"Ian White, G3SEK" wrote in message
...
Steve wrote:
All I need now is the plans for the antenna but I should have those
soon.

In about as long as it takes to go to the 'VHF/UHF Long Yagi Workshop'
on the site below. Some other questions will be answered there too.

Been there, done that. Couldn't find the measurements for the 4 wavelength
version. I have them now though from SV5BYRs site

Certainly a shorter sub-boom centred on the balance point is one good
way to go. Another is to use quarter-inch larger square tube for the
middle section, with the inch-square boom running right through, and
hard aluminium shims driven into the end. Don't forget to use a larger
boom correction for that centre section.

thanks for the advice.
It is much appreciated.
The only question I have now is probably a daft one but here goes....... the
plans for this antenna specify that the reflector should be at position 0 on
the boom and D13 should be at 8300mm relative to the position of the
reflector.. Where would one drill the hole for the reflector ? i.e how far
in from the end of the tube, and how far past the hole for the last director
would the boom actually end ?


--
http://www.ifwtech.co.uk/g3sek

Steve wrote:
The only question I have now is probably a daft one but here
goes....... the plans for this antenna specify that the reflector
should be at position 0 on the boom and D13 should be at 8300mm
relative to the position of the reflector.. Where would one drill the
hole for the reflector ? i.e how far in from the end of the tube, and
how far past the hole for the last director would the boom actually end ?

If the hole is far enough from the end that it doesn't weaken the
element mounting mechanically, that also seems to be OK as regards the
electrical effect of the metal boom.

It's nice to use plastic end caps (most yagi manufacturers will sell you
a few) so the practical distance for the holes is just far enough so
that the end cap will push in without fouling anything inside.

Or make it about pi/2 times the width of your thumb, and then trim the
end cap until it fits... no worries.


--
73 from Ian G3SEK 'In Practice' columnist for RadCom (RSGB)
Editor, 'The VHF/UHF DX Book'
http://www.ifwtech.co.uk/g3sek

It's nice to use plastic end caps (most yagi manufacturers will sell you
a few) so the practical distance for the holes is just far enough so
that the end cap will push in without fouling anything inside.

Or make it about pi/2 times the width of your thumb, and then trim the
end cap until it fits... no worries.


--
73 from Ian G3SEK 'In Practice' columnist for RadCom (RSGB)
Editor, 'The VHF/UHF DX Book'
http://www.ifwtech.co.uk/g3sek

Lovely. Thanks Ian.

Steve

"Steve" wrote in message
.. .
The only question I have now is probably a daft one but here goes.......
the
plans for this antenna specify that the reflector should be at position 0
on
the boom and D13 should be at 8300mm relative to the position of the
reflector.. Where would one drill the hole for the reflector ? i.e how far
in from the end of the tube, and how far past the hole for the last
director
would the boom actually end ?

There is a mechanical engineering standard on that. The issue came up re the
A310 design after the NY crash where the tail tore off . I believe the
standard is 2 hole diameters. I looked at my VHF beams, and they are about
25mm.

Tam/WB2TT