HARDROCK-50 HF Power Amp Kit

| abril 27, 2014

HARDROCK-50 HF Power Amp Kit

The HobbyPCB Hardrock-50 amplifier is supplied by the manufacturer in kit form only. The kit consists of three printed circuits boards with surface mount parts installed, all thru-hole parts required to complete each printed circuit assembly, an extruded aluminum chassis with machined and etched endplates, all chassis electrical and mechanical components and complete assembly and alignment instructions.


Frequency Range: 160M – 1.8 – 2.0 MHz

80M – 3.5 – 4.0 MHz 40M – 7.0 – 7.3 MHz 30M – 10.1 – 10.15 MHz 20M – 14.0 – 14.35 MHz 17M – 18.068 – 18.168 MHz 15M – 21.0 – 21.45 MHz

Type of Emission: Determined by the device driving the HobbyPCB Hardrock-50.

Operating Power Level: 0 – 50W maximum

Power Source: DC Power Supply +13.8V @ 10A (typical)

Unit Tested: Prototype

Equipment Type: Fixed

HARDROCK-50 HF Power Amp Kit HARDROCK-50 HF Power Amp Kit

Other Information

The HobbyPCB Hardrock-50 operates only in the amateur radio bands below 22 MHz. The amplifier is not designed to operate on any frequency outside of the amateur bands below 25 MHz. Lowpass filtering on all bands reduced the gain of the HobbyPCB Hardrock-50 to 0 dB or below on all frequencies above 25 MHz including 26 to 28 MHz.

The HobbyPCB Hardrock-50 typically requires 5 Watts of drive to obtain full output power depending upon which transmit band it is on.

The gain of the HobbyPCB Hardrock-50 designed to be less than 13dB on all bands under all conditions and the maximum measured gain is less than 12 dB.

In ‘off’ or ‘standby’ positions, the HobbyPCB Hardrock-50 does NOT amplify. The exciter energy is simply passed on to the antenna at the same level in which it entered the amplifier. Since this switching is accomplished with an electromagnetic relay, not solid state components, the spurious emissions of the transceiver are unaffected.

HARDROCK-50 HF Power Amp Kit

HARDROCK-50 HF Power Amp Kit

he HobbyPCB Hardrock-50 output power will not exceed 80 Watts into 50 Ohm resistive load. Final Amplifying Devices: Quantity 4, Toshiba RH16HHF1 power MOSFETs Power into the drain of each device: 13.8V X 2.5A = 34.5 Watts Total power input to the RF amplifier stage: 4 X 34.5 = 138 Watts Note the power delivered by the bias supply is negligible.

The HobbyPCB Hardrock-50 RF amplifier is not capable of amplification in the frequency band 26-28 MHz. Significant changes in the output filter bank and firmware would be required an therefore the HobbyPCB Hardrock-50 cannot be easily modified to operate in the 26-28 MHz frequency band. Driving the HobbyPCB Hardrock-50 in the 26-28 MHz frequency band results in -6 to -20 dB gain, depending on the actual frequency applied, from input to output of the amplifier when the Hardrock-50 amplifier is active and a gain of less than 0 dB when the Hardrock-50 is in stand-by mode or powered off.


Operating Instructions:

1 – Set power switch to ‘ON’ position

2 – Press the Band + or – button to select the frequency band

3 – Select SB (Stand-by), CR (carrier operated) or PT (push to talk) keying mode


In Stand-by mode or when the power switch is in the off position the RF input and RF output jacks are connected together and the Hardrock-50 amplifier is bypassed.

When the Hardrock-50 amplifier is powered but not keyed, the LCD displays the selected band and operating mode, input voltage and heatsink temperature.

When the Hardrock-50 amplifier is powered and keyed the LCD displays the average forward power, the peak envelope forward power, the reflected power and the calculated VSWR.

Tune Up Procedure:

1. Select the proper band and operating mode on the Hardrock-50 amplifier and the exciter.

2. Adjust the output power level on the exciter not to exceed 5W into the Hardrock-50 amplifier and not to exceed 50W peak envelope forward power out of the Hardrock-50 amplifier.

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