Alpha 8100 Operating Manual

ALPHA 8100

HF LINEAR AMPLIFIER

OPERATING MANUAL

Speciﬁcations subject to change without notice

ALPHA 8100 OPERATING MANUAL

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ALPHA 8100 OPERATING MANUAL

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Table of Contents

1 Introduction 7

1.1 General Description 7

1.2 Amplifier Capabilities 8

1.3 Shipping Information 8

1.4 Safety Information – Installation and Operation 8

1.5 Owner Assistance 9

2 Quick Start Information 11

2.1 Overview 11

2.2 Station Engineering Considerations - Checklist 11

2.3 Preparation 11

2.4 Unpacking 12

2.5 Operation 12

3 Station Engineering Considerations 13

3.1 Overview 13

3.2 AC Power Source 13

3.3 Air Flow 13

3.4 Antennas 14

3.5 Coax and Connectors 15

3.6 RF Safety 15

4 Unpacking & Preparation 17

4.1 Unpacking 17

4.2 Installing the Power Transformer 17

4.2.1 Install the Power Transformer 18

4.2.2 Connecting the Transformer Power Plugs 20

4.2.3 Power Cord Connections 21

4.2.4 Important Information About Operation from 90-130V AC 21

4.3 AC Primary Connections 22

4.4 Complete the Transformer Installation 25

4.4.1 RF Grounding 25

4.4.2 Replacing the Amplifier Cover 25

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4.4.3 Blower Preparation 25

4.5 Amplifier/Station Interconnections 25

4.5.1 Coaxial Cable Types & Connectors 25

4.5.2 T/R Control Cable 26

4.5.3 ALC 26

5 Theory of Operation 29

5.1 Theory of Operation - Overview 29

5.2 Tubes 29

5.3 Output Tank Circuit 30

5.4 Tube Deck 30

5.5 Mains Board 30

5.6 High Voltage Board 31

5.7 Control Board 31

5.8 Display Board 31

5.9 Output Wattmeter Board 31

5.10 Center Partition Board 32

6 Operation & Maintenance 33

6.1 Before Operating Your Alpha 8100 33

6.1.1 Setting Input Drive 33

6.1.2 Dealing with Faults 33

6.1.3 High SWR Considerations 35

6.1.4 Operating at Less Than 1.5 kW Requires Retuning 35

6.1.5 Lightning Protection 36

6.1.6 Operating in Bypass Mode 36

6.1.7 Never Use Transceiver Automatic Antenna Tuner 36

6.2 Transceiver Connections 36

6.3 Initial Setup & Tuning 37

6.3.1 Control Functions 37

6.3.2 Tune-Up 38

6.3.3 Grid Current Information 38

6.3.4 ALC 39

6.3.5 Turning On The Amplifier 39

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6.3.6 Tuning the Amplifier 40

6.4 Normal Use 43

6.4.1 Tubes 43

6.4.2 Interlocks 43

6.4.3 Fuses 43

6.4.4 Plate Overcurrent Relay 44

6.4.5 Idling Plate Current and Electronic Bias Control (Ebs) 44

6.4.6 RF and Mistuning Protection 44

6.5 Standard Maintenance Tasks 45

7 Troubleshooting Hints 47

7.1 Normal Troubleshooting 47

7.2 Troubleshooting Using the Serial Port 50

8 Glossary 55

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1 Introduction

1.1 General Description

Congratulations on your purchase of a professional quality Alpha 8100 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.

The Alpha 8100 is a self-contained manual tune HF linear power ampliﬁer capable of continuous operation at 1500 W peak power output on SSB, keyed CW, SSTV, RTTY, digital modes or FM, with no time limit.

Other Alpha products available to enhance your use and enjoyment of the 8100 ampliﬁer include:

• Alpha 2100 full 1500-watt rated 50-ohm dummy loads and

• Alpha 4500 series SWR meters / Wattmeter

See our web site at www.alpharadioproducts.com or call 303-473-9232 for further information.

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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 8100. Failure to do so could result in serious damage not covered under warranty.

• Continuous RF Output. The 8100 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. The 8100 requires approximately 50-65 W peak RF drive for 1.5 kW output.

• Capable of full CW break-in, QSK and all digital modes when used with any appropriate transceiver.

• Protective functions are built in. The control system incorporates protective functions that minimize the probability of accidental damage to the ampliﬁer or its power tubes. In most cases, when one of the protective functions is “tripped,” the ampliﬁer will go to Standby.

1.3 Shipping Information

The Alpha 8100 ampliﬁer ships in two heavy-duty cardboard cartons. One carton holds the power transformer and weighs 43 lb (20 kg) and the second carton contains the ampliﬁer and weighs 38 lb. (17 kg). Both of these cartons are mounted on a wooden pallet and strapped down for a total weight of 98 lb. (45 kg).

Alpha recommends that you retain the pallet and the cartons after installation in the unlikely situation that you need to ship the unit later. Contact Alpha at 303.473.9232 for shipping advice and assistance.

1.4 Safety Information – Installation and Operation

• Make sure the Alpha 8100 is located where there is good air circulation all around and on top of the cabinet. The unit may become hot during operation.

• The Alpha 8100 weighs approximately 68 pounds when the transformer is installed. Use proper lifting techniques and two people when moving the ampliﬁer.

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• The Alpha 8100 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 8100 ampliﬁer.

Warnings: What Not to Do

• Never open the ampliﬁer case without unplugging the unit from the wall outlet.

• Never stick objects into holes in the case.

• Never touch an antenna during transmission.

• Never attempt to turn on the ampliﬁer without the cover securely in place (all attachment screws reinserted).

• Never turn the ampliﬁer back on after a hard fault without waiting at least 20 seconds.

• Always resist the temptation to immediately hit the ON button after the ampliﬁer faults to power off.

• Never allow liquids to enter the ampliﬁer through the cover holes.

Warnings posted in this manual should be read and thoroughly understood by users. Failure to perform procedures properly may result in ampliﬁer damage, ﬁre hazard, or electric shock.

1.5 Owner Assistance

Technical Assistance from Alpha Radio Products is available from several sources.

• The Alpha Radio Products web site is www.alpharadioproducts.com. Click on Support and follow the instructions. Many typical problems and their solutions are listed on this site. On this site you can get the following assistance:

• Technical Support

• Repair Information

• Software Downloads

• Manuals

• Tech Tips

• Legacy Equipment Information

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• 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.

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2 Quick Start Information

2.1 Overview

This section explains in brief the items you need to consider when setting up your Alpha 8100 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.

If you are using an ampliﬁer for the ﬁrst time, please skip this section and go to sections 3, 4, and 5 for a more detailed explanation of how to set up your shack for maximum safety and operating enjoyment.

If you have installation questions, do not hesitate to contact Customer Support. We much prefer to address questions prior to power up.

2.2 Station Engineering Considerations - Checklist

Make sure you have properly addressed the following concerns (Section 2.3 below) before installation of your Alpha 8100 ampliﬁer. If you are unsure of any of these items, please read the noted sections carefully.

2.3 Preparation

__ 220V AC Power in shack? (Section 3.2) __ Ampliﬁer placed with proper airﬂow? (Section 3.3) __ Antenna ready for 1,500W? (Section 3.4) __ Adequate RF cabling? (Section 3.5)

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2.4 Unpacking

__ Unit Checked for Damage? __ Transformer Installed? (Section 4.2.1, 4.2.2) __ Power Cord Connector Attached? (Section 4.2.3) __ AC Primary Voltage Set? (Section 4.3) __ 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)

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3 Station Engineering Considerations

3.1 Overview

The Alpha 8100 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. This section provides a few hints for important operational considerations, but it is recommended that the user also consult a good source of general information such as “The Radio Amateur’s Handbook” by the ARRL, especially if this is the ﬁrst high-power ampliﬁer you have used.

3.2 AC Power Source

This ampliﬁer runs best when powered by a 200V - 240V AC circuit. If you do not have a 220V AC outlet in your shack, you will need to get a licensed electrical contractor to install one. A minimum of a 20 amp capacity is required. A 20 amp breaker on your 220V circuit is sufﬁcient. There are many styles of plugs, some of which are country-speciﬁc. For this reason, the ampliﬁer is not shipped with a power plug. Select a location for the outlet as close as possible to where you expect to operate the 8100. If you are not sure, or contemplate moving the ampliﬁer, you may choose to get a second outlet installed at the same time. Ask your contractor for two or three matching plugs during installation as there are several styles of connector available. Ask the contractor to measure the voltage and record it, so you can set the line voltage tap on the 8100 appropriately. If possible, have the contractor measure the line voltage with a 10 amp current draw, and use this value for setting the transformer tap. The Alpha 8100 can run when connected to a 110V AC outlet. However, you WILL NOT achieve full legal limit output in this case. If the ampliﬁer is connected to a 110V AC outlet, you should not expect more than 1000 W output.

3.3 Air Flow

It is critical that airﬂow around the Alpha 8100 remain unimpeded at all times. Keep the top of the ampliﬁer clear of any restrictions. If you are mounting the ampliﬁer in a console, make sure that the exhaust air is properly and fully removed from the console. Poorly designed consoles can result in outlet air being drawn back into the ampliﬁer air intake and recirculated, thus getting

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Figure 3.3 - Minimum clearance for proper airﬂow

3”

To ensure adequate cooling make sure the top and rear of your ampliﬁer have at least 3” of clearance to allow unobstructed airﬂow.

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. Try to minimize the possibility of dust or other contamination getting drawn into or falling on the ampliﬁer. It is also advisable to periodically (at least annually) clean the dust out of your ampliﬁer for continued ﬂawless operation. Alpha Radio Products recommends the use of compressed air for dust removal.

3.4 Antennas

Many antennas that are suitable for general use are unsuited for operation with a full 1500 W of power. At this power level in a 50-ohm circuit, the RMS current is 5.5 amps and the peak RF voltage is 387 volts. With a 2:1 SWR, these values double to 11 amps and 775 volts. The actual voltage and current at various points in or on your antenna may actually be many times these values. On a simple dipole with sharp wire ends, corona (localized ionization) can easily occur. Corona can (and has!) led to ﬁre in nearby objects. Traps in beams and verticals can heat up signiﬁcantly during high power operation. Instances of melting or ﬂashover of traps have occurred in many installations where insufﬁcient thought has been given to their ratings. If an antenna has been deployed for a long period of time, it may be worth taking it down for inspection prior to full power operation. If any insulators are cracked or show signs of “tracking”, replace them. Doubling-up on insulators is also easy to do, and may prevent problems. If there

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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. After all, the purpose of the ampliﬁer is to provide approximately 2 S units (12+ dB) of improvement in your radiated signal. All too often, installation problems are encountered where cheap, poor or under-rated coax and connectors are used. These often are responsible for at least one S unit of degradation. (This means you could have bought a 375 W ampliﬁer and achieved the same radiated signal by buying good quality feed-line components!) Use the lowest loss 50-ohm coaxial cable you can obtain. Use new, clean connectors installed according to the manufacturer’s recommendation. Clean the connectors after soldering them, and before mating them with the ampliﬁer. Make sure any excess solder is removed from the connector; likewise remove any fragments of braid etc. Never use old coax, which may have had moisture penetrate under the jacket. Run the coax in straight lines as much as possible. Support it frequently using noncompressive clips so that it does not hang or stretch under its own weight. Avoid sharp bends (most manufacturers will specify a minimum bend radius for their product). Make sure the connection from feed-line to antenna is waterproof. Provide for disconnection of the feed-line when it is not in use; this protects against damage caused by power surges and lightning strikes, which are not covered under the ampliﬁer warranty.

3.6 RF Safety

The FCC requires users to check their installations for compliance with published values for allowable exposure to RF ﬁelds. This information is available in ARRL publications, FCC printed rules, and on the web. Alpha Radio Products strongly recommends that this be done for any installation, both ﬁxed and at an expedition or contest site.

If you have any questions regarding engineering your 8100 into your amateur radio station, please visit our online technical support website at: www.alpharadioproducts.com

ALPHA 8100 OPERATING MANUAL

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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. This is a good time to remove the screws on the back panel which lock down the blower motor for transportation. Retain these screws, as they should be re-installed if the ampliﬁer is shipped again.

4.2 Installing the Power Transformer

It is recommended that the power transformer be installed when the amp is at or near the place it is to be used. The chassis of the 8100 is designed for the mechanical loads it experiences when the ampliﬁer is on a ﬂat surface with the tilt-bail up or down. If the ampliﬁer is tilted too far, such that the transformer is cantilevered or “hanging out” to any degree, the chassis of the ampliﬁer can distort. This may affect a number of things, from the alignment of screw holes on the top cover to the band-switch alignment and tension. If the ampliﬁer is moved, even if only from one site to another locally, remove the transformer to avoid the possibility of damage.

CAUTION:

Do not operate ampliﬁer without the cover in place and all cover screws installed. Do not operate the ampliﬁer without a good RF ground connection on the rear panel ground terminal.

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+ 39 hidden pages

Alpha 8100 Operating Manual

Specifications and Main Features

Frequently Asked Questions

User Manual