[50mhz] Yagis

[Carl]

Joe, how did you arrive at those gain figures? You claim 13.67 dBi for the 
stock A50-5S while CC states 10.5 dBi and my own YO 6.5 analysis in the 90's 
comes up with 9.87 dBi.  I used 50.135 MHz and CC didnt state a frequency 
which can account for the small difference as they probably quoted peak gain 
at some frequency above 50.5 which is where I stopped plotting. You and I 
agree very closely on the F/B and feed impedance.

Your extended plot and element arrangement agrees very close with a similar 
extension I did, also in the 90's, with a resultant 11.3 dBi at 50.135.

Tweaking the stock antenna on the same boom length I arrived at a miniscule 
gain increase to 10 dBi but improved the total F/R to 28.5dB which was my 
goal. It seems that a roughly 1.4 dB increase by extending the boom buys 
very little gain unless used in a stack.

Carl
KM1H



----- Original Message ----- 
From: "Bill VanAlstyne W5WVO" <w5wvo at cybermesa.net>
To: "Mark D. Tetrault" <mdtetrault at gmail.com>; <50mhz at mailman.qth.net>
Sent: Monday, August 23, 2010 9:34 PM
Subject: Re: [50mhz] Yagis


> Mark,
>
> If cost is a significant factor in your decision, you might consider
> modifying your A50-5S yagi according to my design. It will cost you about
> $20 max. It has been done by scores of amateurs with good success. The
> computer-modeled design will give you a yagi very similar in appearance 
> and
> performance to the M2 6M5X. All you have to buy or otherwise procure is a
> 6-ft length of 1-1/2" x 0.058" wall aluminum tubing to extend the boom and 
> a
> couple of hose clamps. Everything else is just changing design dimensions
> and readjusting the gamma match.
>
> You can find the paper here:
>
>   http://www.joeunkit.co.kr/upload/upload251/A50-5S_w5wvo.pdf
>
> I don't know who this Korean site is, or how my paper got on it, but...
> there it is. :-)
>
> Bill W5WVO
>
> --------------------------------------------------
> From: "Mark D. Tetrault" <mdtetrault at gmail.com>
> Sent: Monday, August 23, 2010 22:18
> To: <50mhz at mailman.qth.net>
> Subject: [50mhz] Yagis
>
>> OK I'm having mind fart.
>>
>> I've used Cushcraft's 5 element yagi for years with good results. I
>> have now moved to AZ and will be putting up a 35' tower. My CCraft 5
>> el is getting old so time to eihter replace it with a new one, or buy
>> something else.
>>
>> Trouble is I cannot remember all the yagis that are recommended. I
>> know M2 builds a good one. Who else should I consider?
>>
>> Tnx,
>> Mark
>> AA1OV
>>
>>
>>
>> Di-Mar Imaging & Design
>> Quality Campground Maps & Brochures
>> Concord, NH
>> (603) 387-9392
>> www.di-mar.com
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