Owners of Drake L7s can benefit from the following 10-meter adaptation. Proceed with the following steps while using the owner's manual for reference. Replace the low-pass filter with a short piece of RG-58 coaxial cable. Later models have a shorting path on the low-pass filter board identified by empty terminal lugs at the input and output. On these units simply switch the input and output coaxial-cable center conductor to these empty terminals. (do not short the input to the input of the low-pass filter). Doing so does not remove it from the circuit.)
Removal of the band stop from the band switch is the next step. On early models this was a removable stop located on the back side of the index of the band switch and may be found at the rear of the input matching filters. Use a sharp, pointed tools to rotate the nut on the stop and then extract the stop. Add two 68-pF DM19 or DM20 mica capacitors to the input coil assembly. One is wired to the across the input wafer. The other is connected to the input side of the 15-meter input coil. With the linear amplifier placed upside down, observe that the 15-meter coil is the one farthest toward the back and on the left. The input side is the bottom end (closest to the clip).
Returning of the 15-meter input coils may be necessary. Use the input-coil adjustment procedure outlined in the manual. There is no tuning for 10 meters. - Jeem Newland, WB8RXI, Miamisburg, Ohio