Gemini HF-1K is a solid-state 1kW 1.8MHz – 50MHz power amplifier with additional capability at 472kHz. It uses a single dual-LDMOS power device for reliability, and has an internal highly reliable low-noise switching power supply, in order to reduce the overall weight. The thermal design is very conservative with a large heatsink, and OFHC heatspreader. This, assisted by several fans and a sophisticated thermal management system, allows the channel temperature of the LDMOS device to remain within limits which should ensure extended life, even with heavy usage.
A major objective of the RF design has been to significantly exceed the spurious signal generation requirements of the international approvals standard (ETS 300 783 pts 1 and 2) for amateur radio equipment. To this end the Gemini HF-1K has more extensive filtering than is usual in HF PAs. While LDMOS power FETs are amongst the most rugged RF power amplifier devices currently available, they are sensitive to RF overdrive. The Gemini HF-1K has both extensive monitoring to minimise the risk of damage by overdrive and a conservatively designed input circuit. Following modern industrial practice, the Gemini HF-1K employs full touch-screen control using a 480 x 272 pixel 41⁄4 inch full colour TFT display. A wide range of monitoring functions can be displayed, including power output, PA drain current, VSWR, heatsink temperature, and linearity. The latter parameter provides a graphic indication of when the amplifier power output enters the region where ‘splatter’ will be generated.
As with other Linear Amp UK designs, there is no provision for ALC, as this is a major cause of bad signals. While the control system provides for manual band selection, it will interface seamlessly with standard CAT systems. The presence of valid in-band RF signals is also detected and will initiate switching automatically to that band. A high-speed, very low distortion, PIN diode, solid-state switching circuit allows very fast full break-in operation. A single input and three selectable antenna output connectors are provided. The latter can be preset on a band by band basis.A 0dBm SMA feedback output is provided to allow connection to transmitters with linearisation capabilities. The amplifier is built in a very robust all aluminium case. A modular assembly approach has been adopted with non-RF and high current DC interconnects being distributed as a single bus.
ACOM 2020S HF Linear Amplifier The ACOM team, are proud to introduce the brand new 2020S. Solid-State 1500 W: 1.8-54 MHz Linear Power Amplifier with Touch-Screen Remote Control.
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(Also read : http://www.cqdx.ru/ham/qro-qrp/om4001a-hf-linear-amplifier/)
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