Heathkit links parts for sale, service, modifications, stuff on certain models etc. no manual or schematic links here.
For the SB200/201 click here also here also here and this one is very nicely done. here
Great site for model HW-101 only. click here
Trouble shooting tips about 30 models click here
CW Filters for Heathkit radios click here
Improvements for the SB-220 Nov.-Dec., 1990 QST article). click here
Heathkit HW-100/101 and SB-100/101/101W/102 click here
This company will make replacement variable capacitors for heathkit line. They were the original manufacturer for heath http://www.orenelliottproducts.com/