Hardrock-50 Builders Information Site


Welcome to the Hardrock-50 power amplifier site!

The Hardrock-50 is a complete 5W in, 50W out power amplifier kit. The HR50 is FCC Type Approved for commercial sale and can be purchased at HobbyPCB.com. The HR50 uses 4 Mitsubishi RF16HHF1 power MOSFETs and microprocessor controlled for easy reliable operation. The amplifier is based on Jim Veatch's award winning design developed for the ARRL's 2nd Homebrew Challenge competition and was tested extensively by the ARRL labs for output power, linearity and durability. More than 800 kits have been sold and builders receive excellent support and resources to successfully complete the kit. 

The HR50 interfaces with popular QRP transceivers like the HobbyPCB RS-HFIQ,  Elecraft KX2/KX3, Yaesu FT-817 and Flexradio Flex-1500 to provide additional power when necessary or to act as an intermediate amplifier for driving even higher power amps. The HR50 can be fitted with a 0.5W input 5W output driver amplifier that fits inside the case and integrates seamlessly with  HR50's operation allowing it to work with low power SDR kits like the Softrock, Omnia SDR and others. For CW operators a QSK board is available that replaces the electromechanical relay with fast, silent PIN diode switching. You can even install a wide range, automatic antenna tuner inside the compact case to create a truly portable QRO solution.

Have a look at the reviews on Eham.net (opens in a new window).



Frequency Range

160, 80, 40, 30, 20, 17, 15 meter Amateur Radio Bands

60M is available when the ATU is installed

12, 10 and 6M may be added by licensed Amateur Radio Operators

Input Power

5W maximum, typically 2-3W

Output Power

50W nominal, 35W on 6M

DC Power

11-16 Volts, 10 Amps typical, 12A maximum

Keying Modes

Stand-by, Carrier Operated, Push-to-Talk

Input/Output Jacks

UHF Connectors


4.25” W by 3.5” H by 7.5” D

(133.4mm W by 88.9mm by 190.5mm)

(not including switches and connectors)


3 lbs (1.4 kg) 3.5 lbs (1.7kg) with ATU


The Toroid Guy now offers pre-wound toroid kits for the Hardrock-50

For $35 you can get a complete set of prewound toroids for the Hardrock-50. It includes L6 thru L15, the next time I have to build one of these, I'm ordering a set! Ordering infor is on the Toroid Kit page.

Thanks to Mychael for providing this excellent service for us.