[SCCC] ARRL SSB DX Contest

[Radiodan W7RF]

Hello John and the boys,

I concur with Mike and there is also some simple good practical balun
winding info at the Alpha Delta website.
See http://www.alphadeltacom.com/dxa_ii.htm 
Another great place to spend some educational hours is at W4RNL Cebik's
site.
See http://www.cebik.com/ 

The exact makup of the diameter and number of turns for a coax balun is up
for debate, Mike suggest 8T on a 6" form, I have used 10T or a 3-4" form up
to 8T on an 8" form. RG-213 is fine. Do NOT scramble wind, lay one turn next
to another. For lower frequencies (160-80-40M) I would use more turns and
larger diameter.

BN-86 balun is a voltage balun and will arc easily with any SWR and KW
power, like something as simple as tuning a CW 40M dipole on 40M SSB!

Another good choice are those ferrite core over teflon coax types (current
balun), like sold by Force-12, etc. Most of the common ones will be just
fine for 2500 watts and lower. Voltage breakdown with these types (current
balun) is less of a factor. Core saturation and subsequent heating can occur
with more power than they were designed to take.



Regards, Dan Magro W7RF
HENRY RF Power Amplifiers
BIRD RF power measuring, TOHTSU coaxial relays
SAMLEX power supply, RFI snap-on chokes
www.radiodan.com RFpower at radiodan.com 


-----Original Message-----
From: sccc-bounces at contesting.com [mailto:sccc-bounces at contesting.com] On
Behalf Of Michael Tope
Sent: Wednesday, March 08, 2006 6:15 AM
To: JOHN SCHROEDER; sccc
Subject: Re: [SCCC] ARRL SSB DX Contest


----- Original Message -----
From: "JOHN SCHROEDER" <n6qq at msn.com>

>
>            Heard  ZD8I, Jim most of the day Sat. on 15 meters - but 
> signal never came up to S2 - never could break that pileup.
>
>            As others, did work KH7X on 6 bands - only station I could 
> reach on 160.  Did you work YA1OJ on 20 meters.
>
>            Wiped out the Balun on the 40 meter 1 el hy-gain.  Need 
> suggestions for a higher power balun.

Let me guess, John - the rotary dipole used a BN-86 balun right? They are
notorious for being fuses. A coil of RG213 on a piece of plastic drain pipe
will work just fine (especially for a monoband antenna):

http://www.k1ttt.net/technote/airbalun.html

They recommend 12 turns on a 4" form. I would go with 8 turns on a 6" form.

If you want something a bit smaller, you can also buy current balun's from
DX Engineering or Array Solutions which use ferrite cores.

73, Mike W4EF....................................................



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