A Field Guide to Heathkit

This volume is the reference shelf for the rest of the dive. It explains how to read a Heathkit model number, lists the landmark kits in order, shows how the catalogue changed over the years, sets out how to date a kit or a manual, corrects the most persistent myths with the evidence, and says where the manuals and catalogues can be found today. The earlier volumes tell the history. This one is for the reader holding an unidentified grey box at a hamfest and asking what it is, when it was made and where to find its book.

The figures in this volume come mainly from two sources. The first is the Nostalgic Kits Central model matrix, an enthusiast database of more than 1,400 Heathkit model numbers with first and last catalogue years (Nostalgic Kits Central). The second is Heath’s own catalogues and manuals as scanned on the Internet Archive and World Radio History. Where the database and a primary document disagree, the document is preferred and the disagreement is noted.

9.1 Reading a model number

9.1.1 The prefix system

A Heathkit model number is a letter prefix, a hyphen and a number: IM-11, SB-102, GR-2000. The prefix names the product line. No Heath document that decodes the letters has been found, so the meanings below are inferred from the products that carry each prefix in the model matrix. The pattern is consistent enough that the inference is safe: the first letter usually gives the market (I for instruments, H for ham radio, A for audio, G for general consumer products, E for education and scientific, M for marine, C for automotive), and the second letter the kind of device.

Table 1 — The prefix system

Prefix	Product line (inferred from the kits)	Models in matrix	Catalogue years	Examples
IM	Instrument, meter: VTVMs, VOMs, DMMs, counters	58	1951–1991	IM-11, IM-13, IM-25, IM-105
IO	Instrument, oscilloscope	29	1960–1989	IO-10, IO-102, IO-4510
IG	Instrument, generator: audio, RF, function	33	1962–1989	IG-18, IG-5280
IT	Instrument, tester: tubes, transistors, capacitors	27	1953–1985	IT-17, IT-3121
IP	Instrument, power supply	25	1961–1984	IP-32, IP-2717
IB	Instrument, bridge (later also counters)	14	1950–1977	IB-2
IN	Substitution boxes (resistor, capacitor)	12	1961–1991	IN-11, IN-17
IC	Calculators (and a few instruments)	11	1972–1989	IC-2108
ID	Digital and miscellaneous instruments, weather stations, automotive meters	29	1964–1990	ID-29, ID-4001, ID-5001
HW	Ham transceivers (the single-band and HF “HW” line)	36	1960–1985	HW-12, HW-16, HW-101, HW-8
SB	The SB (“single sideband”) amateur line: receivers, transmitters, transceivers, linears, station accessories	34	1959–1988	SB-300, SB-401, SB-102, SB-200
HR	Ham receivers	4	1961–1976	HR-10, HR-1680
HX	Ham transmitters	6	1961–1979	HX-10, HX-1681
HG	Ham generator (VFO)	2	1961–1967	HG-10, HG-10B
HA	Ham amplifiers	10	1961–1987	HA-10
HD	Ham devices: keyers, phone patches, code oscillators, dip meters	34	1957–1990	HD-1250, HD-1410
HM	Ham meters: wattmeters, SWR bridges	11	1961–1984	HM-2140
HN	Dummy loads	2	1961–1983	HN-31 “Cantenna”
HP	Ham power supplies	15	1960–1980	HP-23
DX	Early AM/CW transmitters	11	1955–1967	DX-35, DX-40, DX-100
AA	Audio amplifiers	49	1958–1989	AA-100, AA-1640
AR	Audio receivers (earlier: SWL receivers)	20	1949–1983	AR-15, AR-1500
AJ	Audio tuners	25	1961–1981	AJ-1510
AS	Audio speakers	24	1964–1983	AS-2
AD	Audio devices: turntables, tape, processors	41	1961–1991	AD-1305
GR	General consumer receivers: radios and televisions	63	1961–1984	GR-2000, GR-900
GD	General devices: home, hobby and radio-control products	73	1952–1992	GD-1 dip meter, GD-1183 freezer alarm
GC	Clocks	19	1960–1984	GC-1005, GC-1000
GW	CB radios	21	1960–1967	GW-10
H / WH	Computers and peripherals (WH = wired)	22	1977–	H8, H11, H19, H89, WH-89
ET / ETA / ETW	Educational trainers and robots	15+	1958–1990	ET-3400, ET-18 (HERO 1)
EE	Individual Learning course books	not in matrix	1970s–1999	EE-3101, EE-3104, EE-1800
EC / ES	Analog computers and components	12	1956–1971	EC-1, ES-400
EU / EUW / EV	Scientific instruments (the Malmstadt-Enke laboratory line)	30+	1963–1971	EU-20, EUW-17
MI / MR / MW	Marine instruments, receivers, radiotelephones	20+	1959–1981	MI-18, MR-1010
CI / CM / CO / CP	Automotive: indicators, meters, analysers, ignition	20+	1956–1989	CO-1015, CP-1060
SM / SO / SG / SP	Assembled “Heath/Schlumberger” instruments	50+	1971–1990	SM-2410, SP-2717A
O, V, G, C, T, A, W	Single-letter series of 1947–1958	~60	1947–1958	O-1, V-7A, G-1, A-7, W-5M

Counts and years are from the model matrix (Nostalgic Kits Central). The EE course numbers are from Heathkit/Zenith course books on the Internet Archive (EE-3101 DC Electronics; EE-3101-C, 1999; EE-1800 Robotics & Industrial Electronics).

Three facts behind the table deserve a note.

• The SB prefix is not ham-only. The SB line began as amateur radio but later included an SB-610 monitor scope and SB-series station accessories. The HW prefix covered transceivers almost exclusively (34 of its 36 entries).
• The S-prefix instruments are assembled versions. The matrix records the SP-2717 as the “assembled IP-2717” power supply. The SM, SO, SG and SP series of the 1970s and 1980s are the factory-built versions of IM, IO, IG and IP kits, sold under the Heath/Schlumberger instrument name (Nostalgic Kits Central). The “Heath/Schlumberger Electronic Instruments” catalogues of 1974 and 1978 on World Radio History are the matching sales literature (World Radio History).
• The early single letters were a different system. From 1947 to about 1958 Heath used one letter and a digit: O for oscilloscopes (O-1 to O-12), V for VTVMs (V-1 to V-7A), G for generators, C for condenser checkers, T for signal tracers, A for audio amplifiers, W for the Williamson-type power amplifiers. These were replaced by two-letter prefixes around 1959–1961.

9.1.2 Suffix letters

• A, B, C after the number mark revisions of the same model: V-7 then V-7A (1955, a thicker circuit board) (Brueschke and Mack, p. 147); HG-10 then HG-10B; SB-104 then SB-104A. A revised model normally had a revised manual, so the suffix on the manual must match the suffix on the panel.
• W in a prefix or before it marks a wired (factory-assembled) version: WH-89 for the assembled H-89, and EUW-, IGW-, ETW-, GCW- and ACW- in the matrix. Gilmore noted that Heath used “Wired” and “Assembled” interchangeably (Electronic Design, 30 November 2020).
• A appended to the prefix marks an accessory for that line, usually followed by the parent model number and a dash number: SBA-100-1 (a mounting bracket for the SB-100), HWA-7-1, IMA-18-1, IDA-5001-1, GRA- television accessories, AJA-1510-1. The restarted company still numbers its upgrades this way (IGA-18-1, AJA-1510-1, GCA-1006-5) (Heathkit shop).

9.1.3 Number length

Two- and three-digit numbers (IM-11, SB-102) belong to the 1950s through mid-1970s. Four-digit numbers (AJ-1510, ID-4001, IO-4510, SB-1000, HW-5400, GC-1000) mark the later 1970s and 1980s, when the catalogue had outgrown the short numbers. A four-digit number on a kit is therefore a good sign that it dates from after about 1974. That rule is inferred from the model matrix, not stated in any Heath document, so the manual’s print date should settle any doubt.

9.2 Landmark kits by year

The table gives the first catalogue year recorded in the model matrix unless another source is cited. The matrix is sometimes late by a year or more. It gives the ET-3400 trainer as 1981, although the trainer was on sale in the 1970s, so years should be read as “in the catalogue by”.

Table 2 — Landmark kits by year

Year	Kit	Why it matters
1947	O-1 oscilloscope	The first Heathkit, advertised in the July 1947 Radio News at $39.50 (Gilmore)
1947	V-1 VTVM	Start of the best-selling instrument line; the last Heath VTVM was sold in 1989 (Gilmore)
1949	AR-1 receiver	Early general-coverage receiver
1951	AT-1 transmitter	Heath’s first amateur transmitter (1951–1956)
1955	V-7 VTVM	First printed-circuit Heathkit; V-7A followed within the year (Brueschke and Mack)
1955	DX-100 transmitter	100 W AM/CW, 160–10 m
1956	ES-400 analog computer	Heath’s first analog computer system, $945 in 1956 (per the sibling ES-400 dive on this site)
1958	TX-1 Apache, RX-1 Mohawk	The large “tribal” station pair
1959	EC-1 analog computer	Educational analog computer, 1959–1971 (per the sibling EC-1 dive)
1961	HN-31 “Cantenna”	Dummy load in the catalogue until 1991; with the VTVM, the lifetime volume leader (Gilmore)
1961	AA-100 integrated amplifier	$84.95
1963	HW-12 “Singlebander”	$119.95 single-band SSB transceiver, start of the HW line
1963–1964	SB-300 receiver, SB-400 transmitter	The SB line begins
1964–1968	SB-200 linear amplifier	Probably the top ham kit by lifetime dollars (Gilmore); the matrix says 1964, Gilmore 1968
1965	SB-100 transceiver	$360; SB-101 (1967), SB-102 (1970)
1966	SB-301, SB-401	The revised receiver and transmitter pair (SB-301 kit $260)
1967	AR-15 receiver	The audio flagship Gilmore said put Heath “in the top tier”
1967	HW-16	CW novice transceiver
1970	HW-101	The long-running HF transceiver (1970–1983)
1972	GR-2000 colour television	Digital channel and time display on screen
1972	GC-1005 clock	Neon digital clock
1974	SB-104	All solid-state HF transceiver; SB-104A 1977
1975	AJ-1510	Digitally synthesised FM tuner
1976	HW-8	QRP transceiver
1977	H8, H9, H11	The computer line, first shown in the August/Fall 1977 catalogue (Gilmore)
1978	ID-4001 weather station	Digital weather station (to 1992)
1982	HERO 1 (ET-18) robot	Project begun 1979, released 1982 (per the sibling HERO 1 dive)
1982	SS-9000	Factory-assembled synthesised HF transceiver
1983	GC-1000 “Most Accurate Clock”	WWV-synchronised clock (to 1992)
1984	HERO Jr (RT-1)	Home robot, about $600 (per the sibling HERO Jr dive)
1987	HK-232	Multi-mode packet TNC
1990	H-5100 / HS-5100	”Builder-friendly” 80286/80386SX computer; proofbuild July 1990 (Internet Archive)
2015	GR-150 / GR-152 Explorer	First kit of the restarted company
2016	GC-1006 Most Reliable Clock	Restart-era flagship
2025	CubeSatSim Heathkit Edition	First product of the Kirkwall era

Years and prices without a separate link are from the model matrix (Nostalgic Kits Central).

9.3 The catalogues, year by year

Heath sold almost entirely by mail until the early 1960s and mainly by mail for long after, so the catalogue was the company’s shop window. Two kinds of evidence let its growth be measured: the page counts of surviving scans, and the kit counts printed on the covers.

Table 3 — The catalogues, year by year

Catalogue	Pages (scan images)	Cover or other claim	Where
February 1948 flyer	single sheet	”Feb. Flyer of Electronic Specials”: $19.50 signal generator kit, $4.95 surplus modulator	Internet Archive
1956	64	”World’s finest electronic equipment in kit form”; “a subsidiary of Daystrom, Incorporated”	Internet Archive
Fall & Winter 1961–62	106	”Plant location: St. Joseph, Michigan”; Daystrom subsidiary	Internet Archive
1963 (electronic kits)	55	$5 introductory certificate	Internet Archive
1966, 810/60	117	”over 250 electronic kits—world’s largest selection”	Internet Archive
1971, 810/72	96	”25th year”	Internet Archive
1972, 800/28	88	AR-1500 receiver on the cover	Internet Archive
August/Fall 1977	104 pages	Computers get 10 pages; test 21, audio 15, ham 11	Gilmore
Winter 1980, No. 848	PDF	”Heathkit Mail Order Catalog No. 848”	Internet Archive
Fall 1984	114	Savings-certificate cover	Internet Archive
Spring–Summer 1986	PDF	HERO 2000 on the cover	Internet Archive
Summer 1990, Volume 221	PDF	HS-5100 “builder-friendly” computer; “Half price on all remaining” audio units	Internet Archive

Scan-image counts include covers and the occasional blank, so they slightly overstate printed pages. Gilmore adds that mid-1970s catalogues featured “over 400 products in kit form” (Electronic Design).

9.3.1 How many catalogues survive for each year

World Radio History’s Heathkit page links about 120 distinct PDFs. Grouped by year they show the rhythm of Heath’s publishing: monthly flyers in 1948–1950 (eight survive from 1949 alone), fewer and larger catalogues through the 1950s and 1960s, then three to six a year in the late 1970s and early 1980s (spring, fall, Christmas, winter), falling to one or two a year by 1986–1991. The last general catalogue on the list is Winter 1991 (No. 223), and the last item of all is a 1993 education catalogue (No. 279) (World Radio History). No catalogues survive there for 1953, 1957, 1960 or 1989, which points to gaps in collecting rather than in publishing.

Table 4 — How many catalogues survive for each year

Period	Catalogues and flyers on World Radio History
1947–1949	13 (almost all monthly flyers)
1950–1959	20
1960–1969	22 (including Italian and French editions)
1970–1979	35 (including German, international and Schlumberger instrument editions)
1980–1989	27
1990–1993	4

The covers of the 1956, 1961–62, 1966, 1972 and 1980 catalogues appear in the chapters that cover those years.

9.4 How to date a Heathkit

9.4.1 The manual part number

Every Heath manual carries a part number in the 595- series, printed on the front cover (the parts list says only “Manual (See front cover for part number)”). The numbers were issued roughly in sequence, so the number itself dates the manual. A two-digit dash suffix gives the revision.

Table 5 — The manual part number

Manual	Part number	Date printed in manual
IM-10 service-bench VTVM	595-362	”Copyright 1960 9/9/60”
HN-31 “Cantenna”	595-527-03	Copyright 1962 (revision 03, a later printing with the Heath/Schlumberger Kit Builder’s Guide)
IM-25 solid-state VOM	595-1042-02	1967
IO-102 oscilloscope	595-1285-01 / -02	Copyright 1971
IM-105 VOM	595-1335	c. 1971–72
ET-3300B breadboard	595-2937-02	Copyright 1983
H-5100 computer	595-4696	Copyright 1990

Sources: the manuals on the Internet Archive (IM-10, HN-31, IM-25, IO-102, IM-105, ET-3300B, H-5100).

Two cautions apply. The copyright year is the year of first publication, not of the printing in hand: the HN-31 manual keeps its 1962 copyright line in a later revision whose Kit Builder’s Guide carries the Heath/Schlumberger logo. And the revision suffix matters: -01 and -02 printings of the IO-102 manual both exist.

9.4.2 Heath’s other part-number families

The replacement-parts list in any manual doubles as a key to Heath’s internal numbering. In the 1971 IO-102 list: 1- for 1/2-watt resistors (1-xx-1 for 1-watt), 3-xx-7 for 7-watt wirewound resistors, 23- and 25- for capacitors (25- for electrolytics), 56- and 57- for zener and silicon diodes, 417- for transistors, 344- for hook-up wire (priced by the foot), 331- for solder, 85- for circuit boards, 597- for inserts such as the Kit Builders Guide (597-308), and 595- for manuals (IO-102 manual). A loose Heath part with its number still on the envelope can usually be placed in its family from this list. The restarted company still sells parts in the 100-, 266- and 455- families (Heathkit shop).

9.4.3 Corporate identity lines

The owner’s name printed on a catalogue or manual brackets its date:

• “A subsidiary of Daystrom, Incorporated” appears on catalogues from the Daystrom years (1955–1962); the 1956 and 1961–62 catalogues carry it (1956; 1961–62).
• “Heath / Schlumberger” marks the 1962–1979 Schlumberger era. It appears on the Kit Builder’s Guide and on the 1971 catalogue (HN-31 manual; 1971 catalogue).
• Heath/Zenith branding and the rounded “Heathkit” wordmark belong to the Zenith years (1979–1989) and after (ET-3300B manual).
• ZIP code 49022 after “Benton Harbor, Michigan” dates a document to 1963 or later, when US ZIP codes began. The 1971 IO-102 manual’s warranty page gives “Benton Harbor, Michigan 49022” with a 616 area-code phone and a TWX number (IO-102 manual).
• A reference to Heathkit Electronic Centers (the retail stores) in the factory-repair section places a manual after the stores opened in the early 1960s (Gilmore).

9.4.4 The kit itself

The model matrix’s first and last catalogue years bracket a kit’s production run (Nostalgic Kits Central). Revision suffixes narrow it further. Construction gives a rough era. Point-to-point wiring on tube sockets and terminal strips belongs to the early kits; the printed circuit board arrived with the V-7 in 1955 and was “part of nearly every kit thereafter” (Gilmore). Transistors replaced tubes from the early 1960s, the solid-state SB-104 arrived in 1974, and pre-built subassemblies became common in the 1980s. Cabinet colour and panel styling also changed by era, but no documentary source setting out a dated sequence of Heath cabinet styles was found, so the catalogue covers in this volume are the safest visual reference.

9.5 Common myths corrected

9.5.1 “Heathkit went out of business in 1992”

The kit line ended; the company did not. Heath Company continued as Heathkit Educational Systems and a lighting and security business, which were sold separately in 1995 and 1998. The educational company ran until its bankruptcy in 2012, and the name has been in continuous commercial use since the 2013 restart. A Heath employee wrote at the time: “The Company never went out of business. It is true that they no longer make kits” (Kaeding, Heathkit Virtual Museum; DESA S-4/A). The After the Kits volume follows the chain.

9.5.2 “Heath’s first amateur transmitter was the A1”

The A-series of 1951–1958 (A-1, A-3, A-4, A-7 and others) were audio amplifiers. Heath’s first amateur transmitter was the AT-1, in the catalogue from 1951 to 1956 (Nostalgic Kits Central). The error comes from dropping the T.

9.5.3 “No new kits after 1986”

Heath was still developing and proof-building kits in 1990. The internal proofbuild report for the H-5100 computer has a return date of July 1990 (Internet Archive); the Summer 1990 catalogue put the HS-5100 “builder-friendly computer” on its cover (Internet Archive); and a Winter 1991 catalogue exists (World Radio History). What is true is that the range was shrinking fast. The 1990 cover also advertises half price “on all remaining” audio units.

9.5.4 “Surface-mount parts killed the kits”

Surface-mount assembly and cheap factory labour both mattered, but a Heath executive of the period calls them “far from being the only reasons”. Gilmore says “there were plans afoot to make use of surface-mount technology”. He adds other causes: the cost of writing manuals, which assembled-product makers did not bear; builders with less spare time as kits took over 100 hours; computers drawing away the “early innovators”; and the demands of being a division of large public companies (Electronic Design). Brueschke and Mack list eight causes, including the complexity of the manuals and the repeated sale of the company to owners with “little interest in the Heathkit operation other than computers” (Brueschke and Mack, p. 152).

9.5.5 “Kits were always cheaper than buying assembled”

For the first decades, yes; that was Heath’s premise, and Gilmore’s “80% rule” (80 percent of the functionality at 20 percent of the price) described many early kits. By the 1980s it had often reversed. Steve Jobs, in a 1995 quotation later featured on Heathkit’s own website, remembered that “you actually paid more money for them than if you just went and bought the finished product if it was available” (heathkit.com, archived January 2012).

9.5.6 “Zenith Data Systems owned Heathkit”

Zenith owned both. Inside the St. Joseph building, according to Kaeding, Heathkit, Veritechnology and ZDS “each had their own President which reported to ZEC in Chicago”, and “ZDS did not at any time own Heathkit” (Kaeding).

9.5.7 “The Heath Zenith lights company is Heathkit”

HeathCo LLC of Bowling Green, Kentucky, which sells Heath Zenith motion lights and doorbells, descends from Heath’s lighting division. That division was sold to DESA in February 1998 with the Heathkit Division explicitly excluded (DESA S-4/A; HeathCo). The two companies have been separate for almost thirty years.

9.5.8 “Kirkwall bought Heathkit in 2024” (or 2023, depending on the retelling)

Both dates appear, and both are partly right. Kirkwall announced the acquisition on 28 August 2023; its chief executive physically moved Heathkit to Fargo in March and October 2024 (Kirkwall on LinkedIn; Fargo INC!, 30 January 2025). The chief executive’s name is William (Will) Cromarty; spellings such as “Crommarty” are errors.

9.5.9 “The old Heathkit plant was demolished”

The building at 211 Hilltop Road, St. Joseph, stands. It is the 522,467-square-foot Hilltop Business Center, bought by Clark Logic in 2023 and let to businesses, a foundation and a therapy clinic (Moody on the Market, 22 July 2026).

9.5.10 “Heathkit manuals are out of copyright, so anyone may copy them”

The present owner says the opposite, stating that its publications are “copyrighted worldwide by law whether or not marked” and that “‘Fair use’ provides no safe harbor” (Heathkit legal notices). Some older manuals may never have had their US copyrights renewed, and at least one archive says it checked titles against Copyright Office records and withheld the ones still protected (Tubular Electronics). The honest position is that the status varies from manual to manual and has to be checked title by title. No blanket statement in either direction is safe.

9.5.11 “The O-1 cost $39.95”

Retellings disagree on the price of the first kit: $39.50 or $39.95. Gilmore, citing the July 1947 Radio News introduction, gives $39.50 (Electronic Design). The first volume of this dive examines the O-1 in detail.

9.6 Where manuals and catalogues survive today

9.6.1 From the owner

Heath Company, through its Data Professionals business, sells paper reprints only, “1st generation copies made directly from an original manual”, with about twenty-two pages of listings at typically $2 to $30, and states: “We currently do not offer .PDF or any other ‘electronic’ copies for sale” (Data Professionals manual store). This is the only source that claims the owner’s authority.

9.6.2 Free archives

Table 6 — Free archives

Archive	What it holds	Notes
Internet Archive, Heathkit manuals collection	706 manuals and schematics	Most uploaded in January 2024
Internet Archive, Digital Library of Amateur Radio & Communications	New high-resolution scans of individual manuals (IO-102, IM-105, IM-25, SB-200, HN-31, IM-10 and many more)	Page-by-page images; e.g. IO-102
Vintage Radio Info	719 files: schematics, partial and complete manuals	Rebuilt from the defunct circuitarchive.co.uk collection
Tubular Electronics	Heath manuals A–Z	Withholds about 30 titles it believes still in copyright
KO4BB	About 140 Heathkit files	General manuals archive
W5RKL	118+ amateur-radio Heathkit documents	Ham-focused
AudioCircuit	About 300 audio schematics and service documents	Audio only
BAMA	A dozen models	Removed its large Heathkit collection in 2008
SEBHC	H8, H89, H19, H/Z-100, HDOS, CP/M documentation	Computers only
bitsavers	H11, Z89, Z100 and other Zenith/Heath computer documents	Computers only
Heathkit of the Month	133 illustrated articles with schematics	Histories and restoration notes, not manuals

9.6.3 Catalogues

Table 7 — Catalogues

Archive	Coverage
World Radio History	About 120 catalogues and flyers, 1947–1993, including foreign editions
Internet Archive	Individual catalogues, 1948–1990 (see the table above)
VE5JL Heathkit Catalogs	About 40 catalogues, 1954–1989, in a web viewer
Classic Heathkit Computers	Computer pages of 1977–1985 catalogues, plus REMark, Sextant and SEBHC newsletters

9.6.4 For model data

The Nostalgic Kits Central model matrix is the most complete index of Heathkit model numbers online, with first and last catalogue years, prices and specifications. The Heathkit Virtual Museum presents kits by category from the catalogues.

9.7 Suggested reading

• Brueschke, Erich E., and Michael Mack. “The History of the Heath Companies and Heathkits: 1909 to 2019.” The AWA Review 32 (2019). The most complete single history, from E. B. Heath’s aircraft to the Explorer radio. PDF via Wayback
• Frenzel, Lou. “Heathkit: An Employee’s Look Back.” Electronic Design, 30 November 2020. An interview with Chas Gilmore on product development, the Manual Department, the computer decision and the decline. Link
• Kaeding, Randy. “A Heathkit Story (Past & Present).” An employee’s account of the company’s structure around 1991 and after. Heathkit Virtual Museum
• Penson, Chuck. Heathkit: A Guide to the Amateur Radio Products. Electric Radio Press, 1995 and later editions. The standard reference on Heath ham gear (cited in Wikipedia’s bibliography; not consulted for this volume).
• Post, Rich. “The Heathkit Legacy.” Monitoring Times, July 2013. Link
• Eckweiler, Bob. Heathkit of the Month (2008–). OCARC index
• Sextant (1982–1987) and the Heath Users’ Group’s REMark, for the computer years. Sextant issue 1 · Classic Heathkit Computers

Sources

• Nostalgic Kits Central, Heathkit alphabetic equipment matrix. Link
• Frenzel, Lou. “Heathkit: An Employee’s Look Back” (interview with Chas Gilmore). Electronic Design, 30 November 2020. Link
• Brueschke, Erich E., and Michael Mack. The AWA Review 32 (2019). PDF via Wayback
• Kaeding, Randy. “A Heathkit Story (Past & Present).” Heathkit Virtual Museum
• DESA International Inc., Form S-4/A, 1998. SEC EDGAR
• HeathCo LLC, About. Link
• World Radio History, Heathkit catalogues. Link
• Internet Archive catalogues: Feb 1948 · 1956 · 1961–62 · 1963 · 1966 · 1971 · 1972 · 1980 · 1984 · 1986 · 1990
• Internet Archive manuals: IM-10 · HN-31 · IM-25 · IO-102 · IM-105 · ET-3300B · H-5100 and proofbuild report
• Internet Archive course books: EE-3101 DC Electronics · EE-3101-C (1999) · EE-1800
• heathkit.com, archived 5 January 2012. Wayback Machine
• Heathkit legal notices. Link
• Heathkit shop. Link
• Data Professionals manual store. Link
• Kirkwall acquisition announcement, 28 August 2023. LinkedIn
• Fargo INC! “A Year as a Startup: The Journey of Kirkwall,” 30 January 2025. Link
• Moody on the Market, 22 July 2026. Link
• Tubular Electronics, Heathkit manuals. Link
• Archives listed in the manuals tables above: Vintage Radio Info · KO4BB · W5RKL · AudioCircuit · BAMA · SEBHC · bitsavers · VE5JL · Classic Heathkit Computers
• Wikipedia, “Heathkit” (lead only). Link