"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 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.

I'm going to look at Enzec help files, I suspect I can do my own work
starting with a model. Producing full constructional notes should not be
difficult.

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

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.


I asked a reasonable question, and did not expect a sarcastic response.
Please: why is there a need, or an interest, to "eavesdrop" (using your
description) on the marine band with a high gain unidirectional antenna?

73,
Chip N1IR

There shall be some kind of balun.

Please, please!

====================================

Why?

What's the percentage current unbalance on the balanced line when there's a
450-ohm to 50-ohm, balanced to unbalanced junction without a balun?

What percentage current unbalance does a typical choke balun reduce
unbalance to -

- - - - with a receiving antenna ?

- - - - with a transmitting antenna ?

if there's any difference.
---
Reg

Reg Edwards wrote:
What's the percentage current unbalance on the balanced line when there's a
450-ohm to 50-ohm, balanced to unbalanced junction without a balun?

You didn't give enough information for anyone to provide a valid answer,
Reg. What is the impedance from the junction looking back toward system
ground? If it is three ohms, a balun is necessary. If it is 300 ohms,
you can probably get by without a balun.
--
73, Cecil http://www.qsl.net/w5dxp



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"Cecil Moore" wrote Reg Edwards wrote:
What's the percentage current unbalance on the balanced line when
there's a
450-ohm to 50-ohm, balanced to unbalanced junction without a balun?

You didn't give enough information for anyone to provide a valid answer,
Reg. What is the impedance from the junction looking back toward system
ground? If it is three ohms, a balun is necessary. If it is 300 ohms,
you can probably get by without a balun.

OK, so it's 3 ohms. Wot's the percentage unbalance ?
Just a number is required.

If it's 300 ohms. Wot's the percentage unbalance ?
Just another number is required.

What are the odds on you providing answers ?
----
Reg

"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).

Reg Edwards wrote:
"Cecil Moore" wrote Reg Edwards wrote:
You didn't give enough information for anyone to provide a valid answer,
Reg. What is the impedance from the junction looking back toward system
ground? If it is three ohms, a balun is necessary. If it is 300 ohms,
you can probably get by without a balun.

OK, so it's 3 ohms. Wot's the percentage unbalance ?
Just a number is required.

How about Ohm's law? 3 ohms in parallel with ??? ohms.
I forgot to ask what is the impedance looking in the
direction of the load.

If it's 300 ohms. Wot's the percentage unbalance ?
Just another number is required.

How about Ohm's law? 300 ohms in parallel with ??? ohms.
--
73, Cecil http://www.qsl.net/w5dxp



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On Sat, 05 Jun 2004 15:09:55 -0500, Cecil Moore
wrote:
I forgot to ask
:-)