RE: Wire and ferrite baluns

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From: Dave Richards (wr3i@earthlink.net)
Date: Sat Sep 28 2002 - 11:17:57 CDT


Karl,
        I am curious How do you use the 1:1 Balun on you 20 watt tuner?
Dave

-----Original Message-----
From: owner-qrp-l@Lehigh.EDU [mailto:owner-qrp-l@Lehigh.EDU]On Behalf Of
Karl F. Larsen
Sent: Saturday, September 28, 2002 11:38 AM
To: Low Power Amateur Radio Discussion
Subject: Re: Wire and ferrite baluns

Bill your trying to tell me that I do not understand and neither does
MFJ. All I can tell you is the following: I got a balun kit from LBJ
having a red powdered iron core and it was a 4:1 balun and did not work
at all on any frequency. I bought a uncolored ferrite core and rewound
the balun for 4:1 and it worked fine from 80 thru 10 meters. I then
reconnected it for 1:1 balun and it is working fine now on my antenna.

        I used a small ferrite core and made a 1:1 balun on my Dan's
Small Parts 20 watt T tuner I built. It works fine 80 thru 10 meters.

        All three of my MFJ antenna tuners have ferrite cores hooked up
as 4:1 baluns because it makes it convienient to bring out to connectors
in the back of the tuner. I reconnected one to 1:1 and it's working
fine.

        Please give me an example of a balun that works using a powdered
iron core. The Z-match is not a balun.

On Fri, 27 Sep 2002, Bill Coleman wrote:

> On 9/27/02 5:01 PM, Karl F. Larsen at k5di@zianet.com wrote:
>
> >As usual, your wrong Bill.
>
> I believe the converse is usually the case.
>
> >The MFJ-989 balun has a ferrite core. So does all my MFJ tuners.
>
> If it has a ferrite core, it cannot be a voltage balun. The windings
> would have far too much inducance to do the job properly.
>
> If the cores are ferrite, as you say, the MFJ tuners must be using a
> current balun. You cannot wire up a current balun to have a 4:1
> transformation ratio with a single core. (You can with two cores)
>
> Bottom line: the materials used for voltage and current baluns are
> different, and cannot be interchanged.
>
>
> >On Tue, 17 Sep 2002, Bill Coleman wrote:
> >
> >> On 8/5/02 8:21, Karl F. Larsen at k5di@zianet.com wrote:
> >>
> >> >It appears your MFJ-989C is quite a bit bigger than my MFJ-989
> >> >and has the coax wound balun while mine has the much smaller wire
toroid
> >> >type. It is easy to change from 4:1 to 1:1 if desired.
> >>
> >> Again, this is incorrect. You cannot just re-wire a 4:1 voltage balun
> >> into a 1:1 current balun. The voltage balun has a powdered iron core.
The
> >> current balun will use ferrite. The two materials are vastly different.
>
>
> Bill Coleman, AA4LR, PP-ASEL Mail: aa4lr@arrl.net
> Quote: "Not within a thousand years will man ever fly!"
> -- Wilbur Wright, 1901
>
>

--

- Karl Larsen k5di Las Cruces,NM Az ScQRPions -


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