ALPHA 9500 HF LINEAR AMPLIFIER Interim OPERATING MANUAL © 2007 Alpha Radio Products, Inc All rights reserved Specifications subject to change without notice ALPHA 9500 Interim OPERATING MANUAL www.alpharadioproducts.
ALPHA 9500 Interim OPERATING MANUAL www.alpharadioproducts.
Table of Contents ALPHA 9500 Interim OPERATING MANUAL www.alpharadioproducts.
ALPHA 9500 Interim OPERATING MANUAL www.alpharadioproducts.
ALPHA 9500 Interim OPERATING MANUAL www.alpharadioproducts.
ALPHA 9500 Interim OPERATING MANUAL www.alpharadioproducts.
1 Introduction 1.1 General Description Congratulations on your purchase of a professional quality Alpha 9500 amplifier! With proper installation and care, you can expect to enjoy your Amateur Radio hobby with this amplifier improving your signal for many years to come. Please study this manual carefully before operating your amplifier for the first time.
1.2 Amplifier Capabilities CAUTION: It is extremely important to thoroughly review the Installation and Operation sections of this manual before attempting to use the Alpha 9500. Failure to do so could result in serious damage not covered under warranty. • Continuous RF Output. The 9500 is capable of 1.5 kW continuous RF output on all commonly used modes and on any authorized amateur frequency from 1.8 to 29.7 MHz. • Compatibility with popular amateur transceivers and exciters.
proper lifting techniques and two people when moving the amplifier. • The Alpha 9500 is designed to meet international safety standards and FCC regulations. However, one should always remember that the equipment works with high voltages that can be LETHAL! This operating manual holds information, cautions and warnings that must be followed to ensure safe installation and operation. Read Chapter 1 before attempting to unpack or operate the Alpha 9500 amplifier.
• Tech Tips • Legacy Equipment Information • FAQs • You can e-mail us for customer support at service@alpharadioproducts.com or you can send your request by fax to 303.473.9660. • Our phone number is 303.473.9232 ALPHA 9500 Interim OPERATING MANUAL www.alpharadioproducts.
2 Quick Start Information 2.1 Overview This section explains in brief the items you need to consider when setting up your Alpha 9500 amplifier. If you already have a well-designed shack and have used an amplifier before, please review the items below to make sure you have considered all the critical items for proper installation and operation.
2.4 Unpacking __ __ __ __ __ __ Unit Checked for Damage? Blower screw removed? Transformer Installed? (Section 4.2.1, 4.2.2) Power Cord Connector Attached? (Section 4.2.3) Amplifier Grounded Properly? (Section 4.4.1) Amplifier Cover Replaced and Secured? (Section 4.4.2) 2.5 Operation __ All Exciter Interconnections Set? (Section 6.2) __ Exciter Drive Correctly Set? (Section 6.1.1) __ Amplifier Tuned to Antenna System? (Section 6.3.6) ALPHA 9500 Interim OPERATING MANUAL www.alpharadioproducts.
3 Station Engineering Considerations 3.1 Overview The Alpha 9500 is capable of dramatically improving the performance of your amateur station. It is important that you observe good engineering practices to achieve all the benefits of such a station in a safe and reliable manner.
Figure 3.3 - Minimum clearance for proper airflow 3” 3” To ensure adequate cooling make sure the top and rear of your amplifier have at least 3” of clearance to allow unobstructed airflow. result in outlet air being drawn back into the amplifier air intake and recirculated, thus getting hotter and hotter and resulting in degraded amplifier performance or even failure. If you are designing your own console, consider putting in additional fans and/or ducting to deal with waste heat.
replace them. Doubling-up on insulators is also easy to do, and may prevent problems. If there is any chance of people, animals or objects coming close to the antenna, take steps to move it higher, or place barriers so that this cannot happen. Check the SWR of your antenna; if you have a favorite part of any band you use most often, consider adjusting the antenna for minimum SWR in this part of the band. 3.5 Coax and Connectors The importance of a well-constructed feed-line system cannot be overstated.
ALPHA 9500 Interim OPERATING MANUAL www.alpharadioproducts.
4 Unpacking & Preparation 4.1 Unpacking Remove the strap securing the two boxes to the pallet. Inspect both boxes for physical damage. Save all packing material and pallet for possible future use. Contact 303-473-9232 if shipping damage is found. Carefully unpack the amplifier and transformer. Carefully remove the amplifier and place it on a workbench or table where you can install the power transformer. 4.
4.2.1 Remove the Blower Screw Place the amplifier on the bench or desk where it is to be used and remove the cover screws and the cover. With the cover removed, rotate the amplifier on to its right hand side as shown in figure 4.1. While looking at the bottom you will see a screw labled “BLOWER SCREW”, this screw holds the blower securely in place during shipping. Before operation remove this screw. Before operation remove this screw.
CAUTION: PROCEED SLOWLY to avoid bumping and damaging adjacent wires, connectors or components. While the top cover is removed, make sure the tube is firmly seated in its socket, rubber exhaust chimney is fully and correctly installed, and anode connector is tightly clamped to the tube. The silicone rubber chimney installed on the 8877 tube is a critical part of the cooling system.
1 Figure 4.2 Transformer Installation 1. On a flat surface, with plenty of room, carefully rotate the amplifier on to its right side (power supply/transformer side). Rotate the transformer onto its right side, placing the transformer squarely on the transformer shim. 2 2. Slowly move the amplifier and transformer together making sure to align the nuts on the transformer with screw holes in the bottom of the amplifier. 3.
4.2.3 Transformer Connections 4.2.3.1 AC to transformer connection 1 Found towards the back of the amp & transformer. Connect the Molex plug on the transformer to the connectior at the back of the amp as shown in the photograph. 2 First make sure the connectors are properly aligned 3 Gently but firmly press the connectors together till they are fully mated. The connection should look like this when you are done. ALPHA 9500 Interim OPERATING MANUAL www.alpharadioproducts.
4.2.3.2 High Voltage Connection 1 Locate the 7pin connector coming from the transformer. Connect the transformer to the 7-pin connector on the high voltage board (the lower of the two pictured boards). 2 This is the mains connector, move it out of the way while working with the HV connection 3 Align the HV connector, making sure that all pins are in their appropriate slots.
4.2.3.3 Mains Connection 1 Connect the transformer to the 2-pin connector on the mains board (the upper of the two pictured boards). Locate the 2pin connector coming from the transformer. 2 Align the Mains connector, making sure that both pins are in their appropriate slots. 3 Gently but firmly push the connector together, ensuring that it is properly mated. ALPHA 9500 Interim OPERATING MANUAL www.alpharadioproducts.
4.2.4 Power Cord Connections WARNING! To avoid the hazard of a potentially fatal electric shock and/or severe damage to the ALPHA 9500 and other equipment, always use an AC plug that is appropriate for the primary mains voltage, current rating and configuration. NEVER use 120V-type plugs to connect to power receptacles for 190-250V circuits.
4.3 AC Primary Connections When the Alpha 9500 is powered on, the line voltage is measured and the appropriate tap setting is chosen and set. The amplifier does not reset the tap as long as it is powered up. External Fan Figure 4.3 Interlock Blower Transformer AC Connector Tube RF Choke Crowbar Tank coil Band switch Power Supply Mains Board Below are some considerations at the high end and the low end of this voltage range that are rarely encountered. Low Voltage vs.
voltages (less than 100 volts). If you do, be aware that the higher current at the lower voltage will significantly warm the power cord for the amplifier. The cord (as well as fuse holders and some internal connectors) are operating near their maximum ratings due to the current demand at lower voltages. Be sure that the AC cord is not coiled too tightly or placed where normal air flow is restricted because the cord could overheat.
Replace all attachment screws. Use only the 6-32 screws supplied with the amplifier and do not tighten any of the screws until all are started. Do not attempt to operate the amplifier with the cover removed or only placed back on the unit without the attachment screws. This WILL cause damage to the Alpha 9500 and may also lead to injury or death to the operator. 4.
The Alpha 9500 does not generate or use ALC voltages to control an exciter. Key In line from radio Key Out line (optional) to radio RS232 port RF outputs 1 -4 to antenna 1500 watts USB port ALPHA 9500 Interim OPERATING MANUAL www.alpharadioproducts.
5 Theory of Operation 5.1 Theory of Operation - Overview The Alpha 9500 uses a single 3CX1500 (8877) high-mu external anode triode ceramic tube for amplification. The main power supply is an unregulated transformer/rectifier/capacitor power supply for the high voltage (HV) and heater circuits. All other power supplies are regulated. The biasing and tank circuits are similar in most respects to its predecessor, the Alpha 77.
The amplifier is designed to use a single 8877 triode tube manufactured by CPI Eimac Company of San Carlos, CA. The amplifier design uses this tube well within the published ratings. The tube is operated in Class AB1, with a plate voltage of 3,300V (nominal, full output, key down), and a cathode voltage of 9.4 V. 5.3 Output Tank Circuit The output tank circuit of the Alpha 9500 is designed to provide reliable high efficiency, low distortion performance in a very compact volume.
port. Also on the mains board is a step-start circuit. This circuit consists of a relay and a resistor, which are time-sequenced to limit the inrush current into the amplifier when it is first turned on. 5.5.2 High Voltage Board The main high voltage for the amplifier is created on this board using a full-wave bridge rectifier and a bank of capacitors. This power supply has two 10-ohm resistors, one in the positive (B+) lead, and the other in the negative return, which goes to the tube cathode.
This board is housed in the tube deck and consists of a set of Pi-L filters controlled by a set of 5 relays which are enabled, based on the band switch setting to choose which filter to use. 5.9 Center Partition Board This contains the RF decoupling circuit on the B+ line as well as the “crowbar” safety circuit. This safety device consists of a piece of spring metal, which shorts out the B+ line when the top cover of the amplifier is removed. ALPHA 9500 Interim OPERATING MANUAL www.
6 Operation & Maintenance The ALPHA 9500 is extremely easy to operate, but failure to carry out each procedure exactly as described in this manual is likely to lead to amplifier damage, which is not covered under warranty. Damage to other station equipment may also result. 6.1 Before Operating Your Alpha 9500 6.1.1 Setting Input Drive You must set the transceiver output power properly. Virtually all damage to date has resulted directly from severe overdrive.
One of four situations will typically result in a fault: • Incorrect gain. Output too low or too high for the input power supplied. • High reflected power (SWR). • Incorrect plate voltage (too high). • RF arc in output circuit including antenna. If the 9500 encounters unsafe operating conditions, it enters a protective “Fault” mode. When this happens, the tube is biased off and the relays are placed in the bypass mode, so that RF from the radio goes directly to the antenna.
If you are certain that you have taken care of the problem that caused the fault, you may turn the amplifier back to operate and proceed with use. 6.1.5 Lightning Protection Induced energy from nearby electrical storms or other power transients may damage components. Such damage is not covered under warranty. It is important to use a good lightning arrestor, however the only lightning proof solution available is to disconnect antenna feedlines and AC power when the equipment is not in use. 6.1.
Yeasu Kenwood Older Transceivers RF – T/R – Connection with the RCA “TX GND” connector. Also with the DIN “Band Data” connector. See the transceiver User’s Manual for information. RF – T/R – See the transceiver User’s Manual for information on connecting to external amplifiers. See the transceiver User’s Manual for information on connecting to external amplifiers. 6.
The following procedure may be used for to save settings for each segment and band setting in the User 1 and User 2 memories. Engage the auto-tune functionality by pushing the Auto button. choose the correct antenna on the amplifier, set a steady carrier and apply drive. Increase the drive (with Auto engaged), until the amplifier achieves 1500 watts output. At this point choose User 1 and the appropriate segment button and then push the Save button.
RF POWER kW These LEDs display the forward power SWR GRID CURRENT PLATE CURRENT PLATE VOLTAGE GAIN Fwd These LEDs display the SWR seen by the amplifier This bar graph shows the grid current in mA This bargraph shows the plate current in amps Ip Vp Ig SWR FLT DIM SND PEP DEL OPER STBY ON(AMP) ON/OFF(ANT SEL) This bargraph shows the plate voltage in kV This set of LEDs shows the gain of the amp in dB The numbers displayed in the seven segment display are controlled by the settings of the switches belo
operator can switch between the dummy load and the antenna at the flip of a switch. 6.3.3 Grid Current Information The ALPHA 9500 operates in Class AB2 when delivering maximum output power consistent with excellent linearity. A small amount of grid current flows which can be monitored via the grid current bar graph. As overdrive approaches, grid current increases rapidly and the red grid LEDs will be illuminated. At maximum output and efficiency, the red grid LED lights should not be illuminated.
6.4 Normal Use 6.4.1 Tubes The Alpha 9500 makes use of a single 8877 (3CX1500A7) ceramic triode tube manufactured by CPI Eimac corporation. 6.4.2 Interlocks The ALPHA 9500 is equipped with a cover interlock switch intended to remove primary power from the amplifier, and a crowbar to short-circuit the high voltage to chassis whenever the cover is lifted.
CAUTION: DAMAGE RESULTING FROM USE OF A FUSE OF INCORRECT SIZE OR TYPE WILL NOT BE COVERED UNDER WARRANTY AND MAY VOID THE WARRANTY. 6.5 Standard Maintenance Tasks The amplifier interior, particularly high voltage areas, should be cleaned with a vacuum cleaner and a soft bristle brush frequently enough to prevent visible accumulation of dust.
ALPHA 9500 Interim OPERATING MANUAL www.alpharadioproducts.
8 Glossary The following terms are used in this manual. Detailed explanations may be found in various publications including the ARRL Handbook. AB1- Modulation class AB1. Provides good linearity in push-pull configuration.
dot or dash, allowing the operator to hear any signal being sent. RCA- Radio Corporation of America. Also a type of interconnecting plug. RF- Radio frequency RG-x/x- Coaxial cable type RMS- Root mean square RTTY- Radioteletype SSB- Single-sideband SSTV- Slow-scan television STBY- Standby SWR- Standing wave ratio. A measure of antenna and feedline efficiency.
