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Place the transmitter on a flat surface with no other objects within 2 inches. This is important for convection
cooling, especially the right side during key down periods greater than 5 minutes - the enclosure will become
warm to the touch. If key down periods will exceed 30 minutes or the ambient temperature is above 80 degrees,
air needs to be blown over the top and right side of the enclosure or turn the power down to 3Wpep (no video).
Connect the red lead from the DC power jack to a good regulated 12 to 14 Vdc >2A power supply or battery
directly and the black lead to negative or ground. Longer leads or junction boxes with other gear could put noise
in the picture.
Connect a good low VSWR 70cm Antenna using low loss 50 Ohm coax to the antenna jack. Best not to use
adaptors, but strictly N plugs with 420 MHz and above.to minimize losses. If you have a RF power meter that is
rated for 70cm, you can put it in the antenna coax line for the initial VSWR and system tests.
Select the local ATV frequency from the 4 (ch 1 not used) available on the front panel channel switch. Make
contact with a close by ATVer on the 2 meter coordination and talk back frequency to make sure the frequency or
repeater is clear and have some one to comment on your tests. Watching yourself on another TV in the shack
can give false results from overload or multipath.
Flip the Power switch to on and the green LED will light if you connected to the power supply correctly. Flip the
XMIT/REC switch to XMIT and the green will go off (as well as the downconverter if connected) and the red LED
and RF output will come on in 2-3 seconds. Verify less than 10% reflected power within 15 seconds before further
operation. We set the Peak envelope power for 4.2 Watts at the lowest power channel with no video. If all is OK,
you can plug in the camera video, line and or mic audio and optional video monitor. Set the Mic and/or Line Audio
gain as you speak normally at normal distance up to the point that the red LED winks off, then slightly back down.
When the XMIT switch is on, you are still transmitting when the red LED winks off during audio over deviation
peaks. Have the local ATVer talk your antenna rotation in for best picture via two meter voice.
Please read the detailed information on each connector and control that follows in this manual.
REAR PANEL:
POWER INPUT JACK. A 4 pin plug 2 ft cable is provided for
connection to your source of +12 to14 Vdc and to a
downconverter. Currant draw is <2A in transmit. Pin 1 is DC
ground and a black wire. Pin 2 is + and red. A cable with a
coaxial plug on the end connects to pins 3 (-) and 4 (+) to
output to a downconverter in receive. Power coaxial plug is
center +. The TX70-5s works best from a well regulated
voltage source with leads no longer than necessary. The
transmitter is set up by us from a regulated 13.8 Vdc supply.
Do not exceed 15 Vdc input. In case the voltage is reversed,
there is a internal series diode to prevent damage to the
unit. 16 v zeners on the sound and T/R relay boards should
blow the internal 2A fuse if this voltage is exceeded.
Any ripple or noise on the DC line may be seen in the
transmitted video. For this reason, if a single large power
supply is used to power this and other equipment, all leads
must connect directly at the power supply terminals, not to
an external terminal block. If an external amp is added, it is
best to run it from its own separate power supply.
TX70-5s ATV Transmitter Quick Start
DOWNCONVERTER POWER. A 2 ft cable is supplied with
a 2.1 X 5.5 mm plug on the end to connect from this jack to
a TVC downconverter. DC power (center is +) is at this jack
when the XMIT / REC switch is in REC and open when in
XMIT.
2 AMP FUSE INSIDE. The TX70-5s itself draws about 1.5
amp in transmit, and .1 amp plus external downconverter in
receive - A 2.0 amp 3AG fuse should handle both.
EXT KEY JACK. Grounding the tip keys the transmitter.
This jack is in parallel with the front panel transmit/receive
(XMIT/REC) toggle switch and can be used to key the
transmitter from an external switch to ground or key an
amplifier as long as the amp is run from a 13.8V power supply.
50 OHM 70 CM ANTENNA. A UG21 type N plug is provided
to attatch to low loss .5" size 50Ω coax. Losses at 70 CM
are very high in transmission lines.
foam filled types such as Belden 8214, or semi rigid Belden
9913 or Times LMR400. Put the connector together properly,
or buy a ready made cable. The type N connector has good
moisture resistance and low loss at UHF but use two layers
of vinyl tape or Coax Seal on all outside connections to
prevent moisture contamination. The antenna and feed line
are the most important part of your ATV system, and therefore
the last item to just try and get by with.
2
We suggest using the
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