I was given this kit by Wal, VK4CBW, as he had purchased it some years ago and knew he would not get around to building it.
The kit was produced and sold by http://www.hfprojects.com in America and came well packaged in a series of sealed plastic packets. Everything including the enclosure and heavy duty heat sink were included.
This little amp requires 1W drive for 30W output and features a Mitsubishi RF mosfet module mounted on the heatsink. There is also a filtered Anderson Power Pole DC input that takes 12V at around 6.2A. And measuring only 5.25 x 3 x 3 inches and weighing less than 1 lb, I figured it would be perfect for SOTA or VKFF operations.
I started my working on the well-made PCB.
Then I began making the power cable assembly, the RF cable assembly and the switch cable wiring.
I had to fabricate a make-shift mounting plate for the Anderson Power Poles as this was missing from the kit. It has been ordered but hasn’t arrived yet. Eager to avoid delays so I could catch the 6m band opening, I made a replacement out of PCB material.
After a little fiddling it went in well and did the job.
Next, the circuit board and amp module were installed and the initial check carried out.
The bias current had to be set to 0.7A if the amp is to be used for SSB work, or 0.5A for FM. I chose the former.
I skipped the next step, which was to align the low pass filter as I don’t have the correct instrumentation. But as I had constructed coils L1 and L2 according to the instructions, this wouldn’t be too critical.
The power output test was more important. I connected the amp up to my Yaesu FT-817 (with power wound back to 1W) and attached my homebrew dummy load and an SWP/Power meter. RF output was shown to be a mere 16W. So I flicked the bypass switch and measured the output as 1W with an SWR of 1.0:1. All good there.
Tweaking the coils of L1 and L2 soon produced the required 30W, so it was time to disconnect the dummy load and attach my 6m monoband dipole antenna.
Keying down produced the power output reading I was after.
Next, I attached my LDG auto tuner to the chain and was ready for an on-air test.
The result was most pleasing. I worked a bunch of VK7 stations (SSB and CW) and well as VK2s and 3s. I am in business and ready to take advantage of the summer openings.
Oh, and all reports received were most favourable. Nice clear signals, good reports and clear audio were what most operators reported back: they were all impressed that I was only using 30W – most stations were in the 200-400W range.