KN4BXH

Objective: I have a Kenwood TS-700SP that produces 10w of power that is not adjustable. I have a VHF amplifier that wants 1-4w in to produce 80w-120w out. A simple coax attenuator would work but it would attenuate the transmit power and the receive. Since attenuating the received signal is not want anyone wants, I needed a way to attenuate the transmit power but not the received signal. Tom Morgan, K4VCM, gave me the idea of installing the attenuator inside the amplifier. With the attenuator installed in the amp, between the relays, it would accomplish the attenuation during transmission but not while receiving. I used a Pi attenuator calculator to give me the values of the resistors that I needed. Then I used a magic marker to draw the circuit onto a PCB then acid etched the PCB to eat way all of the copper except where the magic marker was.

So I decided that I wanted to do some SSB work using my old Kenwood TS-700SP. The radio is an all mode transceiver that puts out 10W only. I want to get a VHF amp to get my power to somewhere around 100W. Later I will describe how I accomplished that but for now I'll focus on the Yagi. I used VK5DJ's antenna calculator that can be found here:  http://www.vk5dj.com/yagi.html Then I graphed the antenna using EZNEC that can be found here:  https://www.eznec.com/ After I used the calculator to give me all of the measurements I designed the cross members for the antenna and used my 3D printer to make them. I also designed end caps to keep the elements water tight. Here is a close up of one of the cross sections: I mounts the 3D printed parts to the boom. I use a boom that is 1-3/4" in diameter and roughly 14' long. The antenna elements were recycled from a Mosley antenna that was bent up. I cut the straight sections and was lucky that I had enough.