Richard wrote:
Richard wrote:
All the vertical part of the antenna is made of
aluminum tubing. B is a short peice of fatter
aluminum tubing than either A or C. C
electrically connects with A, so I presume
there is a coil within aluminium tube B. Tube
B, at the bottom, looks rivited to tube C.
So I'm saying B is like:
| | A
_____|__|_____
| | | |
|____|__|_____|
| | | |
| x |
| x |
| x | B
| x |
| x |
| x |
| x |
|____|__|_____|
| | |-----| Rivet
|____| |_____|
| | C
| |
There are insulated collarsat both ends of B.
X represents assumed coil connecting A to C.
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Okay I removed tube B and made measurements. Here are
the details that ought to allow someone to do
calculations for the vertical part of the antenna:
| |-------------------
| | |
| | |
| | |
| | |
| | p 19" (48 Cm)
| | A |
_____|__|_____ --- |
| | | | | |
| | | | | |
| | | | q 1.25" |
|____|__|_____| | (3Cm) |
| | | |------------|
| x |
| x |
| x | B
| x |
| x |
| x |
| x |
| | | |------------------
| | | | | |
|____|__|_____| r 1" (2,5 Cm) |
| | | | | |
| | |ooooo|--- Rivet |
|____| |_____| connecting |
| | tube B |
| | to tube C |
| | |
| | s 60" (153 Cm)
| | C |
| | |
| | |
| | |
| |------------------------
^ Feedpoint
Tube B is a 4"(10 Cm) long tube.
Tube B connects to tube C 1" (2,5 Cm)from the
top of tube C. Tube B in fact shrouds the top
1" of tube C. Top of tube C connects to the
bottom end of a coil shown by x's. The top end
of the coil connects to tube A which is 19"
(48 Cm)long.The top part of tube B shrouds
over the bottom part of tube A by 1.25"(3Cm).
I got the inductance of the coil to be appx 3uH.
Length: 24mm
O.D. coil: 23mm
Turns:13
Spacing: Closewound
Wire diameter:1.5mm
So I suppose next task is to calcuate
the resonant frequency of the vertical part
of the antenna. Thing is,is it meant to
be a quarter wave half wave 5/8th wave or
what. The feedpoint impedance I reckon will
be 50 or 75 Ohms. I don't know how to calculate
this.
The 3 radials are 28" (71 Cm)long, but appear
to have small coils at the beginning of the
radials. The coils on two of the radials look
the same, and the coil on the third radial looks
about twice as long as the other two coils. The
smaller coil inductances seems to be very
approximately 0.330 uH, so the inductance of the
larger coil on the third radial is about 0.660 uH.
Smaller radial coils data:
Length: 7.5mm
O.D. of coil: 12mm
Turns: 5
Spacing: Closewound
Wire Diameter: 1.5mm
larger radial coil data:
Length: 7.5mm
O.D. of coil: 24mm
Turns: 5
Spacing: Closewound
Wire Diameter: 1.5mm
Perhaps now these data might help figure
out what frequency this antenna is for.I hope.
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This post is perfect for this group. Now that I've posted all the necessary
the data it ought to be fathomable..
Reg, you must be able to work this antenna out.
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