On Wed, 07 Sep 2005 12:50:11 GMT, W2RAC
wrote:
Thanks for the links
All elements are 3/16 rod and the DE is 7/16 tube.
Spacing is from the rear end of the boom measuring toward the front
end.
The best I can make of this isn't much improvement since the elements
for the most part are too short.
By cutting the reflector down to 41.5" there is some marginal
improvement in gain and F/B.
The existing design has G = 9.5 and F/B ~9.0.
With a 41.5" reflector, G ~ 10 and F/B ~ 10.3
If you could lengthen D1 and D2 to 37.5" and 36" respectively, then G
= 11.0 and F/B ~ 16, with a decent pattern.
This will be accompanied by a big lowering of feedpoint resistance,
which is to be expected.
On Tue, 06 Sep 2005 19:58:29 -0700, Wes Stewart
wrote:
On Wed, 07 Sep 2005 02:16:23 GMT, W2RAC
wrote:
PLEASE, I need help.
If anyone can run the numbers,
I have tried Quick Yagi with little success.
I have a pair of the OLDER Hy-Gain 2m antenna's. There design was a
200ohm Hairpin match (to 50ohm) with the reflector and
directors INSULATED from the boom.
Current model for the last 10+ years is the elements are not insulated
from the boom.
I want to respace the elements, possilbing cutting down as it is
easier than lenghting them, to get the best results for gain/pattern
I am only going to use them on 2M SSB with a center freq of 144.250
Here are the measurments.
14' boom
El Lgth Space
D6 34.62500 32.25
D5 35.00000 26.75
D4 35.12500 25.75
D3 35.12500 28.25
D2 35.25000 22.25
D1 35.50000 12.75
Driven 32.75000 16.75
Ref 44.37500 1.75
Notes. Measured in Inches. Reflector is mounted 1.75 inch from end of
boom, D6 is 1.5 inch from end of boom. All Elements are INSULATED on
top of the boom. If needbe I can remove 1 director as the insulator
need replacing.
It would be helpful (necessary) to know the element diameters and the
spacing from -one- reference point.
There are many "modern" designs published in the literature.
Boom correction factors for insulated/non-insulated elements are all
available on the web.
Practically everything you need to know can be found by starting he
http://www.ifwtech.co.uk/g3sek/diy-yagi/
One of the links:
http://www.k7mem.150m.com/Electronic.../yagi_vhf.html
might be especially helpful to you.