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


Hmmm, Mac made sense to me. He always does, come to think of it.

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.

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.

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

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
:-)

Richard wrote:

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!

There are half a jillion designs already out there. Also in books. All
designs can scaled to any other frequency. IE: any 2 meter VHF antenna
design can be easily scaled to 160 mhz. Why the rigid construction
requirements?
If you are scaling a design to another freq, you should also scale the
element dia. Luckily, there should be no need to change element diameter
for a rescaled 2m antenna, as it's already close enough. I once built a
marine band 4 element yagi from a thin copper tube as a boom, and
coathanger wire soldered to the boom as the elements. Not the greatest
materials, and it eventually rusted, but I could hear stuff that didn't
exist on verticals. I'm in Houston, and was listening to marine traffic
out towards Galveston, and the gulf. 50-60 plus miles easy... If you
have NBS designs, what are you waiting for? Those spacings are quite
good enough. They do lean towards max gain vs f/b, but you don't need
super f/b with what you are doing. So a NBS design should be fine. "the
f/b is still about 10 db" Thats what I used. My 6m beam is also a NBS
yagi. All my homebrew yagi's use a driven element grounded to the boom.
Also, I use gamma or T matches, etc...I rarely use a split driven
element insulated from the boom. It's more work, and I'm lazy...Only my
store bought "I didn't pay for it" HF beam is built that way. MK

--
http://web.wt.net/~nm5k

"Mark Keith" wrote in message ...

There are half a jillion designs already out there. Also in books. All
designs can scaled to any other frequency. IE: any 2 meter VHF antenna
design can be easily scaled to 160 mhz. Why the rigid construction
requirements?
If you are scaling a design to another freq, you should also scale the
element dia. Luckily, there should be no need to change element diameter
for a rescaled 2m antenna, as it's already close enough. I once built a
marine band 4 element yagi from a thin copper tube as a boom, and
coathanger wire soldered to the boom as the elements. Not the greatest
materials, and it eventually rusted, but I could hear stuff that didn't
exist on verticals. I'm in Houston, and was listening to marine traffic
out towards Galveston, and the gulf. 50-60 plus miles easy... If you
have NBS designs, what are you waiting for? Those spacings are quite
good enough. They do lean towards max gain vs f/b, but you don't need
super f/b with what you are doing. So a NBS design should be fine. "the
f/b is still about 10 db" Thats what I used. My 6m beam is also a NBS
yagi. All my homebrew yagi's use a driven element grounded to the boom.
Also, I use gamma or T matches, etc...I rarely use a split driven
element insulated from the boom. It's more work, and I'm lazy...Only my
store bought "I didn't pay for it" HF beam is built that way. MK

--
http://web.wt.net/~nm5k

Mark

If I am prepared to go with other peoples electrical and mechanical designs
then there is no doubt my task ought to be easy peasy. And as you say there
are zillions of designs out there already.There is a heck of a lot of sense
in taking that approach. :c)

It's perhaps unfortunate that I was started off by being given a model to
run in a program. This may have complicated the approch uneccessarily and
taken me away from what was the more sensible approach.

So obtaining software models and messing with antenna programs is perhaps
rather a redundant exercise.

Thanks for driving that home to me.

Rich