Member project · HF amplifier

EVQ100 HF 40m Amplifier

A low-cost HF linear amplifier built around the IRFP150N power MOSFET. The device gives plenty of output on 160, 80 and 40 m — this version is made for 40 m, where most Indian (VU) hams ragchew and where popular QRP rigs such as the BITX40 and uBITX perform well. The aim: a simple 40 m amplifier that makes your signal big without emptying your pocket.

  • 90–130 Wpeak output after the LPF
  • 5–12 Wdrive at 50 Ω
  • 13.8–18 VDC supply
  • 40 mthis version only
EVQ100 HF 40 m amplifier – front panel with power switch, cooling fan and DC power leads

EVQ100 specifications

Band40 m only (this version)
Active deviceIRFP150N MOSFET
Supply voltage13.8–18 V DC — a 20 A SMPS will do the job
Drive power5–12 W at 50 Ω (ideal for BITX rigs)
Peak output90 W at 13.8 V to 130 W at 18 V, after the low-pass filter
Output impedance50 Ω
VSWR1:1.2 at peak power, with a well-matched antenna
FilteringBuilt-in 40 m low-pass filter

40 m only. Match the antenna for the lowest possible SWR before running full power.

  • Built in

  • Reverse-polarity protection
  • Cooling fan
  • Thick aluminium heat sink to carry away the MOSFET's heat
  • Easy to service if anything goes wrong

A closer look

EVQ100 40 m amplifier – angled view showing the top-mounted cooling fan EVQ100 amplifier – side view with the finned aluminium heat sink EVQ100 amplifier – rear panel with the RF input and antenna connectors

On the air

VU3EUE

OM Shanavas, VU3EUE, from Kozhikode is QRV on 40 m with an EVQ100. Questions about the build? Ask in the comments below.

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3 Comments

  1. I have not seen its performance but I think it will be suitable for my set mbitex collected from Lamakan meet.
    VU 3 IBC
    Puducherry.

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