I've decided to build a 6 metre band transceiver. My thoughts so far is that it will be Single Side Band (USB) only and cover the band's lower portion of 50-52 MHz. It will have an I.F. system based on a surplus 9 MHz crystal filter. Output power will be 15-20 Watts PEP from a Mitsubishi RF module and more than enough to drive my Tokyo HL-1K/6 linear amplifier up to its maximum power of 550 Watts if required.
The digital VFO has been built and operates from 41 - 43MHz. Also built now is the 9 MHz SSB generator and 9 MHz transmit I.F. amplifier and mixer. I built a 3 or 4 versions of the latter to try different bandpass filter designs to see which one was most suitable for low side injection ie. 41-43MHz. I settled on a three stage capacitor coupled Chebyshev circuit which has a steep skirt on the low side and attenuates the LO frequency by the greatest amount.