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[TowerTalk] Cushcraft Parts From MFJ

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Subject: [TowerTalk] Cushcraft Parts From MFJ
From: "Jim Thomson" <jim.thom@telus.net>
Date: Thu, 25 Nov 2010 01:40:16 -0800
List-post: <towertalk@contesting.com">mailto:towertalk@contesting.com>
Date: Wed, 24 Nov 2010 13:30:39 -0600
From: Chuck <Chuck@dxham.net>
Subject: Re: [TowerTalk] Cushcraft Parts From MFJ

On 11/24/2010 1:00 PM, Larry & Karen wrote:

I immediately thought of  putting up a HyGain 6M antenna, so 
I called  Burghardt's and they sent me one right down.

The antenna LOOKED just like the ones made in Lincoln so I proceeded 
with the assembly and installation. Many small parts and lots of 
measurements and adjustments later, I had the beam mounted atop my 100ft 
tower. The antenna performed as I expected a 4el beam to perform. SWR 
was reasonable.....for awhile.

Here on the plains of Western Iowa, we get frequent high winds and many 
storms. One day, I decided to get on 6 meters and make some contacts and 
my SWR was way out of whack. I went out back to the tower and saw that 
half of one of the elements was totally MISSING! I found it out in the 
corn field a little ways from my tower.

####  Did the ele  to boom clamp break,  or did the ele  just snap off,
right at the boom to ele clamp ??    What was the wind-speed ? 


Unfortunately, after dropping the antenna down and replacing the element 
with one I had on-hand, we reinstalled it only to have a different 
element break off a couple weeks later! All in all, I lost 4 half 
elements in less than 6 months. We yanked it down, boxed it up and off 
it went back to Burghardt's! What a wonderful company! Jim credited me 
the full price towards a new 5 element M2 6M5X beam, which I installed 
in the spring. What a difference! The M2 antenna has been up for 8 years 
now and performs flawlessly!

##  This is bloody  awful !   But that was >8 years ago too. 
All you have to do is insert all the entire  ele  tubing schedule,
OD's, ID's, various wall thickness's, AND  yield strengths, alloy's, temper,
into  YS 2.15 OR the DX eng software,  or  ON4UN's  software, and it will  tell 
you 
exactly how much wind it will take, [with and without XXX ice]..and also
tell you exactly WHERE it  will break.  

##  My guess is, instead of using  6061-T6  or  6063-T832,  they have  gone
to a cheap alloy, like  3003,  which comes in various grades of hardness, listed
as  H-0  to H-14.    H-0   is only 6 ksi yield, and the  strongest is no match  
for 
6061-T6  or  6063-T832.    3003  H-0-3  is  used for  refrig tubing..and comes 
in 50'
rolls !     Another  famous  US  ant maker tried  using 3003 [ H unknown], for  
ele 
tips, and all the  tips  failed !   

##  a local ham  went  dumpster diving at the local airport, where an aircraft 
rebuild
business is located,  and obtained enough tubing  to build 2 x 15m  yagi's.   
In the
1st wind storm,  ALL the ele's bent badly... right at the boom !    Turns out 
he had
pilfered  2024-T0  tubing.....which has  zip for yield strength.    Normally,  
2024-T0
is  1st bent into various U shapes, for small  aircraft tail sections, then  
drilled, bent,
etc, etc,... THEN  sent in for heat treating...where the max you can heat treat 
2024
is T-3   [ aprx 45 ksi yield].     2024-T0  has  very little  yield strength, 
which is not readily
apparent when building yagi ele's.  

Chuck  K?TVD


> I have to agree with Ted on the quality of MFJ.  I have had both the old and
> the new Hy Gain for example and my experience with the new has never been
> good.  They have cheapened the HY Gain line to the point where it is
> basically junk.   For example, I can  understand and element breaking off in 
> high winds,
 but the last two feet of  the element out at the end?  Twice?  Take a six foot 
section of the boom of
> any MFJ/HY Gain tribander and hold it in one hand and in the other hold the
> exact same piece of an actual HY Gain boom from the past and tell me which
> one you want to put in the air.  No contest.

##  OK, is the wall thickness the same ?   Or did they reduce it ?    I assume 
the OD is still
the same ?   My old  6-el  F-12 yagi only weighs 45 lbs..and boom  consist of  
6 x 6'  sections,[all 2" OD]
nose to tail, with outer  sleeve splices.     They used  .125"  then .058", 
then  .049"   for the boom
[repeat for  other 1/2].    YS-2.15   says the boom is good for  122 mph.   
F-12 uses  6061-T6  for
booms  and eles.    The new  F-12 stuff uses  bigger diam and thicker wall 
booms.   They have also done
away  with all the  .049" wall tubing and ele swedging, and have  gone to all  
.058" wall  stuff.... including the
3/8"  OD tips.  [ old tips were all .035"  wall].  

##  IMO... unless  Hy-gain/ MFJ  can  state the exact alloy  and temper  of 
both their booms  and  els  [and those
flaky clamshell boom to ele brackets]... I would not touch their ant products.  
 It appears they have either used 
a cheaper alloy /and /or the old alloy, but a softer temper... or both.   IF  
we knew what alloy/temper/yield strength
they used,it would take all of 2 x minutes for the software  to spit out  
exactly what windspeed it will break at. 
6M  els, made from  3/8"  and  1/2"  tubing  [6061-T6  or  6063-T832]  are good 
for > 100 +++ mph easily. 
Lemme guess, the pricesare the same, or slightly more than the original 
hi-gain's ?    This is probably  a
case of [A]  use  cheap AL  for the boom and eles... and  [B]  keep the price 
the same, and [C] therefore enhance profits.
Joe ham  will not have a clue  what alloy /temper his shiny new  hi-gain yagi 
is built  from.    New/old Hams 
will then assume that broken els  in 65-80 mph winds is ...'normal'.    It's  
not folks.  
They are selling you a bill of goods, plane and simple.   US  products  are 
very expensive outside the usa, esp ants,
and that's a lot of money down the drain. Shipping costs  to sent the old junk  
back to the factory, and back again, is
cost prohibitive...and a waste of time.  IE:  no  point in replacing a damaged 
mfj / hi-gain  yagi, with a 2nd, identical
one. 

later.... Jim   VE7RF


> 73, Larry  K0IS



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