[RTTY] High power baluns

[Joe Subich, W4TV]

Don't use any of the "Maxwell" type ferrite beads over coax particularly
for RTTY.  The beads overheat and fail - see the information on baluns
at www.w8ji.com.

Here is an excellent note on using the "coil of coax" approach with
measurements of choking efficiencies across the HF range:
http://dayton.akorn.net/pipermail/towertalk/1996-August/000644.html

73,

    ... Joe, W4TV




> -----Original Message-----
> From: rtty-bounces at contesting.com
> [mailto:rtty-bounces at contesting.com] On Behalf Of Jim Martin - MM0BQI
> Sent: Wednesday, February 15, 2006 10:06 AM
> To: rtty at contesting.com; Jerry Pixton
> Subject: Re: [RTTY] High power baluns
>
>
> Hi Jerry
> Make your own and save a fortune!
> I have parallel dipoles for 80-10m.  The balun is about 9
> turns of coax formed on a piece of 4 inch drain pipe.  This
> works a treat and if you are using RG8/ RG213 type coax there
> is no loss or problem running full power.
> The other option is to use a stack of ferrite rings along the
> coax, works just as well.  I have tried a few commercial types
> which got hot and died so
> I would not go down that route again!
> Try this page for more information http://www.cebik.com/a10/ant47.html
> 73
> Jim,  MM0BQI
>
> ----- Original Message -----
> From: "Jerry Pixton" <jpixton at shentel.net>
> To: <rtty at contesting.com>
> Sent: Wednesday, February 15, 2006 12:42 PM
> Subject: [RTTY] High power baluns
>
>
> > All HP rtty users with dipoles, etc,
> >
> > I discovered the problem I was having on 80m during wpx
> where the SWR
> > would
> > suddenly rise. I thought it was the snow shorting across the folded
> > dipole.
> > But in the day light Monday, I see the "load/terminator" at
> the ends of
> > the
> > folded dipoles is badly scorched. And I can see the SWR
> rise under heating
> > from the linear's RF.
> >
> > So my question for you dipole users is -  What type of high
> power baluns
> > (one to one, I suppose) are you using to make your dipoles?
> >
> > I have always liked the parallel dipole arrangement where I
> can get all 5
> > bands between two end supports with the tower holding the middle.
> >
> > All the baluns I am seeing are rated "at full legal power"
> but then they
> > are qualified as ssb/cw duty cycle only. And some go so far
> as to say "not
> > for rtty".   So what baluns will take 1.5 kw rtty
> continuous service?
> >
> > New antennas are going to have to be built
> >
> > Jerry
> > ------------------------------------------
> > Dr. Jerry R. Pixton, PIXOS Designs LLC
> > http://www.pixos.com/designs/RadioTuner/
> > jpixton at shentel.net
> > ------------------------------------------
> >
> >
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