Hi,

I made the antenna out of a wood beam and 1/4" brass stock.
I used the QY4 program and the utilities program. Used some solid
18 gauge wire for the gamma match with a 4.7pf capacitor.
QY4 recommended 4.2pf. I used a small plastic box to house the
BNC connector, the gamma wire and the capacitor. Looks pretty
professional actually.
Well, I had set the program to optimize the antenna for 433Mhz
as that is what I was going to start with on my tracking transmitter.
Plugged the Yagi into my handheld, set the power to low, set the fwd
indication on my SWR meter and then did the ref reading. I was shocked
to see that it was 1:1.2. Set it up to 450Mhz and saw it was 1:1. For
this new ham, it was pretty surprising for a first project.
Will be using the antenna mainly to track an RDF beacon in an amateur
rocket. The link is here if your curious to see the unit. They make one
that transmits GPS data too. http://bigredbee.com/BeeLine.htm
Did some testing and I don't have as much directivity but I sure as
heck have plenty of gain with this setup. I might have to get a loop
if a model gets lost in some high weeds so I can get a better bearing
close-in.
I probably won't need an attenuator as I know the Foxhunt RDF folks
intentionally hide their transmitters in some weird places. Our rockets
most of the time land in an open area where our launchsite is.
Sometimes a high powered ship simply disappears off the pad and no one
sees it land. That's when the onboard RDF transmitter earns it's keep.
So far no one has lost a transmitter equipped rocket and there have
been several occasions where this has happened.
One person taped his transmitter to the shock cord that tethers the
pieces of the rocket under the parachute. He recovered his rocket,
brought it back and discovered no transmitter. They had been receiving a
signal all along but the model landed within sight. They went back out
into the field and found the still beeping transmitter with the loop
equipped receiver. Seems it was ripped off the shock cord and fell a
few thousand feet unharmed. This is where amateur rocketry can become
like an RDF foxhunt. :-)

Kurt


Sal M. Onella wrote:
"Kurt" wrote in message
. ..

Hi,

Am trying a homemade 7 element handheld beam I'm making for 70cm
with .25" brass stock. Have a little junction box I have mounted on
the beam with a male socket so I can use a BNC cable for the radio
connection. Does it matter what size/type wire I use to connect the
socket to the brass element and the Gamma match element inside the
junction box? I want to use a socket so I can use different lengths of
cable as opposed to hardwiring the cable to the antenna.



I read the other responses and have no quarrel with them. However,
I have seen a commercial uhf yagi with a gamma match. It was on
the side of a building and was probably cut for the 450 - 470 MHz
business band; it looked just a bit smaller than my 70 cm antennas.

My point: It can be done, assuming the antenna I saw wasn't a
total POS!

73
"Sal"
(KD6VKW)