Avionics Reference — ARINC 410 / 566A Series, Part 3

The Complete Collins 618M Lineage

From ARINC 410 Origins (618M-1) to ARINC 566A/429 (618M-5) · The 313N Series Map · Gables Panel Pairings Confirmed

CORRECTIONS & ENRICHMENT FROM JAN SP5XZG  ·  COMPILED: VK6ADA, APRIL 2026

1. Correction — The 618M Family Did Not End in the 1970s

Jan’s most important correction is that the Collins 618M series continued in production well into the 1990s. The first two articles treated the 618M as a 1960s–70s ARINC 410 product line and left readers with the impression that it had been entirely replaced by the VHF-20 series. This is incorrect, and the full lineage is more technically interesting than that.

The 618M series split into two distinct branches at some point in the 1970s–80s. The early models (618M-1 through 618M-3A) were the ARINC 410 parallel-tuned airline workhorses described previously. Collins then developed the 618M-4 and 618M-5 as updated heavy-transport VHF COM transceivers supporting 8.33 kHz channel spacing — and these required a fundamentally different control interface. Jan identifies this correctly: “I have no idea how to select the narrow band channels on a mechanical control unit, which would be also intelligible to the pilot.” This is a sharp observation. The answer is that you cannot — which is exactly why the later 618M variants moved away from ARINC 410.

Model	Era / P/N Prefix	Freq Range	Channel Spacing	Control Interface	Notes
618M-1 / 1A	Early 1960s / 522-2755 (618M-1) · 522-2754 (618M-1A)	118.0–135.95 MHz	50 kHz (360 ch)	ARINC 410 (2-of-5)	313N-1 and later 313N series. TSO C37b/C38b.
618M-2 / 2B	Mid 1960s / 522-4088	118.0–135.975 MHz	25 kHz (720 ch)	ARINC 410 (2-of-5)	Explicitly documented: “any 2-out-of-5 ARINC format control.”
618M-3 / 3A	Late 1960s / 622-1181	118.0–135.975 (3) / 116–151.975 (3A)	25 kHz (720 ch)	ARINC 410 (2-of-5)	313N-5 / 313N-5A. 3A adds 2m HAM band coverage to 151.975 MHz. Extended range still mechanical tuning.
618M-4 / 4A	1980s / 822-0732	118.0–136.975 MHz	25 kHz and 8.33 kHz	ARINC 566A / ARINC 429	Break from ARINC 410. 822-prefix P/N confirms digital-era design. 8.33 kHz requires serial bus control — mechanical heads cannot address the channel grid.
618M-5 / 5A	1990s / 822-1045 / 822-1046	118.0–136.975 MHz	25 kHz and 8.33 kHz	ARINC 566A + ARINC 429	Boeing 737-600/700/800/900 (Next Generation). Paired with Gables G7406-04. Anatel certified 2006. Jan SP5XZG’s identified pairing confirmed.

1.1 What Is ARINC 566A — and Where Does It Fit?

Jan’s email lists the G7406-04’s compliance as including ARINC 566A alongside ARINC 429, 716, 720, 724B, and 750. ARINC 566A is the Mark 3 VHF Communications Transceiver characteristic — the updated successor to ARINC 546, first drafted Spring 1972 (AEEC General Session, Montreal); last revised 30 January 1998. It bridges the transition between the analogue 500-series world and the digital 700-series world. It sits at a conceptually important crossover point:

• ARINC 566A retains 2-of-5 wire frequency selection as one permitted control interface for backwards compatibility with aircraft wired for ARINC 410 control heads.

• ARINC 566A also permits ARINC 429 digital bus tuning as an alternative, enabling connection to FMS and digital management systems.

• The Gables G7406 series lists both ARINC 566A and ARINC 429 — this is precisely why Jan notes that “these control units support both ARINC 429 and/or 2×5 radio tuning.” This is not a contradiction; it is ARINC 566A working as designed.

This dual-interface architecture also explains how the 618M-5 could be fitted on Boeing 737NG aircraft operated by airlines with different avionics configurations: FMS-equipped aircraft use ARINC 429 tuning from the FMS, while the panel provides a local backup via the 2-of-5 lines. On aircraft without FMS or with older flight management, the 2-of-5 mechanical selector remains the primary tuning interface.

The digital era was firmly established with ARINC 429, adopted by the Airlines Electronic Engineering Committee in July 1977. ARINC 429 is a simplex (one-way), twisted shielded pair data bus that operates at either 12.5 kbps or 100 kbps, allowing a single transmitter to drive up to 20 receivers [3]. This serial bus replaced the bulky parallel wiring of ARINC 410 and became the dominant data bus in commercial aviation. Collins also developed the proprietary Commercial Standard Digital Bus (CSDB) — used in the Pro Line II CTL-22 and CTL-22C control heads — before the industry fully standardised on ARINC 429 [4].

2. The Collins 313N Series — A Definitive Compatibility Map

Jan’s second key contribution is a careful breakdown of the 313N sub-series, including points that go beyond what any single online source documents. Combining his observations with what can be confirmed from parts databases and the Collins VHF-20 documentation page, the following picture emerges:

Head	Physical Form	Function	Primary Radio	8.33 kHz?
313N-1	Panel-mount, non-Dzus enclosure	COM only	618F-1C, 618F-1D. Also reportedly compatible with 618M-1 per Jan SP5XZG. Not Dzus-mounted — a common misattribution.	✗ No
313N-2 / 313N-3	Both 313N-2 and 313N-3 used Dzus quarter-turn fastener panel enclosures. Both are dual COM/NAV heads in the same functional family. Confirmed by Jan SP5XZG from primary documentation.[6]	COM + NAV (dual function)	618M series and VHF-20 series; paired with navigation receivers (VIR-30/31/32 etc.)	✗ No
313N-2D	Dual COM/NAV/DME; Dzus panel	VHF-20A/B series primary control. Freq. selection: “ARINC 410, digital binary code (2×5 wire).” Also controls DME.	✗ No
313N-4 / 313N-4D	Small square face, non-Dzus; several sub-variants	COM-only variants and NAV/COM variants	618M series and VHF-20 series. 313N-4D: isolation diodes for tandem dual-head per ARINC 410. ILS 40-channel variants available.	✗ No
313N-5 / 313N-5A	Square face; -5XX series with internal diodes	COM-only and COM+NAV variants. Extended freq range on some variants.	618M-2B through 618M-3A; VHF-20 series. 313N-5 has extended freq range (116–151.975 MHz); 313N-5A does not (stops at 135.975 MHz). Weight: 1.1 lbs. Part numbers: 522-2599-xxx series.	✗ No
CTL-20	Pro Line I style; 720 or 760 channel selection	COM only — controls one VHF-20A	VHF-20A/B/C primary control. ARINC 410 2×5 wire output confirmed.	✗ No[3]
CTL-21	Pro Line I style — updated CTL-20	COM only — parallel tuning	VHF-21A/B series	✗ No
CTL-22 / 22C	Digital LCD display; encoder knobs	COM — serial digital bus output	VHF-21C/D and VHF-22 series. CSDB serial bus (EIA RS-422A physical layer, 50 kbit/s max). First Collins control head to support 8.33 kHz. Six frequency memories. Active and preset frequency display. Part numbers: 822-1120-xxx series.	✔ Yes

3. The 618M Variants Covering 152 MHz — And Amateur Radio

Jan makes a particularly interesting observation: some 618M variants covered up to 152 MHz, which overlaps with the 2-metre amateur radio band (144–148 MHz). These are the 618M-3A (116.0–151.975 MHz) and later the 618M-4A and 618M-5 with extended range.^[4] The extended range was not primarily for amateur use — it served special operations frequencies above the standard aeronautical COM band that certain government and military operator types require (136–152 MHz is used by various maritime, meteorological, and special operations services).

For the 618M-3A with its mechanical ARINC 410 control, the 313N-5 (with extended range capability) is the appropriate control head. The 313N-5A does not have extended frequency range — a detail that matters when sourcing control heads for 618M-3A installations. Collins’ part number notes confirm: the 313N-5 has extended frequency range tuning capability; the 313N-5A does not.^[5]

The amateur radio relevance is real for those who know: a 618M-3A connected to a 313N-5 control head and fed a suitable antenna is, technically, an AM transceiver capable of operating on 144–148 MHz. Whether this is legal or advisable is a separate matter — but the hardware capability exists, and Jan SP5XZG’s observation on this point is accurate.

4. Gables Control Panels Paired with Collins VHF AM Sets — A Consolidated Reference

Jan specifically requests a mapping of Gables control panels to Collins VHF AM airborne sets supporting ARINC 410 2-of-5 tuning. Combining confirmed pairings from Gables datasheets, the Collins VHF-20 documentation page, and parts database cross-references:

Gables Panel Family	Era	Control Interface	Compatible Collins Sets	Notes
G-1756A	1960s	ARINC 410 (2-of-5)	618M-1 / 618M-2 era	NAV + VHF COM control. Confirmed in surplus documentation as “Nav-VHF Communication Control Panel.”
G-2140 ⚠	1960s (est.)	ARINC 410 (inferred)	618M series (est.)	⚠ Unverified. Known only from a single surplus parts listing as “Gables Engineering VHF NAV Control Panel.” Jan SP5XZG reports this model cannot be found on the web; no photographs, datasheet, or rear connector information has been located. Model number sequence places it in the 1960s. Treat as unconfirmed pending primary documentation.
G-2346 ⚠	1960s–70s (est.)	ARINC 410 (inferred)	618M-2 / 618M-3 era (est.)	⚠ Unverified. Known only from a surplus listing as “AIRCRAFT COMM/NAV/DME VHF CONTROL PANEL.” Jan SP5XZG reports this model cannot be located on the web; no photographs, datasheet, or rear connector information has been found. ARINC 410 compliance is inferred from era and market — not confirmed from documentation. Treat as unconfirmed pending primary source.
G-2349A (dual)	1960s–70s	ARINC 410 (2-of-5) with isolation diodes	618M-2 / 618M-3 era (dual installation)	Identified by Jan SP5XZG via reiding.com teardown. Dual control head for two transceivers; contains isolation diodes for tandem operation per ARINC 410.
G-4142 (multi)	1970s	ARINC 410 (2-of-5)	618M-3 / VHF-20 era	“Multi VHF Comm/Nav Control Panel” — confirmed airline equipment (DFW Air Parts listing). Multi-radio panel for triple-crew or multi-radio aircraft.
G-4434A	1970s–80s	ARINC 410 (2-of-5)	VHF-20 / 618M-3 era	“VHF Comm Control Panel” — confirmed surplus listing. Model number sequence consistent with late 1970s production.
G-4483B (dual)	1970s–80s	ARINC 410 (2-of-5)	VHF-20 / VHF-21A era	“Dual VHF Comm Control Panel” — confirmed surplus listing. Dual-head panel with isolation diodes for tandem use.
G7406-04	2003–present	ARINC 566A (2-of-5) + ARINC 429	Collins 618M-5 on Boeing 737-600/700/800/900	Jan SP5XZG’s confirmed pairing. 8.33 kHz capable. Dual ARINC 429 + 2-of-5 output. TSO-C37d/C38d. Full datasheet publicly available from Gables.
G7400 series	1990s–present	ARINC 429 + optional 2-of-5	Boeing 757/767; ARINC 716 transceivers (post-618M)	Primary interface is ARINC 429. Some variants also output 2-of-5 for backwards compatibility. Standard on B757/B767.

The Boeing 737 Next Generation (737-600/700/800/900) entered service in 1997, featuring a modern glass cockpit and digital avionics [5]. The G7406-04 panel was designed specifically for this era, interfacing with the digitally-controlled 618M-5 transceivers via ARINC 429.

5. The Corrected Complete Picture — Interface Evolution Across the 618M Lineage

Bringing together the three articles, Jan’s corrections, and the confirmed datasheets, the following evolution of the Collins 618M control interface is now firmly established:

  1962–75  618M-1, 618M-2/2B, 618M-3/3A
           ────────────────────────────────────────────────────────
           Interface: ARINC 410 (2-of-5 parallel wire)
           Control:   313N-1 through 313N-5A, Gables G-1756A/
                      G-2140⚠/G-2346⚠/G-2349A/G-4142 and equivalents
                      (⚠ = unverified — cannot be located on web)
           8.33 kHz:  ✗ Not possible on mechanical parallel heads
           Max freq:  135.975 MHz (standard) / 151.975 MHz (3A)

  ─────── TRANSITION ─────────────────────────────────────────────

  ~1980s   618M-4 / 618M-4A
           ────────────────────────────────────────────────────────
           Interface: ARINC 566A (retains 2-of-5 but adds digital)
                      and/or ARINC 429 serial bus
           Control:   Early G7400-series / G7406-series Gables panels
                      with LCD displays and digital encoders
           8.33 kHz:  ✔ Capable (requires digital control head)

  ─────── DIGITAL ERA ────────────────────────────────────────────

  ~1990s   618M-5 / 618M-5A   (Anatel cert 2006; active into 2000s)
           ────────────────────────────────────────────────────────
           Interface: ARINC 566A + ARINC 429
           Control:   Gables G7406-04 (confirmed; B737-600/700/800/900)
                      and G7400-series equivalents
           8.33 kHz:  ✔ Capable
           Note:      Part prefix 822-xxxx marks digital-era design

The Collins 618M designation thus spans an extraordinarily long production arc — from tube-era analogue equipment in 1962 through to a digitally controlled, 8.33 kHz-capable transceiver still being certified and overhauled into the 2000s. The model number continuity is a testament to Collins’ incremental approach to product development and to Boeing’s preference for form-fit-function replacements that minimised airframe modification costs.

6. Resources Referenced in This Article

Gables Engineering Datasheets

• Gables G7406-04 VHF COMM Control Panel Datasheet — confirms ARINC 566A + ARINC 429, B737-600/700/800/900, 8.33 kHz

• Gables VHF Comm Tuning — G7400 / G7406 / G7412 Product Page

• Gables G7612 NAV/GLS Panel Datasheet — lists ARINC 410 among compliance standards

Collins Control Head Documentation

• Collins 313N-5 — Southeast Aerospace — confirms 8.33 kHz incapability of all parallel heads; confirms -5XX diode variants

• Collins 313N-5A — Southeast Aerospace — standard 313N-5A without extended range

• Collins CTL-20 — Southeast Aerospace — 720/760 channel, ARINC 410, not 8.33 kHz capable

• Collins VHF-20 Documentation Page — complete 313N-2D and CTL-20 specifications with ARINC 410 confirmation

Collins 618M-5 Certification

• Rockwell Collins 618M-5 / 618M-5A Manual (ANATEL Brazil cert 2006) — confirms late production era and regulatory history

7. References

Footnotes

Avionics Reference Series, Part 3 — vk6ada.com.au

This article responds to further observations from Jan SP5XZG, who corrected the earlier articles’ treatment of the 618M as a 1970s-era product and contributed the Gables G7406-04 identification. Jan’s privacy preference regarding his surname is respected throughout this series — he is Jan SP5XZG.

HTML production: Mike Peace VK6ADA / r-390a.net Administrator. Information is provided for historical and technical reference; verify against primary manufacturer documentation before use for airworthiness purposes.

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