Heathkit Test Equipment Model Number Scheme

In my last blog post you may have noticed the Heathkit model numbers for the various shortwave receivers. Three were in the AR series, four were GR models, a couple were SB, and the last two Heathkit made were designated with SW. We also had the GC-1 and GC-1A. There seems to be some pattern here but not a very consistent one.

While researching my book Classic Heathkit Electronic Test Equipment I spent some time looking into the commonly used model series for test equipment.

Over the years Heathkit used various product naming systems. Other than some early accessories, they followed a system that used one to three letters indicating a major product line, followed by a unique number. For example, the IM-18 denoted an instrument in the IM (meter) series. During the heyday they had a pretty consistent product naming scheme. The table below lists the major product series. Some units, particularly test equipment, could be bought either in kit form or assembled. Some of the product lines indicate factory assembled or "wired" versions. For products that were offered assembled only, they were sometimes branded as "Heath", particularly in the later days when they were out of the kit business and the units were part of an educational product. Often the wired and kit versions used similar model numbers, such as SM-1212 and IM-1212, but this was not always the case.

Series	Description
numbers	Adaptors and probes
AG	Audio Generators
AV	VTVMs
C	Condenser Checkers
ES	Power Supplies
ETI	Instruments from Educational Series
EU	Malmstadt-Enke Instruments
EUW	Malmstadt-Enke Instruments (wired)
G	Signal Generators
GD	Grid Dip Meters
IB	Impedance Bridges
IG	Signal Generators
IM	Meters
IN	Component Substitution Boxes
IO	Oscilloscopes
IP	Power Supplies
IR	Chart Recorders
IT	Miscellaneous Testers
O	Oscilloscopes
OM	Oscilloscopes
PK	Probes
PKW	Probes (wired)
PS	Power Supplies
S	Electronic Switches
SG	Signal Generators
SM	Factory Assembled Versions of IM Series
SO	Factory Assembled Versions of IO Series
SP	Factory Assembled Versions of IP Series
T	Signal Tracers
TC	Tube Checkers
TS	TV Sweep/Alignment Generators
TT	Tube Testers
V	VTVMs
VC	Oscilloscope Calibrators