I purchased the SB-220 & SB-221 manuals so I would have a reference for the parts needed to convert the HL-2200 to 10 meters.  I saw an SB-221 conversion kit from Heathkit on eBay once but was outbid on it.  That kit would probably contain all the parts necessary for the 10 meter conversion of the HL-2200. I found the SB-220 switch assembly at the Dayton Hamfest this year, 2004.  I did not need the back ceramic switch and 80/20 meter plate coil because it is the same as the HL-2200. The HL-2200 plate switch has the extra position needed for 10 meters, it is not used.  The front input coils and switch were needed  from an SB-220 to complete the conversion.  The 80, 40 and 20 meter input coils are the same as the SB-220.  The 15 meter circuit is formed by by 3 coils, one is the same as the SB-220 15 meter circuit. It also uses 2 additional coils to form a 10 meter trap to prevent use at 11 meters.  The irony of this is that anyone could strip out the 2 additional coils and a couple caps and the trap is gone.  The HL-2200 input switch does not have the 10 meter position needed on the ceramic switch.  I'm sure if you looked around you could buy a new one but I am not aware of it. Your best bet is an old assembly out of a SB-220 that someone has converted to 6 meters or above.  You will also need to tap the 15 meter plate coil with silver plated strapping and connect it to the 10 meter position on the plate switch.  This is the high powered area so the strapping needs to be wide enough to handle the circuit requirements.  Nebraska surplus has the silver strapping necessary for the conversion.  I have listed their WEB site on my KC8RP page.

I have included a PDF file you can download which contains the parts lists, schematics and misc. pictures from the HL-2200 & SB-220 manuals.  The PDF file is set up so that the first part up to the schematic is the HL-2200 and the second part from the second schematic to the end is the SB-220.  Let me know if there would be anything else of help.

The flashover protection plus other good mods. are in CQ September 1992. The relay modification manual is available from my manual list.  The Harbach soft start module is the SB-220 version which works on the HL-2200.  See the Harbach link on the KC8RP page.