On Sun, 13 Mar 2005 08:46:04 +0800, "muskie"
wrote:
1. Detail information about the hairpin. match (i.e. length, the distance
between the 2 legs and the location to solder)

Hi OM,

You should have some form of a design in front of you, even if it is a
copy of an advertising brochure to work from. At this scale, it is
pretty simple to build a working model, but first observe the answer
to question 4 below.

2. The feedline should be even or odd 1/4 wavelength?

If you did your matching right (this is the answer to question 3), it
won't matter. However, you cannot tell if you did the matching right
until you get to question 4 below.

3. When solder the feedline to the hairpin, what's the location?

This is one of those variables that you determine when all else is
done. As such it requires a SWR meter (see how these issues cascade
to your tools?).

4. If I don't have the SWR meter, is it still possible to build the Yagi?

With as much cut-and-try, you need more tools than a screwdriver and
pliers. Building to a scaled model only goes so far when you have to
actually perform a sanity check. The SWR meter will tell you how well
the design matches to the power transfer from a transmitter, a notable
performance variable, but not the only one.

I did the search for a month on the net and newsgroup, but still don't have
any luck to give me the answers. Thanks for any comment in advance!!!

When you build your own, each construction is its own masterpiece.
The only way to guarantee performance is to build an identical copy.
You can buy a model, but then you wouldn't need to build one after
that.... There's as many models as there are characteristics that you
want to optimize. So, you have to FIRST determine, what
characteristics are important, THEN find the model (or build one in
software, then in copper, then one that is weatherproof).

The simple resolution is to invest in tools and expect to go through
at least a couple or three designs. That is, for a yagi style. There
are simpler designs that work the first time - but you didn't ask THAT
question.

73's
Richard Clark, KB7QHC