K1TTT's site is superb, Dave has worked on that for years.
I dont care for the small bead sleeve baluns, measurements I took in the
80's were far from impressive.
Large beads which are about 1.2" diameter and 1.5" long with a .5" ID
work quite well over about 13-15" of RG-213/214, etc. Ive been using the
same baluns for over 20 years with no obvious deterioation but thanks
for the hint, I'll test then while Im rebuilding after the 12/5/08 ice
storm. And look into whats available in 31 mix from Fairite, I still
have an account there.
I consider a 30:1 impedance ratio between the feed impedance and the
balun to be sufficient at ham power levels thru at least 2500W. Others
consider anything over 1000 Ohms to be a lab exercise. Stacked arrays
and 4 Squares here work as they should and a RF sniffer gives the
feedlines a clean bill of health. Im probably more obsessive than most
when it comes to RFI/TVI, filters, baluns, stubs, etc and did most of my
studies and construction the 80's when building the contest station. Im
sure many have copied some of it as it was readily available thru
various club newsletters, snail mailings, OTA discussions and other pre
Internet means of getting information out.
A demonstration I used to give here was a 2-30 mHz reactive dummy load
built by National for checking 1-5 KW military amps. Crank in the
desired VSWR and see how the amp and feedline performed. A little hands
on work is a better teacher than books for many.
Carl
KM1H
----- Original Message -----
From: "Dan" <n5ar@air-pipe.com>
To: "Gary Smith" <wa6fgi@sbcglobal.net>
Cc: <amps@contesting.com>
Sent: Saturday, April 25, 2009 12:32 PM
Subject: Re: [Amps] Fw: High SWR
> Gary, I believe K9YC has the best designs for building your own sleeve
> baluns. The best available commercial baluns are those from DX
> Engineering IMO. If you would like a good summary of the balun
> situation
> I suggest you go to our clubs web page www.sdxa.org and click DX Tips
> on
> the right hand side to see my thoughts based on a study of the
> subject
> and measurements I have made. A link to K9YC's info is there.
> 73, Dan, N5AR
>
> Gary Smith wrote:
>> To the group:
>>
>> A giant thank you to all who answerd my question. Now I have to do
>> some reaserch on sleeve baluns as I am not (at all) familiar with
>> them.
>>
>> Again my thanks to a wonderfu group of indivuduals who are armed with
>> a cache of fantastic (and well appreciated) knowledge.
>>
>> 73,
>> Gary...wa6fgi
>> _______________________________________________
>> Amps mailing list
>> Amps@contesting.com
>> http://lists.contesting.com/mailman/listinfo/amps
>> ------------------------------------------------------------------------
>>
>>
>> No virus found in this incoming message.
>> Checked by AVG - www.avg.com
>> Version: 8.0.238 / Virus Database: 270.12.4/2080 - Release Date:
>> 04/25/09 08:29:00
>>
>>
> _______________________________________________
> Amps mailing list
> Amps@contesting.com
> http://lists.contesting.com/mailman/listinfo/amps
_______________________________________________
Amps mailing list
Amps@contesting.com
http://lists.contesting.com/mailman/listinfo/amps
|