I don't know whether I've got the know-how or the time to design a homebrew
VHF yagi for the marine band.

So, is anyone out there interested in providing a service to all marine band
DXers/eavesdroppers of designing and producing *full constructional notes*
on a range of marine antennas, and then putting the designs up on a website.

All antennas shall principally be for reception.

All antennas should be described as covering 156-162Mhz.

As far as the yagis are concerned, they should range from 2 to 6 elements.

All yagis shall have 4mm (or 3/16") diameter parasitic elements.

All parasitic elements shall be secured to boom by nylon rivets as per
G3SEK's notes at:
http://www.ifwtech.co.uk/g3sek/diy-yagi/#Construction

All booms shall consist of either 20mm or 15mm square tubing.

The DE for all yagis shall be 8mm (or 5/16").

The DE for all yagis shall be a regular hertz dipole.

There shall be some kind of balun.

Please, please!

"Richard" wrote in message
...

All yagis shall have 4mm (or 3/16") diameter parasitic elements.

I think this is reasonable. It will keep the antenna lightweight. Why have
bigger if you don't have to.

The DE for all yagis shall be 8mm (or 5/16").

Possibly this could be 3/8" because this size might generally more easily
available.

The DE for all yagis shall be a regular hertz dipole.

Why have a folded dipole if you don't have to.

How are you going to mount DE? Are there any commercially availble dipole
centers that take 5/16" or 3/8" tube? Will you have to homebrew the dipole
center peice?

(In UK I can obtain commercial dipole centers that hold 1/2". I've not
sourced any others that take 5/16" or 3/8").

I don't know whether I've got the know-how or the time to design a homebrew
VHF yagi for the marine band.

So, is anyone out there interested in providing a service to all marine band
DXers/eavesdroppers of designing and producing *full constructional notes*
on a range of marine antennas, and then putting the designs up on a website.

All antennas shall principally be for reception.

All antennas should be described as covering 156-162Mhz.

As far as the yagis are concerned, they should range from 2 to 6 elements.

All yagis shall have 4mm (or 3/16") diameter parasitic elements.

All parasitic elements shall be secured to boom by nylon rivets as per
G3SEK's notes at:
http://www.ifwtech.co.uk/g3sek/diy-yagi/#Construction

All booms shall consist of either 20mm or 15mm square tubing.

The DE for all yagis shall be 8mm (or 5/16").

The DE for all yagis shall be a regular hertz dipole.

There shall be some kind of balun.

Please, please!


Just out of curiousity, why can't these be purchased already from commercial
sources? Note: I am not in the 'lawn furniture in the sky' business.

73,
Chip N1IR

"Richard" wrote in message
...
I don't know whether I've got the know-how or the time to design a
homebrew
VHF yagi for the marine band.

So, is anyone out there interested in providing a service to all marine
band
DXers/eavesdroppers of designing and producing *full constructional notes*
on a range of marine antennas, and then putting the designs up on a
website.

All antennas shall principally be for reception.

All antennas should be described as covering 156-162Mhz.

As far as the yagis are concerned, they should range from 2 to 6 elements.

All yagis shall have 4mm (or 3/16") diameter parasitic elements.

All parasitic elements shall be secured to boom by nylon rivets as per
G3SEK's notes at:
http://www.ifwtech.co.uk/g3sek/diy-yagi/#Construction

All booms shall consist of either 20mm or 15mm square tubing.

The DE for all yagis shall be 8mm (or 5/16").

The DE for all yagis shall be a regular hertz dipole.

There shall be some kind of balun.

Please, please!

If I was going to put up an antenna like that, I would look for a used
CushCraft 2m 7 element antenna, and cut it down. I once bought one for
U$7.00. Several years ago QST had an article on making a VHF TV antenna work
on 2M; Changing that to 156-162 instead should be simple.

Tam/WB2TT

"Richard" wrote in message
...

So, is anyone out there interested in providing a service to all marine
band DXers/eavesdroppers of designing and producing *full
constructional notes* on a range of marine antennas, and then
putting the designs up on a website.


This would probably be the start of your 6 element design:

Parasitic elements 4mm dia rod , DE 8mm or 5/16" tube.

------------------|------------------- R 37.106"
| ^ 0.000"
------------------|------------------ DE 36.772"
| ^ 9.275"
------------------|------------------ D1 34.154"
| ^ 12.250"
------------------|------------------ D2 33.34"
| ^ 23.800"
------------------|------------------ D3 33.34"
| ^ 34.213"
------------------|------------------ D4 32.58"
^ 47.211"


IOW:
X Y Z Dia"

REF End 1 0.000 -18.553 0.000 0.187
End2 0.000 18.553 0.000


DE End1 9.275 -18.368 0.000 0.312
End2 9.275 18.368 0.000


DIR1 End1 12.250 -17.077 0.000 0.187
End2 12.250 17.077 0.000


DIR2 End1 23.800 -16.672 0.000 0.187
End2 23.800 16.672 0.000


DIR3 End1 34.213 -16.672 0.000 0.187
End2 34.213 16.672 0.000


DIR4 End1 47.211 -16.229 0.000 0.187
End2 47.211 16.229 0.000


Boom 15mm square, 50" long.

Parasitic elements slotted through boom with nylon rivets system.

DE using commercial dipole center peice.

DE hertz dipole with some kind of balun arrangement.

Potential problem?: Parasitics slot through boom because they are held in
place (say) by the nylon rivets system, DE will *not* pass through boom but
above it. Will that make a difference?

As you see I have some dimensions given me, but I have no skill to take
these dimensions (assumimng I stick with them) as a starting point and
produce an actual constructional design.

So, is anyone out there interested in providing a service to all marine band
DXers/eavesdroppers

Why, exactly, is there a need to 'eavesdrop'? Who, in particular, are you
trying to 'eavesdrop' on? How many 'eavesdroppers' would seek such 'service'?

I am confused by your motivations and would be better enlightened with more
info in this regard. I ususpect I am not alone in this confusion.

Many thanks,

73,
Chip N1IR

"Fractenna" wrote in message
...
So, is anyone out there interested in providing a service to all marine
band
DXers/eavesdroppers

Why, exactly, is there a need to 'eavesdrop'? Who, in particular, are you
trying to 'eavesdrop' on? How many 'eavesdroppers' would seek such
'service'?

I am confused by your motivations and would be better enlightened with
more
info in this regard. I ususpect I am not alone in this confusion.

Many thanks,

73,
Chip N1IR

Oh you got me! I've been caught out! I'm listening to the marine band. Shall
I expect the police at my door? Quickly I must hide my apperatus! I think
not.

"Richard" wrote in message
...

"Richard" wrote in message
...

So, is anyone out there interested in providing a service to all marine
band DXers/eavesdroppers of designing and producing *full
constructional notes* on a range of marine antennas, and then
putting the designs up on a website.


This would probably be the start of your 6 element design:

Parasitic elements 4mm dia rod , DE 8mm or 5/16" tube.

Actually, the figure for the parasitics were given as 0.187" dia. that's
about 4.75mm or nearer 5mm than 4mm.

Dear Richard - no full name - no call - no location - probably not a
real E-mail address:

Let me see if I understand: You have the strange idea that someone
who has the experience and skill to craft for you an expensive design
(for free) is looking for something to do. Strange indeed.
Mac N8TT
--
J. Mc Laughlin - Michigan USA
Home:

"J. McLaughlin" wrote in message
...
Dear Richard - no full name - no call - no location - probably not a
real E-mail address:

Let me see if I understand: You have the strange idea that someone
who has the experience and skill to craft for you an expensive design
(for free) is looking for something to do. Strange indeed.
Mac N8TT
--
J. Mc Laughlin - Michigan USA
Home:

This is admirable.

Let me understand:

You mean that it takes weeks of constant work and a deep knowledge of
antenna theory and design to take an off-the-shelf NEC file (which you can
buy for a few bucks, and probably many are freely available) - to end up
with a half decent antenna?

If that is the case, then of course my expectations may be unrealistic.

But I was thinking that for someone who knew what they were doing, taking an
NEC file as a starting point and then applying adjustments to take into
account the actual construction details would be a few hours work. Because
antenna programs do all the calculations. You just need to know what you
are doing.

I would not want anyone spending much time on something, of course. I just
thought for someone who knew what they were doing it would a be a doddle.
Heck, the real design work has been done already, it's just a matter of a
few small adjustments. So I thought.

But if that is not the case, I stand corrected.

And if so, so I'd have no option but to do everything myself. Because that
would practically be unavoidable. I never thought this was the case.