Alpha Radio Products 8410 User manual

ALPHA 8410
HF LINEAR AMPLIFIER
OPERATING MANUAL
© 2009 Alpha Radio Products, Inc
6185 Arapahoe Ave.
Boulder, olorado 80303
Phone [phone]
All rights reserved
Specifications subject to change without notice - Rev. 102
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Serial Number ______________________
Date Shipped _______________________
Software Version ____________________
Order Number ______________________
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Index
Specifications 4
Introduction 5
Quick Start Information 9
Station Engineering Considerations 11
Unpacking and Preparation 15
Theor of Operation 23
Operation and Maintenance 27
Trouble Shooting Hints 39
Glossar 43
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Specifications
Frequency 1.8-29.7 KHz
Input drive Level 50 Watts Nominal
Power Output 1500 watts
SWR Tolerance 3:1
Duty Cycle 100 %
Tubes 2x VTX-X118 Alpha, (4CX1000A)
Inter Modulation Level 30 dB minimum, Two Exciter
Harmonics -50 dBc
Mode of Operation CW, SSB, FM
Input AC Voltage 100-240 Selectable
AC Current <13 5mps @240 VAC @1500 watts
Input Impedance 50 Ohms
Output Impedance 50 Ohms
RF Connectors SO-239
Cooling Forced Air
Size 17.3 W x 7H x 21.0D Including Fan
Space
Weight 70 lbs., 31.8 kg
T/R Relay Vacuum QSK
Tuning /Band switching Manual
Display Bargraph LED
Interface USB
Protection Against all common faults
RF Bypass Level Less than 500 watts
This amplifier meets or exceeds all technical specifications listed above.
Technician ____________________________ Date ____________________
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1 Introduction
1.1 General Description
ongratulations on your purchase of a professional quality Alpha 8410 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 8410 is a self-contained manual tune HF linear power amplifier capable of
continuous operation at 1500 W peak power output on SSB, keyed W, SSTV, RTTY,
digital modes or FM, with no time limit.
Other Alpha products available to enhance your use and enjoyment of the 8410 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.
1.2 Amplifier Capabilities
CAUTION:
It is extremely important to thoroughly review the Installation and
Operation sections of this manual before attempting to us the Alpha
8410. Failure to do so could result in serious damage that may not be
covered under warranty.
ontinuous RF Output. The 8410 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.
ompatibility with popular amateur transceivers and exciters. The 8410 requires
approximately 50-65 W peak RF drive for 1.5 kW output.
apable of full W 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.
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1.3 Shipping Information
The Alpha 8410 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. ontact Alpha at 303-473-9232
for shipping advice and assistance.
1.4 Safety Information  Installation and Operation
Make sure the Alpha 8410 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 8410 weighs approximately 70 pounds when the transformer is
installed. Use proper lifting techniques and two people when moving the
amplifier. Note that amplifier should NEVER be transported with the transformer
in place.
The Alpha 8410 is designed to meet international safety standards and F
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 8410 amplifier.
Warnings: What Not to Do
Never open the amplifier case without unplugging the unit from
the wall outlet.
Always resist the temptation to immediately hit the ON button after
the amplifier faults to power off.
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.
Never allow liquids to enter the amplifier through the cover holes.
Never stick objects into holes in the case.
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.
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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. lick
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
FAQ’s
Alpha Forum
You can email us for customer support at [e-mail] or
you can send your request by fax to 303-473-9660, or call us at 303-473-
9232
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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 8410 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 ustomer 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 8410 amplifier. If you are unsure of any of these
items, please read the noted sections carefully.
2.3 Preparation
__ 240V A 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)
2.4 Unpacking
__ Unit hecked for Damage?
__ Transformer Installed? (Section 4.2.1, 4.2.2)
__ Power ord onnector Attached? (Section 4.2.3)
__ A Primary Voltage Set? (Section 4.3.6)
___Amplifier Grounded Properly? (Section 4.4.1)
__ Amplifier over Replaced and Secured? (Section 4.3.6)
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2.5 Operation
__ All Exciter Interconnections Set? (Section 6.2)
__ Exciter Drive orrectly 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 8410 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 A circuit. If you do not have
a 240V A 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
240V 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 8410. 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 8410
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 8410 can run
when connected to an 120V A outlet. However, you WILL NOT achieve full legal
limit output in this case. If the amplifier is connected to an 120V A outlet, you should
not expect more than 1000 W output.
3.3 Air Flow
It is critical that airflow around the Alpha 8410 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.
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Figure 3.3 -Minimum clearance for proper airflow
Poorly designed consoles can 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. 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
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Make sure the exhausted air
cannot be recirculated back
into the amplifier air intake.
Too ensure adequate cooling,
make sure the top and rear of
our amplifier have at least 3”
of clearance to allow
unobstructed airflow.
Keep rear intake clear
Keep top tube exhaust clear

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. orona 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”, 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. lean 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. Support the coax
frequently using non-compressive clips so that it does not hang or stretch under its own
weight. Avoid sharp or kinked 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 F requires users to check their installations for compliance with published values
for allowable exposure to RF fields. This information is available in ARRL publications,
F 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.
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If you have any questions regarding engineering your 8410 into your amateur radio
station, please visit our online technical support website at:
www.alpharadioproducts.com
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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. ontact 303-473-
9232 if shipping damage is found. arefully unpack the amplifier and transformer.
arefully remove the amplifier and place it on a workbench or table where you can install
the power transformer.
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 8410 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 ground connection
on the rear panel ground terminal.
Make sure all F cables have a solid ground shield in place.
WA NING!
The transformer is very heavy and must be moved with due caution using
only the lifting handle.
CAUTION:
P OCEED SLOWLY to avoid bumping and damaging adjacent wires,
connectors or components.
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While the top cover is removed, make sure each tube is firmly seated in its socket, rubber
exhaust chimneys are fully and correctly installed, and anode connectors are tightly
clamped to each tube. The silicone rubber chimneys installed on the VTX-X118 tubes are
a critical part of the cooling system. Make sure the chimneys are straight and fully
installed so the bottom of the chimney is firmly against the tube deck and completely
covers the airflow openings in the deck. Make sure that the silicone rubber chimneys are
flush with the top cover when it is placed back on the amplifier. Tube cooling exhaust
must exit only through the tube anode fins; it must not be allowed to escape outside them.
Failure to ensure proper cooling airflow may result in tube damage or destruction, which
is not covered under warranty.
4.2.2 Connecting the Transformer Power Plugs
onnect the 9-pin white Molex connector to the matching plug mounted on the
back wall of the amplifier
onnect the 8-pin orange connector to the matching pins on the upper (Mains)
P B.
onnect the 6-pin yellow connector to the matching pins on the lower (HV) P B
heck to ensure that all connector pins on these three connectors engage fully and
correctly.
4.2.3 Power Cord Connections
WARNING!
To avoid the hazard of a potentially fatal electric shock and/or
severe damage to the ALPHA 8410 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 and power receptacles for 190-250V
circuits.
ALWAYS use grounding type A connectors which conform to local codes and
ensure that the green wire in the Alpha 8410 power cable is wired only to the A
mains safety ground (or to neutral, as may be necessary with a 240V circuit
configured 120V-N-120V without a separate ground, commonly found in the US).
The green conductor in the power cord is wired to the ALPHA 8410 chassis. It MUST be
connected only to the power source safety ground or neutral. The black and white power
cord wires connect to the two “hot” wires of the A source; either wire may be connected
to either side of the line. For best results use a dedicated 200-240 V branch circuit of #10
AWG copper wire or equivalent, rated at 20 A, to feed the amplifier.
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4.2.4 Important Information about Operation from 90-130V AC
Electrical power equipment will draw twice as much primary current from 120 V
mains as from 240 V mains. Therefore, operating the ALPHA 8410 on a typical 120 V/
20 Amp household circuit without exceeding the 20 A circuit rating will limit
maximum peak power output to about 6001000 W. Maximum possible RF output
power for any particular primary A voltage and current capacity may be estimated as:
P max = (V x I ) / 2.3
lineline
For example, if the Alpha 8410 operates from a circuit that is capable of delivering 120 V
A at a maximum current of 20A, with no other loads connected to the circuit, maximum
peak RF output possible without tripping the 20A breaker (or fuse) is approximately:
Po max = (120V x 20A) / 2.3 = 2400/2.3 = 1043 W
If the same circuit also supplies a transceiver drawing peak line current of 5A and a lamp
drawing 1A, only 20-5-1 = 14A is available for the amplifier and maximum possible
output is about:
Po max = (120V x 14A) /2.3 = 1680/2.3 = 730W
Below are some considerations at the high end and the low end of this voltage range that
are rarely encountered.
Low Voltage vs. Power Output At the low end of the voltage range, do not expect to be
able to get 1,500 watts output if your line voltage is below 120 volts. If your line voltage
is between 110 and 130 volts, then 1,500 watts PEP operation ( W or SSB) may be
possible if your A line service has sufficient current capacity (30 amp circuit
recommended). However, 1,500 watts continuous should not be expected. If your line
voltage is between 90-120 volts, then power outputs above 1,000 watts should not be
expected from the amplifier. Tune (adjust) the amplifier for no more than 1,000 watts
output, and simultaneously for maximum efficiency.
placed where normal air flow is restricted because the cord could overheat. If other
equipment is drawing current from the same circuit as the Alpha 8410, then the
considerations in section 4.2.3 should be taken into account.
High Voltage and Tube Life At the high end (sometimes encountered when using poorly
regulated generators) the plate voltage and tube heater voltage may be too high. If
voltages above 250 volts are applied for any length of time, the lifetime of the tubes may
be reduced. If this is your situation, the first line of defense is to contact your utility
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company and ask if they can reduce your line voltage. If this is not possible, you may
want to consider placing your own step-down transformer in line between the A outlet
and the amplifier. If this is necessary, a transformer with at least 4-kVA rating is
required, due to the nature of the current waveform in the primary. Another choice for
voltage control, a ferro-resonant voltage regulator, is an expensive solution, but is a good
way to stabilize primary voltage.
Note: If you intend to operate the amplifier on any of the 90 - 130V settings, the lower
2 amp fuse on the rear panel will have to be changed to 5 amp. to allow for the
increased in-rush current.
FIGURE 4-2-1 Amplifier Interior
0 V
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Transformer Relay and
AC tap PCB HV AC Transformer
Input AC safety Switch
AC Transformer Molex
HV Safety Switch
Cooling Fan
Output RF Connector
Input RF Connector
Tube Parasitic Choke
attachment point
VTX-X118 Tubes
Output Tank Circuit

FIGURE 4-2-2 Amplifier Rear
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Air Inlet RF InputKey line Input/Output RF Output
AC Cord USB Input AC Fuses
Chassis
Ground

Figure 4-3 AC Power Setting
With the top cover removed, the primar voltage taps are located on the top of
the Mains Board, which is between the transformer and the front panel. There is
a row of 5 “fast on” connectors (J1 through J5) and a “fl ing” jumper connector
which mates with them. See Figure 4-3 above. There are 5 “nominal” primar
voltages, which cover all the line voltages normall encountered around the
world. Selecting the appropriate tap for our situation will optimize amplifier
performance, safet and lifetime. The nominal mid-range voltage for each tap is
printed on the Mains Board circuit board. These voltages are 100,120, 200, 220
and 240 Volts. The acceptable line voltage for each tap is the center voltage plus
or minus 10 Volts. One of these taps is suitable for an of the “nominal” line
voltages encountered worldwide.
CAUTION:
When using any high power amplifier, failure to connect ALL station
equipment to a good common ground may allow RF feedback to leak into the
transceiver and cause severe signal distortion.
20
Input AC tap settings
can be made by moving
the flying lead to the
marked AC spade posts
marked in the
appropriate voltages.
The proper taps must be
made before the AC
power is applied. When
making changes make
sure the amplifier is
unplugged.
Never use a tap other
than the proper voltage
or damage to the tubes
and amplifier will
result.
Flying lead attachment points.