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Re: Myers' BBQ Grill



Hi Pieter

The junked MMDS dipole antenna is supported on 1/4 WL supports.    The
measurments of the antenna are as follows:


Brass shim stock   .016 in thick
Brass shim width .2 in
Coax dielectric diameter    .275 in
Overal dipole length 2.525 in
One half of the dipole brass 1.020 in
length of the 1/4 WL stand off   1.1 in      From the end of the coax
shield to the inner edge of the dipole
The coax outer jacket is removed to show .3 in  of shield 
The center of the coax extends above the coax shield    1.060 in
The coax is RG-8 
The center of the dipole is seperated by the .275 in width of the coax
dielectric 
The entire antenna is encased in a plastic housing which seal the outer
coax jacket.
The dipole is made by bending the shim stock so that the length of the
1/4 WL stand off and the length of one half the dipole is integral.

There is a splash plate which is made from a 4 inch wide aluminum .050
thick 
There is a flat section down the middle 1/2 in wide
At the edge of the 1/2 in section the plate is bent at a 25 degree angle
toward the dish 
The bent  section measures 4 in by 1- 3/4 in 
Two screws through the splash plate into the plastic dipole housing hold
the splash plate an undetermined distance from the dipole.       I will
estimate the distance to be 1-1/8 in.
Some of these splash plates have slots length wise through the 4 X 1-3/4
surface of the splash plate 
the splash plate is aligned with the grill in the dish face.

The above was taken with calipers.




If you have additional questions feel free to ask

Joe  K0VTY
=================================
On Mon, 14 May 2001 12:39:23 -0400 "Pieter Ibelings"
<elpieter@hotmail.com> writes:
> Can someone give me the details of the stub. I need to know what coax 
> it is
> (ut 141?) and the lengh. I will simulate it and suggest things that 
> need to
> be done if any.
> 
> Pieter
> 
> ----- Original Message -----
> From: "Greg Dolkas" <greg@core.rose.hp.com>
> To: <amsat-bb@AMSAT.Org>
> Sent: Monday, May 14, 2001 11:51
> Subject: Re: [amsat-bb] Myers' BBQ Grill
> 
> 
> > >
> > > Further to my query regarding the short circuit at the 
> connector.  I
> have
> > > opened up the housing and discovered the reason for the short.   
> There
> is a
> > > quarter wave stub at the centre of the dipole.   The centre of 
> the coax
> is
> > > soldered to one side of the dipole and the braid at the shorted 
> end of
> the
> > > stub.  Quite obviously this is a matching technique and the 
> antenna
> should
> > > be fine at RF.
> >
> > "Fine", of course, is a relative term.  The stub was undoubtedly 
> designed
> > for around 2.6 ghz.  Can anybody calculate how much is lost when 
> it is
> > run at 2.4 ghz?  I am wondering if this is a factor in why I'm 
> having
> > such poor reception with my Lance BBQ grill and feed.  At DC it 
> measures
> > about 1 ohm, so the construction might be similar to yours.
> >
> > My guess is that it probably isn't enough to notice, but I want to 
> look
> > at everything.
> >
> > Thanks,
> >
> > Greg.
> > ----
> > Via the amsat-bb mailing list at AMSAT.ORG courtesy of AMSAT-NA.
> > To unsubscribe, send "unsubscribe amsat-bb" to 
> Majordomo@amsat.org
> >
> ----
> Via the amsat-bb mailing list at AMSAT.ORG courtesy of AMSAT-NA.
> To unsubscribe, send "unsubscribe amsat-bb" to Majordomo@amsat.org
> 
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