Re: [amsat-bb] Homebuilt Arrow Antennas?

[Rick Abbott <kb0lgb@xxxxxxxxxxx>]

Steve and list,

I have had the same idea and had a home-brew ATV 421 MHz 13 element not
being used (pg48-51 feb99 CQ VHF magazine article by WA5VJB on cheap
yagis). I chopped it in half leaving 7 elements and today (hopefully)
will be adding the 3 element 2m yagi (depicted in 1999 ARRL handbook pg
20.59). 
I tested the newly chopped 7 element for receive of a UO-14 pass
standing atop a snow bank in my driveway with my FT-470 HT and heard the
whole pass! This was a 13 degree pass and was copied through the
leafless winter trees and among neighborhood houses etc.. I have never
heard a whole sat pass with my terrestrial antennas in the shack without
fading. Hand holding and twisting here and there really brings it in! I
was shouting out the states/prov to my kids as I heard grid squares: CA,
TX, Ont!!

I built the  ATV antenna using wood stock boom and aluminum ground wire
sold near the TV antennas in any hdwr store. The driven element is #12
copper. You stiffen the wires by putting one end in a vise and the other
in your drill chuck and twist it slowly about 3-5 turns while pulling
slightly (be sure to cut them quite longer then needed).

For the 2m elements I chose 1/4" aluminum stock and will try using 1/4"
OD brass compression unions as the mid point for ref and dire elements.
The driven elements will be fastened to the boom with aluminum "set
screw" type grounding blocks. 

What I have not figured out yet is how to commonly feed this
arrangement. The 420 beam driven element is essentially a j-pole (shield
and center pin feed electrically shorted). The 2m beam design is a
dipole (feed open). I was thinking of parallel feed but not sure what
the 420 short will do to the 2m dipole (RF wise that is). So anyone with
ideas here please advise. 

I have dubbed my design "one H.O.T. antenna" HOT=handheld orbit
tracker", so you heard it here first :-)

73 and have fun experimenting,

rick-kb0lgb


"Brockwell, Stephen E. CECOM SEC FSSE ILEX" wrote:
> 
> Someone on the list had (I believe ... but I have been known to
> hallucinate..) built a version of the famous Arrow dual band yagis for sat
> work and had posted a little info in the last couple of months.  Are there
> any building instructions or pictures?  I can tell you what I've done so
> far.
> 
> I wanted a take-down portable 2m/70CM dual band yagi for satellite work and
> general rovering VHF/UHF.   I started getting some gear together for that
> project and so far have some Easton 1916 aluminum arrow shafts (flea market
> 25 cents each), threaded inserts for the shafts (50 cents each at archery
> store), 2.5 inch long 8/32 machine screws to fit the threaded inserts (6
> cents each at my favorite hardware store) and some nuts to fit the screws.
> Next step is to get some aluminum angle or square stock for the boom.  Use a
> tubing cutter to carefully cut the arrow shafts to size and use some type of
> goop on the end to seal the shaft..(and keep from PUTTING MY EYE OUT... been
> there almost did that!)
> 
> On the XE1MEX web site there is a good drawing of the gamma match for
> building yagis and I won't even pretend that I understand gamma match yet
> but I'm working on it.
> 
> Later I want a take-down 10 meter crossed dipole for quick deployment to
> receive the RS sats and modify my TenTec 10m-2m transverter and RS HTX-10
> combo to cover the satellite band area.  (right now it only goes to 29.699
> mhz ..... bummer..)
> 
> If anyone knows of homebuilt Arrow type antennas please let me know ....  I
> will share what I do and what I've learned...
> 
> 73  Steve  KC5TTY
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