that would be matching the wiring I see in two common 4:1 baluns I openeds, and I paid attention to the core winding directions too. I actually destroyed it on purpose in the process of making sure I took the wiring right. Meanwhile, in the wiring I see, there is a 4th coil which is surprisingly shorted. I would appreciate if someone open a balun and confirm/link a schematic. If you can also explain how the magnetic fields flow in the usual binocular ferrite core in them, that may help a bit too.


question #3 Now, I'm still trying to find a 1:1 balun for a DIY project about making a clearstream c2 clone(2 parallel 160 ohms loop antennas is 80 ohms, requiring a 1:1 balun to 75ohms coax). For this balun, Would I need a current or a voltage one?


question #4 It looks like I won't find a 1:1 balun in common stores. For the moment I would have to recuperate the the binocular ferrite core of my destroyed balun and make a 1:1 balun myself once I get the plans... Schematic anyone?

Thanks.

Earlier today, I cited references answering these same questions in a parallel dimension:
http://www.avsforum.com/avs-vb/showthread.php?p=15679199

I think the Winegard CB-2130 (VHF only, comes with YA-1713) and CB-8269 (VHF/UHF)
are 1:1 Baluns:
http://search.solidsignal.com/?q=winegard+terminal+board&I1.x=0&I1.y=0&site=com&new_search=1

I have looked at all links and pdf, twice now (I know how to use google too ;) ). There is no association of any given circuit to the common 4:1 voltage balun we see. Meanwhile they don't answer my questions regarding whether or not the current and voltage balun are interchangeable, and which 1:1 balun I should use for a double loop antenna. At this point I would like a human answer, rather than digging endlessly tons of doc. That's why I came to the forum last :D

For receiving, current and voltage baluns are pretty much interchangable. For large mismatches or Rf fields the current balun is preferred.

Phillip Lee has cooked up a very low loss 300:75 balun (no idea of what the price point is):

http://www.tinlee.com/MATV_headend.php (scroll down to the MT-37X)

Thru loss .75 dB VHF, 1.25 dB UHF max
Return loss > 16 dB
How does its return loss compare to typical baluns?
has anyone actually used one of these, and if so can they verify that it's better (in the sense of lower losses) than the channel master baluns ?
it would be for use with a CM4228

If you're interested primarily in UHF, then a very simple coax-loop 4:1 balun costs only a buck or two to construct, and will show about 0.5dB insertion loss across much of the the UHF television band.

That kind of proposition is hard to beat!

Speaking of which.. can any of you hams enlighten me further on the gamma match feed for a dipole? To me, it looks very much like a 1/2 wavelength loop balun in disguise. :)

Cheers
ah, I once tried to make one of these, and couldn't get it to work properly (in the sense that it was very lossy). Someone I know tried as well with similar experiences

Anyone make these commercially ?

I once tried to make one of these, and couldn't get it to work properly
Weird. These things are extremely simple to make (http://rtr.ca/yagi_antennas/index.cgi?z0205655+medium), and very tolerant of small measurement errors. I wonder if you just wired it wrong or something?

Weird. These things are extremely simple to make (http://rtr.ca/yagi_antennas/index.cgi?z0205655+medium), and very tolerant of small measurement errors. I wonder if you just wired it wrong or something?
it worked but was lossy, meaning reception was worse than with a CM balun.
I used good quality RG6 and hooked things up exactly as per the instructions.
There's evidently some trick I'm missing

This design is for a "better antenna-tuner balun" that "promises advantages over both voltage and current baluns" (their quotes):

http://www.dxzone.com/cgi-bin/dir/jump2.cgi?ID=12661 (link goes to a 6 page technical document in PDF format)

Anything in there for TV Antenna fans?

link goes to a 37 page technical document in PDF format

?? I only got 6 pages ? Am I missing some ?

Sorry, I just changed it to say "6 pages" after I malfunctioned there... ;)

I reported on a handful of Balun loss "test" results here:
http://www.avsforum.com/avs-vb/showthread.php?p=13581150
[Sometimes you have to use what you have available....]
To add to holl_ands's post, I emailed him about it at another forum in 2007, and when I asked him where to buy the RMS baluns that did so well in his tests, he was nice enough to tell me that "The RMS baluns date back to Warner Cable in the early 80's"

has anyone actually used one of these, and if so can they verify that it's better (in the sense of lower losses) than the channel master baluns ?
it would be for use with a CM4228
to partially answer my own question, I came across Tin Lee's web page a couple of years ago and got a quote (so the prices are out of date).
I was looking for a balun for a CM4228, which gets high vhf as well as uhf.
Maybe I've misunderstood their quote, but they offered to sell me a "MT-37X 0089",
and at the end of the quote, it seems that this is simply a channel master balun ???

--- their emailed quote from 2007----
low-loss 300 -> 75 Ohm matching transformer for TV
(VHF channels 6+ and all UHF channels, from the same antenna)
1.5dB to 2dB loss from 50MHz to 800MHz (VHF/UHF)
Channel Master 75/300 ohm Balun with weatherboot
Price / ea $8.00 plus $20.00 shipping and handling (plus taxes)
-----

Wow, I didn't know that Tin Lee resold anything... maybe its a misunderstanding because the loss they quote is not the loss posted on the web site for their own balun model.

Wow, I didn't know that Tin Lee resold anything... maybe its a misunderstanding because the loss they quote is not the loss posted on the web site for their own balun model.
maybe it's the fact that I wanted high VHF as well as UHF that caused the problem.
The pdf quote definitely has their part number on the top and then the channel master specs on the bottom

I recently enquire with Tinlee about their channel specific low-loss balun, in my case it was for VHF 13. The reply was it is better to use a generic balun because it has a lower loss than a channel-specific balun.

However they mentionned that the advantage of a channel-specific balun is less interference from other frequencies

the price quoted was $75CA, which is quite more costly than a generic balun which is usually $1 to $5

http://www.digitalhome.ca/forum/picture.php?albumid=80&pictureid=496

I modeled a 4:1 balun using a halfwave of 75-ohm coax with the load centertapped and grounded. The load represents, for example, a folded dipole with its center electrically connected to the antenna boom and coax shield. Yagi antennas may use this configuration.

http://www.digitalhome.ca/forum/picture.php?albumid=80&pictureid=495

Mismatch loss at the band edges is twice as great as when the load is floating. I want to check the details of how the circuit analysis program models the transmission line, but if this result holds it provides a powerful incentive to insulate a driven element.

http://www.digitalhome.ca/forum/picture.php?albumid=80&pictureid=480

http://www.digitalhome.ca/forum/picture.php?albumid=80&pictureid=497

For reference, this is the floating-load model. Both models use a lossless transmission line. At UHF-TV frequencies the few inches of coax required for a halfwave balun should add negligible loss.

Brian

the one that really bummed me out was this:
http://www.dlsus.com/catalog/product_info.php?products_id=458
>> Specifications
>> -Bandwidth: 5-900 MHz
>> -Insertion Loss: 0.7 dB
>> -Return Loss: 16 dB
>> -Impedance: Input 300 Ohm, Output 75 Ohm
>> -Balance Ratio: 30 dB

I emailed to get confirmation (again 2007) and couldn't get a straight answer