"amdx" wrote in message
...

"Jerry Martes" wrote in message
news:yvJsi.35$zg3.14@trnddc04...

"amdx" wrote in message
...
I'd like to build the antenna from the following page;

http://www.frars.org.uk/cgi-bin/rend...62&goback=1064

But there are a few details I need to sort out before I try.



1) It uses UT141, Could I sub 9913?

2) Or, should I use the copper tube method shown here,

http://martybugs.net/wireless/biquad/

3) The author states:

"Next, cut four pieces of UT141 coax 80mm long, and strip 1.5mm of
outer from each end, leaving a total outside length of 77mm. These will
form part of the phasing assembly. Follow the diagram as to the
connection of these pieces of coax. Connection of two double quads in
parallel will result in an impedance of 25 ohms."



Please view 4double quad back jpg at bottom of page as reference.



I assume he's describing the 77mm pieces that run at a 45* angles,
however the picture does not show

UT141 coax as he describes.



4) Again the author states:

" Next for the 25ohm to 100 ohm matching sections, cut two pieces of
61mm UT141, again strip the outer back 1.5mm from each end to leave a
outside length of 58mm. Of course 2 100 ohm coax's in parallel will
result in an impedance of 50 ohms. Connect each piece to the joined 77mm
lengths as per the diagram. Under the connector, both centre conductors
from the 58mm lengths are connected to the centre pin of the SMA socket.
Solder the outer of these lengths to the SMA socket body to ensure a
good earth connection."



Again he says use UT141 but I don't see it in the picture.



I'm looking forward to your input!

Thanks, Mike

Hi Mike
You have given some great reference sites. Thanks.

Google is a friend to all!

If *I* was intending to feed two 25 ohm loads to a 50 ohm line, I'd
consider a series connection rather than transforming with a balanced
line transformer.

I don't really have a good understanding, but, looks like he has
two 50 ohm antennas connected thru two 77mm wires and then a repeat of
two 50 ohm antennas connected thru two 77mm wires. Then both sides are
connected
thru two 58mm wires to the center conductor of the connector.
(that all seems like 12.5ohms to me)
But I all ready know there is to much info missing here.


Besides, I didnt follow how the transforming of 25 ohms on a 100 ohm
line produced an impedance that is appropriate for matching to 50 ohms.
But, I havent studied the electrical equivalent lengths of the coax
lengths.

I know he talks about 100 ohm line but I don't see any.
I hope one of the gurus helps out on this.
Mike

I got some help offline (thanks Dave) the wires I thought were solid are
actually
a coax (UT141). It make a little more sense now.
Mike