PSN-L Email List Message

Subject: Re: First time Lehman build
From: ted@..........
Date: Thu, 30 Dec 1999 13:40:53 -0500




Regarding the length, there's a choice to be made.  If you prefer (as I do)
that the magnet and coil be mounted on the base, you need a long base like
36-40" or so.  Lots of folks (including Lehman) just build a short base of
16" or so, let the boom hang over, and rest the coil on the floor.  I like
the longer base because you can get a finer adjustment of the level, also
the relationship of the magnet and coil doensn't change when you adjust the
leveling screws.  There are enough things to fiddle with without worrying
about that.  (This is a case when one infinity is definitely larger than
another, because both designs have an infinite number of ways to give you a
headache).

Regards, Ted Blank


BOB BARNS  on 12/30/99 01:04:46 PM

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Subject:  Re: First time Lehman build



Hi,
  I think that 1/2" or 3/4" thick aluminum base is gross overkill.  My
Lehman has a base 3/8" thick and is about 12" wide and 16" long.  I
think that this is plenty.

Bob Barns


Karl Cunningham wrote:
>
> Jim --
>
> Just to add a note to what Ted said...
>
> As Ted said, the base should be pretty thick.  One of the things about
> Lehmans is the need to adjust the leveling of the base once in a while.
> You will undoubtedly have leveling screws in the corners of the base
> nearest the mass.  It is extremely sensitive to even slight turning of
the
> leveling screws.  The sturdier the base the easier leveling will be, and
> the wider the base the finer the adjustment that can be made.
>
> You may think this is overkill, but I'd try to find at least 1/2" thick
> aluminum, preferably 3/4" thick or more.  And it should be at least 8 to
> 10" wide.  The wider the better.  If you have room, make it 12" wide.
>
> As Ted suggested, check surplus metal outlets for the aluminum plate.  If
> you can't find a piece the right size, they might cut it for you for a
few
> dollars more.
>
> Good luck on your project.  Be sure to post any questions you have to the
> list, and let us know of your progress.
>
> Karl Cunningham
> La Mesa, CA.
> PSN Station #40
> karlc@.......
>
> At 10:37 PM 12/29/1999 -0500, you wrote:
> >Gentlemen,
> >
> >My son and I are starting the process of building our first Lehman.  I
have
> >visited numerous PSN web pages,  and would like to thank everyone who
has
> >posted pictures and such relating to the construction.
> >
> >Would anyone out there care to supply me with just the basic dimensions
of
> >the frame, boom, and base.  I will be using Larry Cochrane's
electronics,
> >and would just like to get a little help so that we can get this project
off
> >the ground.
>
> _____________________________________________________________________
>
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Larry Cochrane <cochrane@..............>