[Heathkit] Heathkit shaft pulleys, etc.

[Ted Bruce]

My restoration of a couple of Tempo 2020 hybrid rigs required replacement of the 
sprockets and ladder chain that these rigs use. Since I can't seem to stop 
slippage of rubber belts on my HW-101, and I've found the string system way too 
fiddly for my old fingers, I'm going to switch over to the sprocket and chain 
system. The company I bought the 6mm shaft components for the Tempo 2020 is 
SDP-SI (www.sdp-si.com). They have 1/4" shaft size components as well. What is 
needed is to stick to similar-sized sprockets to the the existing pulleys to get 
similar "tuning" rates. The pitch of the sprocket gears must be matched to 
ladder chains of the same pitch for compatibility. The online catalog makes this 
easy to figure out. Sprockets are priced individually, and the matching ladder 
chain is sold in 1 meter lengths. The sprockets I used in the '2020 are acetyl 
plastic (Delrin) to replace the old cracked nylon ones.

If you want to see what is entailed for sprocket replacement, check out the 
Tempo 2020 repair procedures on my web site at www.kx4om.com. The changeover for 
Heathkit rigs will not be nearly as involved as in a Tempo 2020. It will require 
removal of the soldered-on pulleys from the Heatkit shafts. The '2020 has 
several sprockets in each of 2 drive trains (bandswitch and preselector 
assemblies). There is some brief overview info on the main page, and more 
detailed info including downloadable PDF files of the procedures here:
 
http://www.kx4om.com/TechSolutions/Tempo2020_repairs/2020.html

73,
Ted, KX4OM