PROCASTER AMTX100 AM Transmitter
Installation and Operation
(PRELIMINARY)
Installation
PROCASTER™ contents
• PROCASTER™ transmitter module
• Studio interface module
• Antenna tubes (3 pieces)
• Hardware
• AC wall adapter
• Assembly/installation instructions
Changes or modifications not expressly approved by ChezRadio could void user's
authority to operate the equipment.
SAFETY WARNING
TO PREVENT ELECTROCUTION ALWAYS BE AWARE OF NEARBY ELECTRICAL POWER
WIRING AND MOUNT THE ANTENNA FAR ENOUGH AWAY SUCH THAT IF THE ANTENNA
FELL DOWN, THERE WOULD BE NO CHANCE OF CONTACT.
Before starting your installation, consider the following carefully:
• Is the chosen frequency clear?
• Are there nearby obstructions such as buildings, trees and power lines etc?
• Where are you going to mount the transmitter?
• Where are you going to ground it?
• What range are you expecting to get?
For a successful installation, follow these steps...
Page 1 of 9
PROCASTER AMTX100 AM Transmitter
Installation and Operation
Step 1. Choose a Quiet Channel
Drive around your chosen broadcast area and listen for clear channels. Note: car radios are
usually more sensitive than portables, so that should be considered too. If you want to broadcast
at night, you would have to check if the channel is clear then. It's more difficult to broadcast at
night because changes in the ionosphere cause signals from higher-powered radio stations
to reach your broadcast area; so bear that in mind. Try to choose one of the highest 42 channels
available for the PROCASTER™ by setting the option switches accordingly. The higher the
frequency, the better the range because of the restrictive short antenna length.
Step 2. Install Location
Higher mounted antennas usually result in better range. The PROCASTER™ mounting bracket is
intended for mounting on a flat vertical surface. Optional kit # XXXXX allows pole mounting. Make
sure you can access the transmitter for tuning once it is in its final position. A good height above
earth ground is about 25 feet. The roof of a 2-storey building is a good choice.
Step 3. Assemble Antenna
Three aluminum tubes (large 5/8", medium 1/2" and small 3/8") are assembled together to form a
103 inch antenna. These sections are held together using 2 stainless steel pipe clamps.
• Join the large tube to the medium tube
o slide a pipe clamp over the mid-point of the slotted end of the large tube
o insert the medium tube into the large tube lining up the black dot
o tighten pipe clamp snugly using a 1/4" nut driver
• Join the small tube to the medium tube
o slide a pipe clamp over the mid-point of the slotted end of the medium tube
o insert the small tube into the medium tube lining up the black dot
o tighten pipe clamp snugly using a 1/4" nut driver
• Fasten the assembled mast to the transmitter using (2) #10 lock-washers and (2)
locknuts - refer to E
o Use a screwdriver to prevent the bolt from turning while tightening the nuts - refer
to F
o Tighten snugly (don't over-tighten)
• Antenna assembly is now complete
Step 4. Mount External Transmitter
In all mounting cases, ensure you can reach the unit for tuning once installed!
Direct wall mounting
Mount the PROCASTER™ directly to a flat vertical surface using the 4 holes in the case
mounting plate. Make sure that there is sufficient space between the antenna mast and the rear
wall such that snow/ice does not cause a short.
(antenna assembly pics)
(direct on wall)
Page 2 of 9
PROCASTER AMTX100 AM Transmitter
Installation and Operation
Direct wall mounting with standoff brackets
Use Radio Shack 4 inch Antenna Mast Wall Mount kit catalog # 15-883 to hold the
PROCASTER™ further away from the wall.
(direct on wall with brackets)
Pole mounting
For pole mounting use a pair of 2 inch spacing U-bolts with formed curved backing plates – like
the ones in the following picture. The backing plate prevents the case mounting areas from
bending when tightening onto the pole and makes for a more secure installation.
(pole mounting)
Step 5. Install Ground
Connect the copper grounding lug shown below to a suitable ground.
(grounding lug)
Good grounding is extremely important for optimum antenna performance and is required for safe
operation of the lightning protection circuitry. Typical grounds include:
• Copper clad steel grounding rod at least 8 ft into earth ground
• Water pipe ground
• Radial ground system
• Metal roof
Warning: FCC rules (47 part 15.219) state:” the total length of the transmission line, antenna and
ground lead (if used) shall not exceed 3 meters.” [3 meters = 118 inches]
The PROCASTER™ has an attached 103 inch antenna measured from its tip to the lower
mounting bolt which is the connection of the transmitter output. It has no transmission line. A 15
inch maximum ground lead is allowed from the grounding lug to a massive ground.
Step 6. Connect Power and Audio Wiring
The PROCASTER™ connects to the studio interface with 4 conductor CAT3 wire. Because the
audio is balanced and the power consumption is low, several hundred feet of wire can be used
without issue. Proceed as follows:
• Open the PROCASTER™ cover by loosening the 3 cover clamps
• Insert 4 conductor CAT3 wire through liquid-tight grommet on the underside
• Connect:
o RED: +12V
o GREEN: 0V
o YELLOW: AUD +
Page 3 of 9
PROCASTER AMTX100 AM Transmitter
Installation and Operation
o BLACK: AUD -
• Tighten nut on liquid-tight grommet
(wiring pic)
Step 7. Connect to indoor Studio Interface Module
Bring the 4 conductor CAT3 cable into the studio area. Proceed as follows:
• Remove the 4 rubber feet from the studio interface enclosure
• Slide off the cover
• Pass the 4 conductor CAT3 cable through the rear bushing
• Connect:
o RED: +12V
o GREEN: 0V
o YELLOW: AUD +
o BLACK: AUD -
(rear of studio interface)
Step 8. Connect an audio source
The PROCASTER™ is fitted with a universal 3.5mm stereo input jack similar to I-pod™ and
modern car audio equipment. It has been designed to accept stereo left and right audio channels
and mixes them into a mono signal.
(front of studio interface)
The built-in audio processor has a fairly wide accommodation range and will automatically adjust
audio level for optimum sound quality. In addition there is an input audio level adjustment control
(normally set at mid-point) accessible through the front panel using a small jewellers screwdriver.
The audio level can be set from approximately 200mV to 3V which will accommodate most audio
devices.
Page 4 of 9
PROCASTER AMTX100 AM Transmitter
Installation and Operation
Step 9. Power Up the Procaster ™
Connect the AC wall adapter.
Step 10. Choose Channel Frequency
To choose the desired broadcast channel, refer to the Option Switch section. Note: the option
switch also allows additional settings to be made.
Step 11. Tune Antenna
Once the broadcast channel is set, turn the antenna tuning capacitor using a small bladed
screwdriver until a maximum reading is seen on the tuning meter. Make sure to stand clear of the
antenna as body capacitance will affect tuning. If the reading is not "sharp" and strong, re-check
your ground connection.
(tuning)
Antenna tuning is now complete. (Now that was easy!)
Step 12. Final Checkout & Adjustments
Check your sound level and range by listening on a radio. The broadcast signal should be clear
and strong when closer to the transmitter, with more noise heard the further you move away.
The built-in audio processor is what makes the PROCASTER™ sound like a big station. If you
want to use your own external audio processing equipment, the PROCASTER™ audio processor
can be disabled by changing the option switches.
The PROCASTER™ audio processor can be adjusted to suit personal preferences as follows:
Compression: Turning the compression control CW boosts quieter parts of the audio to be
more equal to the louder parts. This makes the overall audio louder resulting in a stronger signal
and greater range. The tradeoff is the subjective audio quality depending on the level of
compression.
Modulation Depth: Turning the modulation depth control CW increases the audio
modulation level of the AM signal.
Limiting: Limiting is automatic to prevent sideband 'splatter' and both the above adjustments
have no affect on the 'hard limiter' built into the audio processor.
Congratulations! You have set up your broadcast station.
Page 5 of 9
PROCASTER AMTX100 AM Transmitter
Installation and Operation
Specifications
Outdoor Transmitter Module
Modulation scheme AM
Harmonic suppression >30dB
100mW input power control
Frequency selection 42 channel PLL
Frequency range 1290kHz to 1700kHz
Antenna tuning manual adjust with meter
Treble boost option yes
Built-in audio processor
(may be disabled)
Audio input Balanced transformerless
Frequency response 20Hz to 20kHz +/- 3dB
Input voltage 12VDC 60mA
Enclosure NEMA 4X
Mounting 4 holes (2 in x 6.31 in)
Antenna 103 in, 3-section, aluminum
Approvals
Weight 6lb
Lightning protection 350V 1ns
ESD protection Audio and power
Connection to Studio Control 4 conductor CAT3
Automatic self-regulating
Compression control
Modulation depth control
Fast/slow release (selectable)
FCC Part 15.219
Industry Canada RSS-210
Indoor Studio Module
Audio input 3.5mm stereo jack
Input mixer Mixes left and right audio
Audio level adjust 200mV to 3V
Power input (switch selectable) 12VAC or 12VDC
Audio output Balanced transformerless
Weight 0.5 lb
ESD protection Audio and power
Connection to External Transmitter 4 conductor CAT3
Page 6 of 9
PROCASTER AMTX100 AM Transmitter
Installation and Operation
Option Switches
The function of the 10 position switch located in the PROCASTER™ is as follows:
• Switches S1 - S6 allow selection of 1 of 42 broadcast channels
• Switch S7 selects 1 of 2 audio processor response rates (music or voice)
• Switches 8 and 9 turns the audio processor on or off (when external processing is used)
• Switch 10 turns on the treble boost
(switch)
Miscellaneous Functions
S7 ON
S7 OFF
S8 OFF S9 ON audio processor on
S8 ON S9 OFF audio processor off
S10 ON treble boost on
S10 OFF treble boost off
fast response
suited to music sources
slow response
suited to voice sources
Channel Settings
Freq kHz S1 S2 S3 S4 S5 S6
1290 ON ON ON ON ON ON
1300 OFF ON ON ON ON ON
1310 ON OFF ON ON ON ON
1320 OFF OFF ON ON ON ON
1330 ON ON OFF ON ON ON
1340 OFF ON OFF ON ON ON
1350 ON OFF OFF ON ON ON
1360 OFF OFF OFF ON ON ON
1370 ON ON ON OFF ON ON
1380 OFF ON ON OFF ON ON
1390 ON OFF ON OFF ON ON
1400 OFF OFF ON OFF ON ON
1410 ON ON OFF OFF ON ON
1420 OFF ON OFF OFF ON ON
1430 ON OFF OFF OFF ON ON
1440 OFF OFF OFF OFF ON ON
Page 7 of 9
PROCASTER AMTX100 AM Transmitter
Installation and Operation
1450 ON ON ON ON OFF ON
1460 OFF ON ON ON OFF ON
1470 ON OFF ON ON OFF ON
1480 OFF OFF ON ON OFF ON
1490 ON ON OFF ON OFF ON
1500 OFF ON OFF ON OFF ON
1510 ON OFF OFF ON OFF ON
1520 OFF OFF OFF ON OFF ON
1530 ON ON ON OFF OFF ON
1540 OFF ON ON OFF OFF ON
1550 ON OFF ON OFF OFF ON
1560 OFF OFF ON OFF OFF ON
1570 ON ON OFF OFF OFF ON
1580 OFF ON OFF OFF OFF ON
1590 ON OFF OFF OFF OFF ON
1600 OFF OFF OFF OFF OFF ON
1610 ON ON ON ON ON OFF
1620 OFF ON ON ON ON OFF
1630 ON OFF ON ON ON OFF
1640 OFF OFF ON ON ON OFF
1650 ON ON OFF ON ON OFF
1660 OFF ON OFF ON ON OFF
1670 ON OFF OFF ON ON OFF
1680 OFF OFF OFF ON ON OFF
1690 ON ON ON OFF ON OFF
1700 OFF ON ON OFF ON OFF
Page 8 of 9
PROCASTER AMTX100 AM Transmitter
Installation and Operation
Compliance Statement
AM Transmitter
Model: AMTX100
Manufacturer: ChezRadio
FCC ID: VCJ-AMTX100
IC: 7378A-AMTX100
This device complies with Part 15 of the FCC Rules. Operation is subject to the following two
conditions: (1) this device may not cause harmful interference, and (2) this device must accept
any interference received, including interference that may cause undesired operation.
Warning:
Changes or modifications not expressly approved by ChezRadio could void the user’s authority to
operate the equipment.
Page 9 of 9
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