[This post is sent again in plain text (cannot avoid that). I've
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ay need to adjust your viewing font (ToolsOptionsReadFonts)
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I've no real experience of putting up antennas on the chimney
of a house.

Obviously, I must not overload the chimney breast.

I'm thinking about putting up the following:


_______ Discone
/ | \
__ / || \
A |
__ ___|x___ 5 ele.2m yagi
|
B | |
__ |x| 5 ele. marine yagi
| |
C |
| |
__ |x| 5 ele. FM yagi.
| |
D |
|
__ |
/ \ Rotator
/___\
|
| ______
| | | Chimney
| | |
| | |

I'm wondering about the spacings, A, B, C, and D.

A, spacing between bottom of the discone and the boom of 2 m yagi.

B, spacing between boom of 2m yagi and boom of marine band yagi.

C, spacing between boom of marine band yagi and boom of FM yagi.

D, spacing between boom of FM yago and top of rotator.

As for the mast, I'm thinking what about 1.5" steel tube.

As for rotator. No idea what model I'd need.

Any thoughts? Am I trying to be too ambitious? I could
leave out the marine yagi if I had to.

Thanks.

Rich.

On Tue, 17 Feb 2004 22:41:16 -0000, "Richard"
wrote:
[This post is sent again in plain text (cannot avoid that). I've
used a monospaced font type, "courier new", font size, "smaller"
to view the page on my PC. To correctly view the ASCII art, you
ay need to adjust your viewing font (ToolsOptionsReadFonts)
to: Proportional Font: "Courier new" Font size: "smaller".]


Hi Richard,

It may look good to you, but for many it remains sloppy.

The convention of ASCII-Doodles is to employ fixed pitch fonts. This
is available to everyone.

A, spacing between bottom of the discone and the boom of 2 m yagi.
0.5M to 1M
B, spacing between boom of 2m yagi and boom of marine band yagi.
0.5M to 1M
C, spacing between boom of marine band yagi and boom of FM yagi.
0.5M to 1M
D, spacing between boom of FM yago and top of rotator.
0.5M

Proximity is more likely to disturb the depth of nulls than to rob
gain. Proximity will also pull resonant frequency. Recommendations
will run the gamut where a purist would demand 1 to 5 wavelengths.
Practice often accepts much less when offset by sweat-equity (more
tuning and trimming on your part).

Don't forget guy wires to preserve the mortar (its not the brick that
breaks); and don't forget to break up the guys to prevent their
resonance effects (or use non-conductive guys).

73's
Richard Clark, KB7QHC

Hi,

One thing I have not seen in previous replies,

If you use a band clamp to attach the mast to the chimney,
water can get behind the metal band and when it freezes, cause
damage to the brick.

In warm weather, the bricks expand and the metal bands
damage the bricks.

I'm not an engineer but another post recommended to use guy
wires so to reduce windload off the chimney.

I don't believe this will reduce windload at all, the guys will
be attached to the mast only and not the actual antenna so
no reduction in windload.

Best to avoid using the chimney and attach the mast to the house
at the eave using long bolts and nuts attached to some pressure treated
(and painted) 2x4's on outside and inside the attic. stronger and
you don't have to worry about the coax getting too hot from the heat
of the chimney exhaust.

mick

"Richard Clark" wrote in message
...
On Tue, 17 Feb 2004 22:41:16 -0000, "Richard"
wrote:
[This post is sent again in plain text (cannot avoid that). I've
used a monospaced font type, "courier new", font size, "smaller"
to view the page on my PC. To correctly view the ASCII art, you
ay need to adjust your viewing font (ToolsOptionsReadFonts)
to: Proportional Font: "Courier new" Font size: "smaller".]


Hi Richard,

It may look good to you, but for many it remains sloppy.

The convention of ASCII-Doodles is to employ fixed pitch fonts. This
is available to everyone.

Hi.

I have used fixed pitch on the second post. Courier new is fixed
pitch/monospaced.

I beleive the viewer though has to change the veiwing font to courier new.