HG-10, EICO 720, SC-40B
I was using Heathkit HG-10 VFO feeding the signal into Eico 720 transmitter and receiving the signal with Hallicrafters SC-40B for QRP QSO for about a month in the past. These are tube rigs in 1950s and 1960s.
I built a power supply to run the HG-10 VFO. I noticed the CW note was not clean and not stable(a bit chirpy and wabble) when I started using these rigs. So I up-graded and modified the homebrew power supply unit on the rectifying section and the filtering section.
Rectifying: I removed one single rectifying diode and installed a bridge rectifier to get full wave rectifying.
Filtering: I removed a resistor on the electrolytic capacitors and installed a chock.
I checked the wave being genarated with my oscilloscope and saw a fairly straight line and noticed good improvement on running HG-10 and Eico 720 for the CW note, not chirpy and not wobble either.
Some of my QSOs after this improvement made since April 22, 2006 are:
KA0YSV, N3EF/QRP, K8ZCT, KF0UU/QRP, W4VAH, KB2AMY, WB2AMY, WB2NVS, N2WJW, K3CB/M, KA3CFC/QRP to date (May 3, 2006).