This year theBruce Kelley Memorial 1929 CW QSO Party will include 20 meters. I decided to see how my Push-Pull Colpitts does on 14MHz. It has a fairly good note and is very usable in the BK.
I wanted to stay with a high capacity tank circuit. This minimizes RF current through the tubes and should improve tone and performance. In addition, I wanted a number of turns in the tank coil so that I would have reasonable transformer coupling between the tank coil and the antenna link. I ended up with two 4 turn, 3" long coils wound on a 1.25" form. This 1.25" form resulted in more tank coil turns on 20 compared to the 2.5" form used for the tank coils on 40 and 80 and the antenna link coils. Tank capacitance is about 100 pF on 14 MHz. My Colpitts now runs at about 20% efficiency giving 2-3 watts output on 20 meters.
My 14 MHz CW Signal as recorded on July 22, 2020 using the Northern Utah WebSDR:
For comparison listen to this same transmitter on 80 meters:
I was licensed as WN6ULH in 1966. My first shortwave receiver was a WWII vintage variant of a National NC100A. As a novice I used
a military surplus BC-342 reciever and an Eico 720 transmitter. Then, when I left for college, I took a National NCX 200 transceiver
mounted under the dashboard of my 1965 Mustang. My stations since then since then have included a Drake TR4cw transceiver and
a Drake B line. Today my shack includes equipment dating from the early 30s through current gear operating CW, SSB and PSK31.
I've built many pieces of my own gear including tube and solid state transmitters and receivers.
My current interests include QRP operating, vintage home brew and the National Radio Company. Read more about these topics on
my web site at https://web.archive.org/web/20220604005204/https://www.prismnet.com/~nielw/wa5vlz.htm or emaill me at nwiegand0129@gmail.com.