By Peter Hart, G3SJX, and reproduced by kind permission of the RSGB.
"ACOM is a name which is probably new to most readers. Established in 1988, and based in Bulgaria the company specialises in developing HF power products for commercial, government and amateur markets. In 1999 Acom launched its 2000A high-power automatically-tuned HF linear. First unveiled at the Dayton Hamvention in May of that year, this 1.5kW amplifier has been acclaimed by many top DXers and contesters as the best on the market. Similar in many respects to the Alpha 87A, it has more features, is significantly cheaper, and yet an equal to Alpha in terms of quality of design and construction. More recently, ACOM launched its 1000 amplifier, a manually-tuned amplifier for 1 kW output and covering all HF bands plus 6m. I was particularly pleased to obtain the first production sample for review. Although Acom amplifiers have been available for only a couple of years, the fruits of its handiwork have been visible for much longer in the Alpha 91b, which was entirely developed and manufactured by Acom under contract from Alpha. This amplifier was one of Alpha's more popular and successful. [a review of Alpha amplifiers by Peter Hart appears in the February 1997 RadCom - Ed]
Both Acom amplifiers are based around the Gu74b / 4CX800A ceramic-metal tetrode which is available at very low cost compared with the 3CX series of ceramic triodes or the glass 3-500. These tetrodes need very low drive and have excellent distortion characteristics. Both amplifiers are manufactured in Bulgaria from parts sourced in Eastern Europe (please see note below) and this results in a top quality amplifier at a very attractive price.
We will post the text of the 2000A review on here soon.
We have some corrections to the review, which, although they were accepted by the RSGB, did not meet the publication deadline
1. In the introduction to the review Peter Hart states "Both amplifiers are manufactured in Bulgaria from parts sourced in Eastern Europe and this results in a top-quality amplifier at a very attractive price." ACOM have asked us to make clear that the vast majority of components are sourced from Western components producers. The vacuum tubes used - 4CX800A's - are made at the Svetlana factory, in St Petersburg, Russia (the oldest vacuum tube factory in the world). ACOM produce the bandswitches and variable capacitors for the tank circuits at their own factory.
2. In the description of the ACOM 2000A, the QSK is discussed "The amplifier follows well in QSK operation but the relays are quite noisy. They would benefit from the same mounting method as adopted in the 1000." In fact the ACOM 2000A reviewed was an early model and the current units use the same rubber-mounting method as used in the ACOM 1000.
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