My MFJ-989C Tuner has the 1:1 Current Balun ...Of this I am sure. When
locating the balun just outside my WINDOW...we went with the same. No
problems HERE! All is working well.....
On Friday, July 12, 2013, Carl Moreschi <n4py3@earthlink.net> wrote:
> You read too much into what I said. All I was doing was giving a case
for where a 4:1 balun was better than a 1:1 balun. I wasn't talking about
using coax. I was talking about 600 ohm open wire line with a 4:1 balun at
the antenna end. And I was actually talking about a 4:1 transformer that
was balanced on both ends.
>
> I really don't want to get into this discussion, but there are many cases
where a 4:1 transformer is less loss than a 1:1.
>
> Carl Moreschi N4PY
> 121 Little Bell Dr.
> Hays, NC 28635
> www.n4py.com
>
> On 7/12/2013 11:23 AM, Rick - DJ0IP / NJ0IP wrote:
>
> Let's consider that one again, Carl.
>
> If we place a 4:1 balun at the feedpoint of the 80m antenna, then we have
> 625 Ohms "Unbalanced" at the feedpoint on 40m. the math is correct, but
> normally we would attach the coax to the bottom side of the balun, not
> openwire. The 625 ohms is a 12:1 SWR for the coax. So we don't want to
do
> that. And if we are going to run openwire, then we attach it directly to
> the antenna, we don't use a balun at that point.
>
> If we attach the openwire at the antenna and run it to the shack, into a
4:1
> balun at the tuner, just what value the antenna system exhibits at that
> point will depend on the length of the feedline. Granted it appears a 4:1
> balun would be a better match and usually it would be from an impedance
> standpoint. However if the SWR happens to be above 3:1 or so, the 4:1
balun
> quickly loses its ability to impede common mode current and that is very
> bad. The 1:1 current balun does not. Again as Jim says, we should be
> calling it a choke, not a balun but old habits die hard. So as long as
your
> matchbox is capable of matching whatever mismatch there is in the antenna
> system, it's better to use a 1:1 balun (for the sake of impeding CMC) and
> let the matchbox do the matching.
>
> The real problem is the other way around, when you attach openwire
feedline
> to a 40m dipole and attempt to match it on 80m.
> Now I know they recommend not to do this, but I've had a few QTH's where
it
> was my only way of getting on 80m. I didn't have enough space for
anything
> else, so I ran this and worked lots of DX with it on 80. But it creates
some
> real challenges for the balun and the matchbox:
>
> In this case the impedance is likely to be less than 10 Ohms at the
> matchbox, but it also depends on the length of the feedline. Let's call it
> 12 Ohms for the sake of easy math. The 4:1 balun at that point transforms
> it in the wrong direction, down to 3 Ohms. ALL matchboxes have high
losses
> when trying to deal with such low impedance. Just read any ARRL test of
any
> matchbox and check the internal loss at this impedance. Clearly the 12
Ohms
> will be easier to match than 3 Ohms. AND the 1:1 balun/choke (assuming it
> is adequate for the job) will do its job of impeding the common mode
> current, whereas the 4:1 balun will fail miserably.
>
> On top of that, the voltage balun fails in any case.
> The 238 has the wrong type of balun (voltage) and the wrong ratio (4:1).
> Don't use it.
> Use an external 1:1 current balun capable of dealing with the power level
> you are using.
> Jim (K9YC) has written an excellent paper on this topic. It is well worth
> reading.
>
> 73
> Rick, DJ0IP
>
>
> -----Original Message-----
> From: TenTec [mailto:tentec-bounces@contesting.com] On Behalf Of Carl
> Moreschi
> Sent: Friday, July 12, 2013 4:56 PM
> To: Discussion of Ten-Tec Equipment
> Subject: Re: [TenTec] OCF antennas evolution
>
> Let's say you are running a 80 meter dipole on 40 meters. The impedance
> will be about 2500 ohms or higher. Let's also say you are using 600 ohm
> ladder line.
>
> Then by placing a 4:1 balun at the antenna, the 2500 ohms becomes 625
ohms.
> That means you have an excellent match on the 600 ohm ladder line. You
then
> match the 600 ohm line to the rig with a tuner.
>
> The 4:1 balun in this case ends up with less loss than the 1:1 balun.
>
> It all depends on what you are matching as to which one is better.
>
>
>
> Carl Moreschi N4PY
> 121 Little Bell Dr.
> Hays, NC 28635
> www.n4py.com
>
> On 7/12/2013 9:15 AM, Bob McGraw - K4TAX wrote:
>
> I commented recently where there is indeed a good application for 4:1
> balun usage. I think you have also indicated the correct use for 4:1
> baluns in some of your OFC antenna discussions. In most other cases,
> typically 1:1 ratios are preferable. I know that Jim , K9YC, has some
> good information and history on correct balun usage. To complicate the
> topic, there are current baluns and voltage baluns both in 1:1 and 4:1
> configurations as well as other ratio version. You are correct in that
> the topic is rather complex and there's widely varying opinions,
> approaches and results.
>
> In my case balun usage is in the 50 ohm to 50 ohm unbalanced to
> balanced configuration where a matched condition always exist. Thus
> being on the input of the tuner.
>
> 73
> Bob, K4TAX
>
>
> ----- Original Message ----- From: "Rick - DJ0IP / NJ0IP"
> <Rick@DJ0IP.de>
> To: "'Discussion of Ten-Tec Equipmen
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