Info on Elecraft’s KPA1500 and KPA 800 HF/6 Meter Amplifiers.

As of late November, 2006, Elecraft was awaiting FCC approval before beginning production.  Shipping was expected to begin in January, 2007.
Here are the first published pictures anywhere on the Internet of the insides of the Elecraft KPA1500 and KPA800!

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These are the prototypes of the KPA1500 (left) and KPA800 (right, upside down).  The KPA800 was turned over so that it could be opened up.


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Another shot of the amplifiers.  The KPA1500 is sitting on top of its companion external power supply.  The KPA800 has its power supply internal.


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This in the underside of the KPA800 showing the RF deck, low-pass filters and antenna tuner.  The KPA1500 is similar except that there is another RF deck on the top side of the radio, facing up.


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A different view of the RF deck of the KPA800.  There is a large heat-synch on the other side of the board.


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Here is a close-up of the 8 finals in the KPA800, arranged 4 on each of two field-replaceable, plug-in boards.  The KPA1500 has 4 such boards for a total of 16 devices.   The RF power MOSFET’s, APT ARF463A/B’s are each rated at 100 Watts “key down” output and dissipation of 185 Watts.  Complete specs for the finals are at:

http://www.microsemi.com/datasheets/ARF463AB.pdf

The KPA’s run 60 volts on the finals, which is conservative since the ARF463’s are rated to operate at 125 volts.  Final efficiency is about 50%, which is normal for a broad-band, solid-state linear amplifier.  Running at rated power, these finals are loafing in the KPA800 and KPA1500!