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To put together a
TV station you will need this stuff:
A VCR or
Camcorder with video or RF outputs
A Ham Radio
6-meter Band Linear amplifier
(This boosts the RF signal from the VCR
for broadcasting)
(The Linear Amp should have a bandwidth
of 6 MHz for best results)
A cable television RF distribution
amplifier may also be used.
Coaxial cable
with UHF connectors
(Connects the Linear Amp to the Antenna)
A cable-TV patch
cable with an F-connector and a UHF connector
(To connect the RF signal to the Linear
Amp)
(F-connectors are the small ones used
with cable TV)
(UHF connectors are the large ones used
for Ham Radio)
If your VCR does
not have RF outputs:
An external RF modulator (converts video
to channel 3,6,12 etc.)
a cable with RCA connectors (a standard
stereo cord is ok)
A 6-meter Ham
radio antenna.
If you do not
have a pre-made 6-meter antenna:
About 20 feet of strong wire
3 ceramic antenna insulators
another UHF connector
Likely places to get the linear amplifier,
connectors and cables is a
Ham Radio
swapmeet, a Ham club newsletter's classified ads, a Buy-Sell-Trade
paper like The
Recycler, or at a store specializing in Ham gear.
RF modulators are
available at specialty video stores, or major VCR dealers.
Setting Up the
Transmitter:
Using a VCR with RF out:
[VCR/RF]F----------------------------U[Linear
Amp]U------------U[Antenna]
weak RF Power RF
Using an External RF Modulator:
[VCR]R-------R[RF
Modulator]---------U[Linear Amp]U------------U[Antenna]
video weak RF Power RF
Diagram Symbols:
U UHF-connectors (Ham radio)
F F-connectors
(cable TV)
R RCA connectors (stereos)
--- coax, cables, wires
[] devices (name of device in brackets)
<I> ceramic insulator (the kind with a hole at
each end)
Building The
Dipole Antenna:
wire wire
<I>---------------------+<I>+----------------------<I>
| |
Short coax | |
[U] UHF connector
The antenna is
set up much like a clothesline with the wires tethered
straight out
horizontally. The outer insulators are used to isolate the
antenna from the
tether lines, which should be rope or nylon cords
for good results.
The inner insulator isolates a gap between the two
long wires of the
antenna.
The length of the
wires used for the antenna is critical.
Look up the
length in feet for the channel you want to use in the
table below &
make each of the two long wires that length.
As a rule of
thumb, a wire half-wave antenna's length in feet is equal to
468 divided by the
frequency in MHz.
****************************************
VHF Television Channel Data
----------------------------------------
TV
MHz ---carrier--- antenna
channel
range video sound
lengths
-------
----- ----- -----
-------
2
54-60 55.25 59.75
8.47ft
3
60-66 61.25 65.75
7.64ft
4
66-72 67.25 71.75
6.95ft
5
76-82 77.25 81.75
6.05ft
6
82-88 83.25 87.75
5.62ft
7
174-180 175.25 179.75
2.67ft
8
180-186 181.25 185.75
2.58ft
9
186-192 187.25 191.75
2.49ft
10
192-198 193.25 197.75
2.42ft
11
198-204 199.25 193.75
2.34ft
12
204-210 205.25 209.75
2.28ft
13
210-216 211.25 215.75
2.21ft
(All frequencies in MHz)
(Lengths are for half-wave antennas)
****************************************
For Further
information: Look in the ARRL Handbook published by the American
Radio Relay
League for detailed plans & theory for antennas, transmitters &
linear
amplifiers. The info in that book can be used for setting up an
underground AM or
FM radio station.
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