[TowerTalk] Spun director

[Doug Renwick]

Jim,

I have used my modified A3S on DXpedtions from 3D2DX, ZF1MM, VP2MRA and
8P9HG years ago. Was a good transportable beam antenna back then. Excellent
performer on 10 and 15m, not so good on 20m because of the short boom.

Doug

-----Original Message-----

<My ancient A3S (which I think I may have bought from VE9HF 25 yrs ago; and
it was old when I got it) keeps spinning the director.  No matter how many
times I tighten it - we get a good wind and there it goes.  It's currently
almost vertical.

Has anyone had any luck putting a hardwood (or PVC?, or other?) plug in the
end of the boom and tighten'r down against that and had this fix actually
work?

I feel the drinking straws at MacDonalds are likely thicker than the booms
on these old Cushcrafts, so I think that's really the problem.

 

Mike VE9AA

##  see below.

http://www.radiomanual.info/schemi/ACC_antenna/Cushcraft_A3S_user.pdf

http://www.cushcraftamateur.com/Product.php?productid=A-3S


http://www.cushcraftamateur.com/Product.php?productid=20-A3S-BB

##  Boom center section consist of a 1.625  OD x .058 wall x  12 inch long
section.
Boom end sections are 1.5 OD  x .058 wall  x  84 inchs long. 

##  They still  sell this tribander for a whopping $600.00    You can buy
one helluva lot of 
new tubing from DXE  for the same $600.00  then build something useful
.....like a F12  C3. 

##  If  cushcraft didnt invent fubar,  I dunno who did.   8dbd gain,  I dont
think so. 
500 khz swr BW, and no matching devices used.  Any 3 el monoband yagi does
not
have  a 50 ohm input Z, and neither does any tribander.   The losses in the
traps are sky
high.  Add those losses to the 15-25 ohm input Z...and then you get your 50
ohms...on  3 bands.
My guess is  CC is also growing marihuana in their broom closet sized
engineering dept. 
The suggested choke balun they depict would make K9YC gag.   Done their way,
you will get water
ingress into the braid..toast.  8 turns in a 6 inch diameter wont work
anyway. 

##  One possible solution is to use inserts into each end of the boom, since
they used 1.5 od x  .058 wall.
1.25 x .058 and 1.125 x .058  will  triple wall the ends. Unless you have
some scrap on hand, thats an 
expensive fix.     Or use some 1.25 inch wood dowelling..available anywhere.
Leave some of it sticking out
past the boom ends, so you have something to grab onto, if removal required.


## A solid saddle would go along way to maximize  surface area.   U bolts,
regardless of diam, have virtually
zero inner surface area.  U bolts are great..if you want to crush  tubing.
Sheet metal saddles are equally useless
devices, again, they have zero surface area. 

##  DXE sells U bolts and solid AL saddles.   You cant buy the saddles
separately, and their provided SS  U bolts
are the wrong diameter and way too short for this application.   However,
their  DXE-SAD-150A is a full 1 inch wide,
solid AL.  Although its designed for their mating 1/4-20  SS  U bolts, it
can easily be modified to handle the oem
CC  3/8 inch long  U bolts.   It would be a quick fix, and will be the end
of your issues.   But it appears the oem CC
saddles are curved on their undersides, to mate to the curvature of the
1.125 OD, so the solid DXE saddles may not work.
Grants idea of using machine screws to keep the oem saddles from splaying
apart  would help a lot.  

##  You would still have to be careful since  you are still  compressing the
1.125 od  x .058 wall eles.   They really need to
be double walled in their centers.    

##  Plan B  would be to use conventional  .25 thick  al plates.  With a pair
of  1.5 inch  DXE solid saddles +  SS u bolts to hold the boom to the
plate, then a 2nd pair of  1.250 DXE solid saddles + SS U bolts...to hold
the els to the plate.    DXE doesnt make  a 1.125 solid saddle.
The fix is to use their  1.250 saddles + SS ubolts, then slide a short piece
of 1.25  x .058 wall  tubing over the exact centers of the REF  +  DIR. 
https://static.dxengineering.com/global/images/chartsguides/d/dxe-sad-050a.p
df      This scheme would be 100 %  bullet proof. 

##  Is the A3S  supposed to be CCs answer to the Mosely  TA-33 ?   The
TA-33 is a solid  10 db down from a  Hy-gain 204BA.  That experiment has
been done at least  6 times here int own over the years.    I cant see the
A3S  being any better than the TA-33.   But at least CC used separate
15 +  10m traps. 

Jim  VE7RF 
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