WA5VLZ, Neil, shows the tube line-ups and gives a description of each model.
http://www.io.com/~nielw/hro_modl.htm
Construction article for builing this receiver accessory to filter out crud. Schematic diagram and parts list are included.
http://www.mines.uidaho.edu/~glowbugs/soj.htm
This is a tutorial to decibels and other radio terms you might encounter in various radio applications.
http://www.x.net.au/tutorial.html
How to set up a simple, yet effective, ground system that can be installed in a short period of time with a minimum number of tools.
http://www.hard-core-dx.com/nordicdx/antenna/ground/ground3.html
How do radio receivers manage to communicate over huge distances? An explanation of the fundamental mechanism.
http://www.4p8.com/eric.brasseur/receiv.html
from FCC
http://wireless.fcc.gov/services/personal/family/
WA5VLZ provides information about this classic receiver with description, and pictures.
http://www.io.com/~nielw/nat_list/hro600.htm
Information, pictures, and notes. By Nolan Lee.
http://www.acadiacom.net/nlee/r-1051_index.html