Notes for the Solid State 250W 160-6m Linear Amplifier

 The 250W solid state amplifier schematic was originally drawn as one schematic with five pages, so all the part designations were unique. When the schematics were redrawn in ARRL format for use in the 2010 Handbook, they were separated into four individual schematics, each with its own reference designators. The parts lists given here in the Excel spreadsheet format use the part designations from the original drawing. For this purpose, the original schematic is also included here, in ExpressPCB format, along with the parts listing by page on an Excel spreadsheet.

  The schematics and PC boards were laid out using ExpressPCB. Go to their web site, http://expresspcb.com/, and download their free software. This easy-to-use software will provide access to the schematic and PC layout files and will allow modification of the layout to suit your needs or make substitutions for parts on hand. The board set must be ordered from ExpressPCB. This is the tradeoff for having free schematic and PCB layout software. They are not cheap, but of the very best quality and can be had in as little as two days.

  The PC boards have been laid out as a single board that must be sheared into three separate boards – PA, LPF and Control. This saves money because 80% of the board cost is in the setup fee. To increase the number of boards is very inexpensive once the setup fee is covered. As long as the total board area does not exceed their maximum limit, individual boards can be pasted together into a single board to be separated later. This was done here. Even so, two boards, the minimum order, with solder mask and top side silkscreen costs $302.

  This is not a Heathkit. The amplifier in this article is intended as a teaching example for the circuits used and design concepts presented. The information given here is enough for a competent and experienced technician to duplicate the design. Extensive use is made of surface-mounted parts. It is not a suitable project for the beginner.
 
       Dick Frey, K4XU        July 17, 2009