A: The KPA1500 is our 1500 watt PEP output, MF, HF and 6 Meter linear amplifier. It utilizes the latest LDMOS transistor technology to provide a robust desktop amplifier in a compact cabinet, with an included companion power supply that can be located off your desktop. The KPA1500 was designed with the serious operator in mind. Its no-nonsense front panel shows all important parameters at a glance, with a high-contrast 32-character LCD and fast, bright LED bar graphs. Band switching is instantaneous, via control inputs or RF sensing. Protection and monitoring circuitry is extensive and foolproof, letting you focus on the job at hand — breaking pileups and overcoming the most difficult operating conditions. And it wouldn’t be an Elecraft amp without robust PIN-diode T/R switching. Like our KPA500, the KPA1500 offers fast QSK without a noisy relay. The amplifier’s rugged internal ATU can handle full power with load SWR up to 3:1, while a wider matching range is allowed at lower power levels, including up to 10:1 in standby mode.

A: At this time, it's available in Factory-built form only.

A: The exact date will be determined when regulatory testing and certification (CE etc.) have been completed.

A: The photo below shows the front panel controls. Note that the buttons use Elecraft’s familiar Tap or Hold functions for access to the most-used features.

Additionally, there is a Menu system for tailoring the KPA1500 settings to match your station requirements. Most of these need only be set up one time.

Below is a photo of the rear panel.

A: The rear panel of the KPA1500 includes the connectors described below.

• USB: Provides a virtual COM port for use with KPA1500 Utility and other computer-based control programs.
• Ethernet: For local and remote operation applications.
• XCVR SERIAL: For connections to Kenwood serial and Icom CI-V data streams to determine band and frequency.
• TUNE: Input that allows the KPA1500’s ATU to interact with an Icom remote tuner connection, found on many Icom transceivers. Can alternatively be used as a low-current on/off control output.
• AUX: A 15-pin jack for use with the K3 or K3S for Enhanced Mode operation. This fully integrates the KPA1500 with the K3 or K3S.
• KEY IN: Used with any transceiver to key the amplifier. Pulling KEY IN to ground causes the KPA1500 to be placed in transmit mode. (Normally pulled up to 5 volts DC through a 10 K resistor.)
• ALC Out: Provides a negative-going voltage to transceivers that require this feature. Elecraft radios do not require ALC to operate properly.
• REM: A 12-volt input signal for use in remote operation applications. This signal can be used to power on/off the KPA1500 with 12 volts DC applied to this connection.
• Control: Contains signals for the amplifier to communicate with its separate power supply.
• HV Supply: High voltage / high-current cable for the amplifier. Nominally 50 V, 50 A.
• Ground: For attaching the KPA1500 to station ground.
• TX Sample: Provides a low-level KPA1500 TX RF signal for sampling use by transceivers that support closed-loop pre-distortion techniques, e.g., Pure Signal. This low-level signal is taken directly from the amplifier’s directional coupler.
• RF Input: Connects to your transceiver’s RF output.
• ANT 1 and ANT 2: Dual RF output ports. When used with the internal 1500 watt tuner, the result of successful full-cycle tunes are remembered on a per-ANT port basis. This makes it easy to quickly QSY between antennas and recall the tuning elements needed immediately. Further, you can establish preferences for which ANT port to select when QSY’ing between bands. This allows you to pre-select what antennas you want assigned to each band.

A: Here is what the power supply cabinet looks like. It is the same size as the KPA1500 RF deck. There are three LEDs to show power supply operating status. The power supply can optionally be placed some distance away from the RF deck, e.g., on the floor or in any well-ventilated location. The standard power supply cable is 5.5 feet long.

A: Yes. The KPA1500 and the KPA500 support different customer needs.

A: Yes. Elecraft will continue to produce, support, and enhance the KPA500.

A: While the AC power cable is permanently attached to the power supply cabinet, the plug end is adaptable to work with NEMA 6-20R receptacles in various parts of the world. Depending on your location, you will need to install a suitable NEMA 6-20P plug.  Additionally, control interconnects cables, and a keying cable will ship with the KPA1500. The keying cable is an RCA-to-RCA cable for use with transceivers to enable the KPA1500 for transmitting.

A: Here’s an overview of the options:

A: Yes. The KPA1500 the internal tuner system is part of the amplifier. The KPA1500 is not available without the internal tuner. It uses the same proven low-pass L-network technology as other Elecraft automatic antenna tuners.

A: Yes. Each case measures 4.5 x 13.5 x 11.5 inches (41.5 x 34 x 29 cm) HWD, without fans, feet, and handle taken into account.

A: There are two cables connecting the cabinets: 1) A +52 volt DC power cable using high-current, high-retention-force Anderson Power Pole connectors at each end. 2) A control cable containing the signals needed for the RF deck’s microcontroller unit (MCU) to monitor and control the power supply.

A: The KPA1500 Control cables is 10 feet in length; suitable for use in a typical shack where the power supply may be placed in a more convenient location. The +52 volt heavy-gauge cable is 5.5 feet long.  An extra cable can be connected to extend the length to about 11 feet.  This is the maximum supported length for the Control and Power Cables.

A: You can specify the proper AC plug when purchasing the KPA1500.  The KPA1500 is shipped with a NEMA 6-20P plug. 

A: The AC cable itself is installed into the Power Supply cabinet. The other end will have a NEMA 6-20P plug installed. 

A: You should plan to have a 200-240 volt, 20 amp run from the load panel to the KPA1500.  Please tell your electrician to install a NEMA 6-20R type

A: The KPA1500 uses dual 1400 Watt LDMOS output devices configured in a push-pull output configuration.

A: Like all of Elecraft’s amplifiers, the KPA1500 uses PIN diode switching. This provides lightning-fast T/R while remaining silent, unlike less-reliable (and noisy) relay switching. To protect the amp and T/R switch, we use heavy-duty PIN diodes, very high reverse voltage, and virtually instantaneous detection of high SWR. All possible catastrophic load scenarios have been extensively tested.

A: The KPA1500 uses two dual-section LDMOS devices, operating at 52 volts nominal. The use of two devices rather than one allows for improved thermal transfer, as discussed in the next item.

A: The KPA1500 has a large, custom heatsink extrusion and thick copper spreader, both optimized for our packaging. We also use two LDMOS devices rather than one, allowing heat to be laterally distributed more efficiently. There are three large, deep fans. The center fan is controlled independently so it can turn on first, at a lower speed. In many cases that's all the operator will ever hear. Only during high duty-cycle operation are the other two fans turned on. We then carefully manage the speed of all three to minimize noise while still ensuring excellent thermal performance.

A: 30 minutes at 100%. This should handle most any transmission needs for amateur radio use.

A: 50 watts input, typical.

A: Separating the power supply from the RF deck provides three advantages: (1) This dramatically reduces the size of the RF deck unit, which is typically located at the operating position. The two units are both very compact, allow ease of installation and handling. (2) The separate power supply can be cooled optimally by its fans and thermal management system, without contributing heat to the RF deck. (3) All high-voltage AC circuitry is located within the power supply cabinet, making RF deck maintenance safer and more convenient.

A: Coupled from the amplifier output, the TX SAMPLE signal level will be compatible with Pure Signal requirements.

A: Yes, provided that a suitable external switching unit is used. SO2R, done correctly, requires extensive path shielding, switching components, and control circuitry. Adding these internally would have increased the size and cost of the KPA1500 for all customers.

A: Yes. The KPA1500 provides two user-programmable switch functions, PF1 and PF2, as well as up to 3 on/off control outputs. These could be used to control an external (third-party) dual-rig switch, antenna switch, SO2R switch, etc. The amplifier’s firmware will be updated as required. Also, the KPA1500 provides multiple serial interfaces for sequencing and automation via radios or computer software.

A: The KPA1500 can be used for MARS, Civil Air Patrol or other commercial applications requiring extended ranges outside of ham band allocations. Per FCC rules, however, the KPA1500 will not operate in the 11-meter band.   Generally, we recommend operating the KPA1500 at 1000 Watts or lower for MARS frequencies and we _strongly_ recommend the internal tuner be used at all times for MARS operation.   Plan on Training the Tuner on all MARS operating frequencies first before actual operation.  This makes QSY between assigned frequencies fast.

A: The KPAK3AUX cable kit provides all of the cables required. This cable kit will enable Enhanced Mode operation where the K3 or K3S can interact with the KPA1500 for fully integrated operation. For instance, the K3 or K3S can detect when the KPA1500 is in OPER or STBY mode and will adjust its RF output automatically to accommodate the lower RF drive required by the KPA1500. Then, it can return to ‘barefoot’ mode output when the KPA1500 is placed in STBY mode. Further, the band select buttons on the KPA1500 will control band selection on the K3 and K3S, since the radio and linear amp are in constant communication. Likewise, the internal tuner can monitor the VFO frequency of the K3 and K3S. This allows it to pre-select the tuning elements memorized from prior tuning cycles, supporting fast search-and-pounce operation.

A: The internal tuner in the KPA1500 will handle SWR levels inversely proportional to power output, primarily constrained by reflected power. That is, we rate the internal tuner at 1500 watts output while working into an antenna and transmission line system up to 3:1 SWR, and 500 watts at 10:1 SWR. When the amp is bypassed, the tuner can still be used just with the exciter, and the 10:1 limit applies.

A: The KPA1500 will try hard to work with high-SWR antennas. If the SWR is too high for your target power level, the amp will either drop back a few dB and keep on going or fault and go to bypass, depending on just how far over the allowed reflected power you get. The allowed forward power will vary with SWR. For the best transfer of RF power to the antennas system, plan on engaging the internal tuner when SWR rises above about 1.5:1.

A: Yes. With some antennas, this may provide a small improvement in signal strength, or better rejection of adjacent bands, due to an optimal match between the antenna and the transceiver.

A: Yes. The antenna tuner can be bypassed, separately from the amplifier itself, on a per-band/per-antenna basis.

A: The KPA1500’s antenna tuner provides over 1600 frequency “bins” to effectively cover the entire 160 through 6-meter range. Each bin can store as many as 32 separate tuning solutions for the antenna tuner’s L-network, for a total of over 51,000 tuning solutions. This allows rapid re-tunes even in the case where more than one antenna can be used on a given band.

A: There is no need to use a separate, external tuner since the KPA1500 already has an integrated, internal 1500-watt tuner.

A: Yes. The Elecraft K3 Remote System will be supporting the KPA1500 in future releases.

A: Please use this table to determine how you can hook up your radio.

• See notes below these tables defining Basic and Advance Mode operation.

Icom

Kenwood

Yaesu

Flex

A:  Elecraft has 2 ways for linear amps and tuners to work with any transceiver:  Basic and Enhanced Mode.  Here's what that means:

Basic mode connection uses only the KEY signal and RF from the transceiver to ‘arm’ the KPA1500 for transmit when the transceiver goes into transmit. This approach uses the KPA1500’s ability to read the RF frequency on the VFO dial as you just begin to transmit. Basic mode, therefore, depends on just a brief sample of RF in order to quickly and smoothly change bands.

Enhanced mode connection uses one of various communication interfaces to determine what the VFO frequency or band is before the transceiver goes into transmit. While the communication method varies by the maker of the radio, they all serve to tell the KPA1500 how to prepare itself prior to transmitting. For DXers and Contesters, you can move quickly between frequencies in the same band or QSYing across bands.

A: Yes. It has been designed to be operated remotely, supported by a variety of interfaces and a rich remote-control command set.  Elecraft has released a free Remote Control Windows-based app to completely control the KPA1500 from anywhere in the world. 

A:  No.  The only cables you may need will depend on the remote control approach you have chosen for your entire shack.