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See Order Form for prices.                                 Schematic Diagram (66K GIF)

Build it! The TRI-POWER
Broadband Mobile RF Linear Amplifier
Detailed Construction Plans

Completely rewritten & redesigned for the
21st century. Now easier to build than ever!

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These photos show one of our finished amps, built by Lou Franklin
for mid-range RF levels (100W AM, 140W PEP/SSB), and using new
or readily available surplus parts.  Parts suppliers included in text.

We've sold plans for RF amps since 1979. Described here is the first major revision, and we’re really proud of it. The original plans were certainly OK, and worth the low price. Thousands were sold, and people liked them. But we’re always trying to improve our stuff. The original amp had a few design problems and used hard-to-find parts that made it tough for the average guy to build. Boy, we’ve learned a lot since then!

This new circuit includes parts values for three popular RF power levels, listed below. Each power option has been built and thoroughly tested. It's also easier to build now using currently available parts. Hundreds of happy customers have already written to tell us how smoothly this new version went together, and how well it works.

We’ve beefed up the whole instruction book to 28 pages. All professionally written and illustrated, in a style similar to this page you’re now reading. Why settle for a few pages of illiterate junk from other so-called "publishers?" Get the real thing for the same price! And as always, you get the CBCI promise of "Satisfaction Guaranteed since 1976."

How much will the whole project cost?  Including our plans and a 2-piece cabinet, the approximate cost is about $100.  The total depends on the power transistors you choose and the current price of gold, how good you are at shopping for parts, what parts you already have laying around, etc. This compares favorably to the typical "$1 per watt" price of ready-made commercial amps, if you could even find them.  But that $100 does not include the educational value of all you'll learn about RF design and HF radios!

OK, sounds great, but there is one drawback: You have to make the main printed circuit board (PCB) yourself, or give our templates to a professional board maker.   (There are lots of small firms that specialize in low-volume prototype PCBs; just do a Google search or check the back pages of electronics magazines. Heck, you'll love this amp so much you may want to make a bunch more for your radio friends!)  The last 4 pages of our plans include precise 1:1 PCB layouts and hole sizes, plus exact drill templates for the heatsink and cabinet holes.  Just tear off Pages 25–28 to keep them clean for the actual mechanical work and read the rest at your leisure.  And these 4 pages were specially printed at extra cost on single-sided paper and using a real offset press, not a photocopier. (In case you didn't know, hardly any copy machine can print at exactly 100%; they all tend to shrink or grow by 1% or so, which when making a PCB would be disastrous for the hole spacings!)

Broadbanded (3-30 MHz) push-pull design. No tuning required after a simple one-time setup procedure.
Three power levels: 60W-100W-120W AM/FM (100W-140W-180W PEP), depending on choice of transistors when building.
Now includes trimmer adjustable input and output tuned circuits for perfect SWR matching. Just set it and forget it.
All mode operation: AM, FM, CW, SSB.
Internal SWR protection with rugged Motorola or Toshiba transistors.
Bias switching lets you choose the most efficient method for Class C (AM/FM/CW) or Class AB (SSB) operation.
Carrier operated T/R relay with separate drop-out timing delays to automatically match AM/FM or SSB operation.
Switchable ON/OFF operation with LED indicator.
Jumper adjustable input network matches 4W-10W RF drive levels for most popular HF transceivers.
Transient spike protection in mobile use.
Double-sided PCB design for excellent RF stability and voltage regulation.

Not Legal For 27 MHz (Class D) CB Use
And it’s illegal to sell ready-made Linears or even amp kits in the USA. Please don’t ask us about them. The plans include reliable parts suppliers for everything you’ll need to complete this project, and have great fun learning too.

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