QSK for the linear amplifier
I wanted full QSK in the big amplifier. QSK, also known as full break-in, allows the transmit/receive switching system to operate fast enough that you can hear between the dits and dahs while sending CW. Once you get used to it, it is difficult to go back to conventional semi break-in operation. Achieving full QSK requires very fast relays and, in many cases, a sequencer to ensure that all relays have settled before RF is applied. To find out what would work, I measured a large number of relays that I had available and compared their switching times. The goal was to determine which relays were fast enough for reliable QSK service. Below is the result. One thing worth noting is that relay speed can often be improved by driving the relay coil with a higher voltage than its nominal rating. This is a commonly accepted practice, provided that a suitable current-limiting resistor is placed in series with the coil. Relays tested. Interesting was that Omron G2-RL relays was very fast with...