Measuring Surface Flatness (was "Cabinet Grade Particle Board")

[Bill Glaze]

Ron:
The Chrome Monokote parallels what we were told about using aluminum 
colored Butyrate dope, years ago.  I had pretty much forgotten it.
Interestingly, (at least to me) was a Bob Godfrey Laser 200 I bought 
used several years ago from a well known modeler.  I put in my radio, 
and, after noticing several antenna positions that were apparently used 
by the former owner, I selected the easiest location.  Fortunately, 
before flying, I did my usual range check. Instead of the 60+ yards I 
usually got, (antenna colllapsed) I couldn't get even 20 yards.  The 
other pre-located positions showed the same results.  So, with little to 
lose, I moved the antenna outside.  While not as pretty, the 60 yards 
plus returned.  I subsequejtly flew the airplane; haven't had any radio 
problems at all.  I asked the previous owner about the situation; he 
said: "Well, I did have a few glitches now and again."  I'll bet!  The 
covering?  Metallic Blue Monokote.  Does this prove anything?  Probably 
not.  But, I'll play it safe, and range check any way.  BTW:  All my 
pattern stuff has always had internal antennas; no problem.
Bill Glaze

Ron Van Putte wrote:

>
>
> On Nov 23, 2004, at 3:31 PM, Keith Black wrote:
>
>     In other words, if you built your fuse out of this material you'd
>     probably want to run your antenna externally. ;-)
>
>
> I can remember when some self-styled RF experts were warning of the 
> danger of using chrome Monokote, which contains no metal) when running 
> the antenna inside fuselages. <BG>
>
> Ron Van Putte
>
>     ----- Original Message -----
>
>     From: Bob Richards
>     To: discussion at nsrca.org
>     Sent: Tuesday, November 23, 2004 2:59 PM
>     Subject: Re: Measuring Surface Flatness (was "Cabinet Grade
>     Particle Board")
>
>     John,
>      
>     I disagree. The definition of a "Faraday CAGE", which is what Bill
>     said, is a completely conductive sealed enclosure.
>      
>     Also, the edges don't have to be fully bonded together for RF
>     protection. They can be stitched together at intervals depending
>     on how high in frequency you want attenuation. The closer the
>     spacing, the higher the cutoff frequency. Obviously, if you want
>     cutoff up into the gigahertz range, you pretty much need a
>     continuous bond.
>      
>     http://www.boltlightningprotection.com/Elemental_Faraday_Cage.htm
>      
>     http://en.wikipedia.org/wiki/Faraday_cage
>      
>     Bob.
>
>
>     John Ferrell <johnferrell at earthlink.net> wrote:
>     Sorry to get picky, but a Faraday shield is not an electromagnetic
>     field, it is an electrostatic shield.
>      
>     An rf tight room needs the edges fully bonded together and a
>     Faraday shield requires that they be insulated.
>      
>     I think everyone knows what is being said, but I felt obliged to
>     add the detail.
>      
>     John Ferrell  
>     My Competition is not my enemy!
>     http://DixieNC.US
>     ----- Original Message -----
>     From: Bob Richards
>     To: discussion at nsrca.org
>     Sent: Monday, November 22, 2004 1:06 PM
>     Subject: Re: Measuring Surface Flatness (was "Cabinet Grade
>     Particle Board")
>
>     That's what it is. No RF gets in or out. Something like 110dB
>     attenuation.
>      
>     Bob.
>
>
>     Bill Glaze <billglaze at triad.rr.com> wrote:
>     Bob:
>     Do I recall when such a room as you describe was known as a
>     "Faraday Cage?"  Or am I having one of RvP's "Senior Moments?" 
>     (No offense, Ron! O:-) )
>     Bill Glaze
>
>
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