20W HF Amplifier with RD16HHF1 (K5BCQ’s kit) #1

Part 2 available here.

Looking for a HF amplifier for my FT-817 and some QRP home made rigs I have, I found this interesting kit from K5BCQ, a 160 to 6m amplifier with two RD16HHF1 transistors in A/B class. I ordered this kit from Kees, K5BCQ, a few weeks ago and these days the pack arrived in good condition. The kit price is quite reasonable, 50$ plus 7$ shipping to DX, and includes everything you need for the amp, except the LPFs and the enclosure, but for these two there are some hints on the schematic from the autor if you want to buy them elsewere. Also, I did not choose any heatsink option. My box height is not enough for those heatsinks that Kees offers.

K5BCQ 20W HF Amplifier Kit

K5BCQ 20W HF Amplifier Kit

The amplifier has a maximum input of 1W and there is also a place on the PCB for a “pi” attenuator with three resistors. In the pack supplied by K5BCQ there is a resistor set for a 3db attenuator, and if you don’t need any  power reduction a jumper can be placed instead of the series resistor, leaving the other two unconnected.

The quality of the PCB board is exceptional. And it is only 76 x 66 mm, which can fit easily to some computer’s CPU heatsink-fan systems. I will not use this setup, as I said before, the height of my box is 70 mm, so the board plus heatsink and fan will be to much, and I don’t like to put them outside.

K5BCQ Amp Kit PCB Top

K5BCQ Amp Kit PCB Top

K5BCQ Amp Kit PCB Bottom

K5BCQ Amp Kit PCB Bottom

The kit is powered with a common 12V power supply. The RD16HHF1 MOSFET transistors are rated 16W at 12.5V in the HF band and they have much better linearity then IRF510. Also their price is not so big. For a pair you pay 10$ at www.kitsandparts.com.

RD16HHF1 Transistors

RD16HHF1 Transistors

Amidon Toroids - 20W RD16HHf1 Amp

Amidon Toroids – 20W RD16HHf1 Amp

Coil Wires K5BCQ HF Amplifier Kit

Coil Wires K5BCQ HF Amplifier Kit

All in one I think is a good investment. I read good reviews from other hams who build similar projects with RD16HHF1 transistors. At first I had in plan to build a project with IRF530, but after building about 50% of it, I abandonned that in favour of this. I already ordered a 170x150x70 metal box for this project and I will put inside also a LPF with Amidon toroids. These days I will begin mounting the components and hope to do some tests.

Part 2 available here.

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5 Responses to 20W HF Amplifier with RD16HHF1 (K5BCQ’s kit) #1

  1. Razvan says:

    Ai terminat proiectul, cum merge ?

  2. Adrian says:

    Salut Razvan, inca nu. Din lipsa de timp merge cam greu. Intre timp am mai mesterit la cutie.

  3. Jeremy says:

    How’d this project turn out for you? I’ve just built a Peaberry SDR and at 1W maximum out, I’m interested in pairing it with an amplifier. I liked all the projects (and prices) on the K5BCQ site and now I’m looking to see what kind of luck others have had. Thanks!

    • Adrian says:

      Hi Jeremy,

      I haven’t finished yet. I plan to do it this next weeks. Set the bypass current, put some RF in and see what is happening. So far I did a power meter for, see my previous second last post, and the low pass filters.

  4. Steve says:

    I built mine and it is a very nice amp.
    the bias is easy to set and I built it in a small aluminum box with a computer heat sink.
    Tests out just fine at 20W.

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