KX3 - 1:1 balun

[Steve KC8QVO]

I have a few Amidon T80-2 toroids and plan on making a 1:1 balun. I guess I really have 2 questions.

1. Would insulated wire work OK to wind it with or is it really necessary to use enamel coated magnet wire? I have some #28 or so (cuttings from computer ribbon wire) that may work out well (already bonded through the length of it, dual conductor parallel runs). If not I have some 18 gauge gold color magnet wire.

2. I am going to use a BNC connector for the rig side. I am thinking of putting a pigtail of LMR-100 (maybe 4-6") to the connector, but if it is going to be too lossy or cause the impedances to be too far out of whack I won't worry about it and make the balun a direct box off the side of the rig.

My last question is if there are any good triple ratio balun designs. I want the 1:1 to match doublets, but a 2:1 and 4:1 ratio would allow a bit more flexibility in impedances.

Steve, KC8QVO

[w0ih]

Steve,

1. I've seen baluns made with insulated wire, I don't think that it makes any difference.
  http://www.collegearc.com/index.php?option=com_content&view=article&id=165:building-a-current-balun&catid=77:technical

2.  I would keep the coax between the rig and the balun short.  There could be some very high SWR's on that piece of coax.  You could try to design the balun box to connect directly to the rig output, but I can't see where a short piece would make that much difference. (I'm assuming that you have the internal tuner on the KX3.)

3. As for the triple ratio balun designs, I built a balun recently using an Amidon kit.  The kits typically come with a spec sheet that has about 8 different designs.  You can also look up the designs in the ARRL Handbook. The design that I used has a 200, 450 and 800 ohm output tap and it's also possible to tap at other ratios (1.5:1 to 16:1).   I plan to use it with a W3EDP antenna design.   Mine is a 2kw core, but you could easily adapt it to a smaller core.

If I'm not mistaken, you have KX3 SN 687, I have 688...

Mike
  W0IH

[Barry K3NDM]

Steve,
A 1:1 balun is really a choke/isolator or some other names. If you are not going to use outdoors in wet weather. I wouldn't worry about doing anything elaborate. I would just wind as many turns of the LMR-100 as you can on the torroid. Put a female connector on one side and prepare the other side for ladder line.

If you hadn't already purchased the core, I would have recommended just winding about 10-12 turns of your coax on a piece of PVC pipe, at least 10X the diameter of the coax and long enough to conveniently hold the turns. I use this regularly as it is cheap and it works. If you need an impedance transformation, you will need to be a little more serious.

73,
Barry
K3NDM

----- Original Message -----
From: "Steve KC8QVO" <[hidden email]>
To: [hidden email]
Sent: Wednesday, July 18, 2012 7:13:54 PM
Subject: [Elecraft] KX3 - 1:1 balun

I have a few Amidon T80-2 toroids and plan on making a 1:1 balun. I guess I
really have 2 questions.

1. Would insulated wire work OK to wind it with or is it really necessary to
use enamel coated magnet wire? I have some #28 or so (cuttings from computer
ribbon wire) that may work out well (already bonded through the length of
it, dual conductor parallel runs). If not I have some 18 gauge gold color
magnet wire.

2. I am going to use a BNC connector for the rig side. I am thinking of
putting a pigtail of LMR-100 (maybe 4-6") to the connector, but if it is
going to be too lossy or cause the impedances to be too far out of whack I
won't worry about it and make the balun a direct box off the side of the
rig.

My last question is if there are any good triple ratio balun designs. I want
the 1:1 to match doublets, but a 2:1 and 4:1 ratio would allow a bit more
flexibility in impedances.

Steve, KC8QVO

--
View this message in context: http://elecraft.365791.n2.nabble.com/KX3-1-1-balun-tp7559405.html 
Sent from the Elecraft mailing list archive at Nabble.com.
______________________________________________________________
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft 
Help: http://mailman.qth.net/mmfaq.htm 
Post: mailto:[hidden email]

This list hosted by: http://www.qsl.net 
Please help support this email list: http://www.qsl.net/donate.html 
______________________________________________________________
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:[hidden email]

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html

[Don Wilhelm-4]

Steve,

Make, build, or buy a good 1:1 current balun.  Wind several turns of
coax through the core and you have it.

Now, if you need an impedance transformer, you can make one from the 2nd
core wind a primary and a secondary winding to obtain whatever impedance
ratio you want.  connect the transformer primary to the output side of
your 1:1 choke balun and the secondary side to your balanced feedline.

So the "wire" for your 1:1 balun is the coax, and the wire for the RF
impedance transformer can be regular wire, insulated with enamel of some
other material, it is not likely to matter.

73,
Don W3FPR

On 7/18/2012 7:13 PM, Steve KC8QVO wrote:

> I have a few Amidon T80-2 toroids and plan on making a 1:1 balun. I guess I
> really have 2 questions.
>
> 1. Would insulated wire work OK to wind it with or is it really necessary to
> use enamel coated magnet wire? I have some #28 or so (cuttings from computer
> ribbon wire) that may work out well (already bonded through the length of
> it, dual conductor parallel runs). If not I have some 18 gauge gold color
> magnet wire.
>
> 2. I am going to use a BNC connector for the rig side. I am thinking of
> putting a pigtail of LMR-100 (maybe 4-6") to the connector, but if it is
> going to be too lossy or cause the impedances to be too far out of whack I
> won't worry about it and make the balun a direct box off the side of the
> rig.
>
> My last question is if there are any good triple ratio balun designs. I want
> the 1:1 to match doublets, but a 2:1 and 4:1 ratio would allow a bit more
> flexibility in impedances.
>
> Steve, KC8QVO
>

______________________________________________________________
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:[hidden email]

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html