Mirage B 1018 G
This compact, rugged, VHF RF power amplifier greatly improves signal-quality and range. This unit contains a low-noise GAsFET receiving amplifier, a 160-watt power amplifier, and associated control and protection circuitry.
This amplifier operates from any well-filtered direct-current 11-15 volt power source capable of supplying 30 amperes under full-load. The power source must be either negative grounded or totally ground independent.
Warning, never use this unit with: 1.) positive-ground supplies
2.) vehicles having positive-ground batteries
3.) power sources exceeding 16 volts
Always fuse power leads at the battery with 30-ampere fast-blow fuses.
This amplifier has the following important features:
1.) Automatic RF actuated transmit and receive switching or manual switching 2.) Active bias for greatly improved SSB linearity
3.) Low-noise GAsFET receive preamplifier
4.) True push-pull circuitry and clean RF layout for excellent stability 5.) Excess SWR and overdrive protection
6.) Remote control capabilities
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Table of contents
0.0Quick Connect
Important: Read this section first!
1.0Mounting Considerations
1.1Cooling and Temperature
1.2Power Wiring
1.3RF and Controls Cables
1.4Mobile Mounting Conderations
1.5Home or Fixed Installations
1.6Repeater Mounting
2.0Radio or Exciter
2.1Drive Level
2.2Duty Cycle
2.3T/R Control or “Keying”
2.4Wiring
3.0FM, CW and Non-Linear Modes
3.1Drive Power
3.2Duty Cycle CW and FM
3.3Feedlines and Antennas
4.0SSB and Linear modes
4.1Splatter and Distortion
4.2Drive Power
4.3Duty Cycle
4.4T/R Control or Switching
4.5Power Output
4.6Antennas and Feedlines
5.0Receiving Preamplifier (Pre-Amp)
5.1Signal-to-noise Ration
5.2Intermodulation (IMD) Products
6.0In Case of Difficulties
6.1Does Not Transmit or Receive at All
6.2Nothing Lights or Seems to Work
6.3Transmit OK, Does Not Amplify Receive
6.4Receives OK, Does Not Amplify Transmit
6.5Continuously Trips Fault Light
6.6Relay Chatters or Clicks Off and On
6.7Technical Assistance
6.8Ordering Parts
7.0Notes
8.0Schematic
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0.0 QUICK CONNECT
1.) Mount or place the amplifier in a cool area. The best mounting position will place the long length of heatsink fins vertical.
The amplifier must have sufficient cool air supply. Do not mount in confined or hot locations, or where exposed to moisture.
2.) Connect the power leads to the battery or power supply.
Be sure to fuse the red positive-lead at the battery or power supply with a 30-ampere fuse. The red lead must always be positive, with an operating voltage of 12-15 Vdc. We do NOT recommend connecting the black lead directly to a vehicle battery terminal. Connect the black lead to the vehicle’s chassis with a good solid connection.
3.) Connect the radio to the UHF-style female RADIO connector with any length or type of good-quality 50-ohm coaxial cable.
Any size or length 50-ohm coaxial cable will work on the INPUT, just be sure the jumper is good.
4.) Connect the antenna (or power meter) to the ANTENNA connector through any length of good-quality 50-ohm coaxial cable capable of handling 200 watts of power.
Any size or length 50-ohm cable will work, as long as losses are acceptable. The cable must safely handle 200 watts at 150 MHz. Be sure connectors are installed and soldered properly!
5.) The switches in this unit are self-explanatory. They are MODE, PRE-AMP, and POWER.
a.) The MODE switch adds time to the transmit-relay in the SSB/CW position. This allows SSB or CW operation without excessive relay chatter or word chopping. It is normally not necessary to use the SSB/CW mode position when using the RELAY port for relay control.
b.) The PRE-AMP switch adds a low-noise receiver pre-amplifier, which improves signals if receiver gain is marginal. In congested areas, it may be advisable to NOT use the preamp to reduce receiver overloading.
c.) The POWER switch controls the transmitting amplifier, and resets any overloads.
6.) The FAULT light illuminates whenever excessive drive power from the radio is applied, or reflected power from the antenna exceeds a preset value. This light indicates the protection circuits have locked-on, preventing the amplifier from keying.
If the FAULT indicator is on, you must check drive power and antenna reflected power. Drive power must be below 10 watts and Reflected power must be below 20 watts (at full output). If SWR is over 2:1, it is unacceptable to run this unit at full power.
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1.0 MOUNTING CONSIDERATIONS
To insure long life and optimum performance, pay careful attention to mounting and wiring. This unit has rubber feet for use where movement is not a problem.
Warning, never install this unit in areas where: 1.) ambient temperatures exceed 110°F (43°C)
2.) exposed to moisture, excessive dust, or dirt
3.) subjected to mechanical shock or vibration
1.1 COOLING AND TEMPERATURE
Reduced operating temperatures almost always extend the life of electronic components.
If the heatsink becomes uncomfortable to touch, the amplifier may require additional cooling.
Heatsink temperatures above 140°F indicate the need for additional cooling, such as re-mounting the amplifier in a cooler location or the addition of a small fan blowing on the heatsink. Mirage has a cooling kit, P/N FK-18. This kit includes a 12 Vdc fan and mounting bracket.
Note: As temperature in the mounting area increases, especially if air is not moving, cooling becomes less effective and the amplifier will “run hotter”. If cooling is a problem, the largest change will come from forcing air over the heatsink with a small fan.
The heatsink in this amplifier is sized for ICAS operation at 160 watts carrier output with a 33% long-term duty cycle. Do not exceed 5 minutes total accumulated transmitting time without ten minutes of total accumulated resting time. This is a rough guideline; actual duty-cycle limitations depend on many factors.
On SSB and AM, because power is greatly reduced, the duty cycle is much longer. The general guideline is to watch the heatsink temperature, and improve cooling or reduce duty cycle if the heatsink is uncomfortable to touch.
If possible, especially if cooling might be marginal and there is no external air blowing across the heatsink, mount the amplifier with heatsink fins vertical. This allows natural convection to circulate air.
1.2 POWER WIRING
This amplifier has two main power leads. The red lead connects to the floating (not grounded) positive 12-15 Vdc battery or power supply terminal. The black lead is the negative lead. It is grounded inside the amplifier, and is common with the metal case and all connector grounds.
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To reduce fire hazards or the chance of equipment damage, the red lead must always be fused with a 30-ampere fuse at the battery. Some power supplies have internal current protection. Power supplies without current limiting must be protected by properly sized fuses located at the supply.
The black lead should connect to the negative terminal through the vehicle chassis. We do not recommend connecting the black lead directly to a battery post.
The heavy RED conductor and black battery return and/or chassis ground conductors carry full operating-current. This current can reach 30 amperes. For maximum power output, it is important to minimize the voltage drop along these conductors. For maximum output power, all high current leads (including the ground lead) should be kept as short as reasonably possible. Be sure connections are good. Never extract this power from under-dash wiring, unless the vehicle manufacturer tells you it is safe.
A fuse is must always be installed at the battery to prevent wiring fires. If a fuse is not added, you run the risk of a fire if the wiring is accidentally shorted between the battery and amplifier. NEVER omit this fuse, no matter how safe you think it is!
Suitable fuses and holders are generally available from electronics, car stereo, and automotive parts stores. This device requires a 30-ampere fuse.
The following chart gives the approximate peak voltage drop in volts per foot of a single supply wire with 30 amperes of current. This chart assumes the negative return to the battery (through the vehicle chassis) has the same resistance as the positive lead, or that a home power supply uses equal length and size conductors for positive and negative (ground) leads.
AWG |
Voltage Drop |
Maximum Length For Full |
(single conductor) |
at 30 amps |
Performance |
|
||
|
|
|
10 gauge |
0.03 V/ft |
8 ft. |
|
|
|
8 gauge |
0.02 V/ft |
12 ft. |
6 gauge |
0.011 V/ft |
23 ft. |
|
|
|
4 gauge |
0.007 V/ft |
36 ft. |
|
|
|
For best performance, voltage drop in high-current positive and ground leads should be limited to 0.5 volts or less at maximum current of 30 amperes.
1.3 RF AND CONTROL CABLES
Length of RF and control cables is not critical.
The RADIO connector of this amplifier is a SO-239 (UHF Female). UHF-style connectors are perfectly fine at frequencies below UHF, and have almost immeasurable loss at VHF and lower. The amplifier input is matched for 50-ohms, and the amplifier is very stable. The input cable can be any reasonable length, as far as the amplifier is concerned.
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