"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.

"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.

"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:


I bought some "models" from Mr Cebik.

This is what he says in his notes:

" Although many of the designs may be directly built from the models in this
collection, the models themselves are for study purposes. Perfecting the
design to a level that permits construction of an antenna that is both
electrically and mechanically sound is your responsibility.

L. B. Cebik, W4RNL"

This is my problem and what I was asking for. I can mess around with the
models quite freely, but perfecting the design to a level that is both
electrically and mechanically sound is right now beyond me. What you are
saying is that this task is such a huge one and requires great skill. Not
easy then for your regular Joe ham to do much with the models in a practical
way. He/she has to become something of an antenna buff for that to
transpire. And because the task is so demanding, no antenna buff would ever
consider producing an actual contstruction design for anyone, apart from
him/herself maybe. And then he/she might condescend to allow others to
copy his/her design.

Richard wrote:
I can mess around with the models quite freely, but perfecting the
design to a level that is both electrically and mechanically sound is
right now beyond me. What you are saying is that this task is such a
huge one and requires great skill. Not easy then for your regular Joe
ham to do much with the models in a practical way. He/she has to
become something of an antenna buff for that to transpire.

A few years ago, if any amateur got involved in the esoteric art of
antenna modelling, it was because he or she was *already* an advanced
antenna buff, with lots of hands-on experience of making antennas work.

After learning about modelling, with all its tricks and traps, the next
challenge was to learn how to translate the models back into workable
hardware. But at least that was building a bridge between two solid
foundations.

Now, it's becoming the other way around - the modelling is more
accessible than the hands-on experience. Without that practical
experience, translating a model into reality is like building a bridge
to nowhere.

It isn't "something for someone [else] to do." Someone else can run
models for you, but only the person with the hardware in their hands can
work out how to build the real thing.

However, about the worst you can do is cut the elements to the wrong
lengths. The program on my website (see earlier posting) will help, and
you should also read all three of the links from that same page.

If you come back with a question more like: "I've tried to work out how
to do this. Here are the model dimensions, here are my cutting
dimensions, and here's why. Does this look reasonable?" then I'm sure
you'll get a lot more help.


(Coffee mug's empty... back to the window-frames.)


--
73 from Ian G3SEK 'In Practice' columnist for RadCom (RSGB)
http://www.ifwtech.co.uk/g3sek

"Ian White, G3SEK" wrote in message
...
Richard wrote:
I can mess around with the models quite freely, but perfecting the
design to a level that is both electrically and mechanically sound is
right now beyond me. What you are saying is that this task is such a
huge one and requires great skill. Not easy then for your regular Joe
ham to do much with the models in a practical way. He/she has to
become something of an antenna buff for that to transpire.

A few years ago, if any amateur got involved in the esoteric art of
antenna modelling, it was because he or she was *already* an advanced
antenna buff, with lots of hands-on experience of making antennas work.

After learning about modelling, with all its tricks and traps, the next
challenge was to learn how to translate the models back into workable
hardware. But at least that was building a bridge between two solid
foundations.

Now, it's becoming the other way around - the modelling is more
accessible than the hands-on experience. Without that practical
experience, translating a model into reality is like building a bridge
to nowhere.

It isn't "something for someone [else] to do." Someone else can run
models for you, but only the person with the hardware in their hands can
work out how to build the real thing.

However, about the worst you can do is cut the elements to the wrong
lengths. The program on my website (see earlier posting) will help, and
you should also read all three of the links from that same page.

If you come back with a question more like: "I've tried to work out how
to do this. Here are the model dimensions, here are my cutting
dimensions, and here's why. Does this look reasonable?" then I'm sure
you'll get a lot more help.


(Coffee mug's empty... back to the window-frames.)

Okay, well, I'll do some more work on it and come back.

When I made my post, I'm not just thinking of myself, others too might have
liked to see full constructional notes. That's part of the circumstances
(for those (not you Ian) who perhaps cannot have comprehended that).

"Richard" wrote in message ...
"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:


I bought some "models" from Mr Cebik.

This is what he says in his notes:

" Although many of the designs may be directly built from the models in this
collection, the models themselves are for study purposes. Perfecting the
design to a level that permits construction of an antenna that is both
electrically and mechanically sound is your responsibility.

L. B. Cebik, W4RNL"

This is my problem and what I was asking for. I can mess around with the
models quite freely, but perfecting the design to a level that is both
electrically and mechanically sound is right now beyond me. What you are
saying is that this task is such a huge one and requires great skill. Not
easy then for your regular Joe ham to do much with the models in a practical
way. He/she has to become something of an antenna buff for that to
transpire. And because the task is so demanding, no antenna buff would ever
consider producing an actual contstruction design for anyone, apart from
him/herself maybe. And then he/she might condescend to allow others to
copy his/her design.

Pore deprived thing.

You study some of the mountain of illustrated artcles in the ham
literature which show how others have sucessfully put VHF Yagis
together to get an education on the various "basement engineering"
practical mechanicals they came up with.

You run the model based on the materials you have available and the
construction scheme you have chosen.

You build it. You test it. You tweak it. You put it up again and go
SWLing on
162 Mhz.

No, you don't have to be an "antenna buff" to do any of it these days.

But if you build your own you do have to get off your butt and put a
bit of your own mental effort into the matter. Don't hold your breath
while hoping that somebody around here will save you from the
butt-lift maneuver just because you don't wanna do it yourself.

w3rv

Dear J. McLaughlin, self proclaimed newsgroup cop. If you don't know
the answer to his question, why did you bother to answer him? Just
wanted to "dig" on him a bit because he didn't post his call? You
posted yours and you still came off sounding like a pompous know it
all ass.
Or was that your intention?



On Sat, 5 Jun 2004 09:59:36 -0400, "J. McLaughlin"
wrote:

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