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The XCB-32: Building the Rarest S-Line Transmitter A reversible Extended Crystal Board kit that converts a Collins 32S-1 into a genuine-specification 32S-2 The Transmitter Art Collins Un-Named Ask a room full of Collins collectors to name every S-Line transmitter and most will get the 32S-1 and the 32S-3/3A without hesitation. The 32S-2 is the one… Read more: The XCB-32: Building the Rarest S-Line Transmitter

Fox-Tango Era • Yaesu Linear Amplifiers Yaesu FL-2100 / FL-2100B / FL-2100ZTuned Input Circuit: SWR Expectations & the Mica Capacitor Problem What input SWR should a healthy 572B grounded-grid amplifier show — and which of the two input capacitor styles is the one that fails? Reader Question — Dave, AI6VX (via the ham-amplifiers group) 1.… Read more: Yaesu FL-2100 / FL-2100B / FL-2100Z Tuned Input Circuit: SWR Expectations & the Mica Capacitor Problem

Boatanchor Legends · Tribute No. 50 Living Legend · Homebrew Master Dick Benson W1QG The engineer who retired, bought a $34 FPGA board, and built the Collins S-Line all over again — in silicon, in Simulink, and in salvaged HP instrument cases. Callsign W1QG — Richard A. Benson Home QTH Saratoga, California Licensed More than… Read more: Dick Benson – W1QG

Fox-Tango Legends — No. 007 Teruhiko Hayashi JA2SVZ The Man Who Kept the Counters Counting Every Fox-Tango Legend so far has kept the hybrid era alive with knowledge — survival guides, restorations, stewardship of the club itself. Teruhiko Hayashi, JA2SVZ, kept it alive with a part. Not a part Yaesu ever made, and not one… Read more: Teruhiko Hayashi, JA2SVZ

Collins S-Line Restoration Series Waking a Sleeping Collins Restoring a 75S-3B Receiver After 50 Years in Storage Mike Peace VK6ADA  ·  r-390a.net Administrator  ·  vk6ada.com.au A Collins 75S-3B that has slept in a shed, attic, or estate garage since the mid-1970s is one of the most rewarding restorations in all of vintage amateur radio —… Read more: Waking a Sleeping Collins: Restoring a 75S-3B After 50 Years in Storage

Reader Question · Fox-Tango Era Keying the Ameritron MLA-2500 with the Yaesu FR‑101/FL‑101 Twins Do the twins need a keying interface to drive a vintage tube amplifier? Short answer: no — and here is why. The Question “Do I need a keying circuit to use my Yaesu FR‑101 and FL‑101 twins with an Ameritron MLA‑2500… Read more: Do the FL-101/FR-101 Twins Need a Keying Interface for the Ameritron MLA-2500?

Grinding Your Own FT-243 — The 2026 Edition | VK6ADA

Boatanchor Legends · Tribute No. 48 Active · CCA Technical Editor Don Jackson, W5QN The Measurement Engineer of the S‑Line — the man who put real numbers behind the Collins legend, one careful analysis at a time ✍ Mike Peace VK6ADA / r-390a.net Administrator 📅 July 2026 ⚙ W5QN • Garland, Texas • Collins S-Line… Read more: Don Jackson, W5QN

Thirteen current SDR receivers and transceivers, compared for one thing that matters most to those of us who still copy Morse by ear and chase weak SSB DX: HF CW and SSB receive performance. The grid rates each unit, identifies which ones can put your antenna on the web for visitors, lists supported software, published… Read more: 2026 – Thirteen current SDR Receivers and Transceivers

Boatanchor Bench Notes · Sweep-Tube Hybrids Tempo One / Yaesu FT‑200: Chasing Down “No RF Output” A systematic bench walk-through for the hybrid FT-200 family (Henry Tempo One, Yaesu FT-200, Sommerkamp FT-250) — how to read the symptoms, isolate the fault, and repair it in the right order. This started as a bench question from… Read more: Tempo One / Yaesu FT‑200: Chasing Down “No RF Output”

Reader Question · Fox Tango International Why Does My FT-2000D Only Make 100 Watts? Diagnosing the half-power Yaesu FT-2000D — the 50 V PA rail, the SD2931 finals, ALC drift, and the misidentification trap. “I have a Yaesu FT-2000D that is supposed to put out 200 watts, but on every band it only makes about 100 watts into my… Read more: Why Does My FT-2000D Only Make 100 Watts?

A complete electrical & mechanical rebuild reference Hammarlund Restoration Series Hammarlund SP-600 JX-1 A complete electrical & mechanical rebuild reference Signal Corps R-274A/FRR  ·  Hammarlund Model 31406-1  ·  by Mike Peace VK6ADA / r-390a.net Administrator The Hammarlund SP-600 is one of the great commercial-military communications receivers of the tube era — a 20-tube, double-preselection, dual-conversion… Read more: Hammarlund SP-600 JX-1

Reader Question · from Rich, WA6KNW Driving a Collins KWM-2A or 75S-3B with an Electronic Specialty Products DDS VFO Q: “Does anyone have the manual for hooking up the Electronic Specialty Products DDS VFO (the N3ZI DDS-based unit) to a Collins radio — KWM-2A or 75S-3B?” — Rich, WA6KNW Good question, Rich — and a… Read more: Driving a Collins KWM-2A or 75S-3B with an Electronic Specialty Products DDS VFO

KWM-2A Clinic: When the Preselector Peak and Grid Drive Peak Don’t Agree A good question landed on the reflector recently from Lenny, WB6QAZ, who is bringing a round-emblem KWM-2A back to life. The radio is working well on both receive and transmit, but two things had him puzzled — and they’re both things nearly every… Read more: KWM-2A Clinic: When the Preselector Peak and Grid Drive Peak Don’t Agree

Yaesu FT-101E — Parts Substitution & Sourcing Reference Common failure points, modern equivalents and procurement notes for the FT-101E hybrid transceiver (12BY7A driver + 2×6JS6C finals; otherwise solid-state, dual conversion: 5 MHz 1st IF, 9 MHz VFO, 3.18 MHz 2nd IF). 20 Tracked Parts 7 Critical / Safety Items 14 Part Categories 12 Procurement Sources Parts Substitution Table Designators follow… Read more: Yaesu FT-101E — Parts Substitution & Sourcing Reference

VK6ADA Technical Reference  ·  Boatanchor Files The Collins R‑389, R‑390 & R‑390A Development, deployment, and a practical operator’s guide to the finest HF receivers of the vacuum-tube era — written for amateur radio operators and shortwave listeners, fact-checked against the primary engineering record. For seventy years the Collins R‑390A has worn the unofficial title of… Read more: The Collins R-389, R-390 and R-390A

Boatanchor Legends — A Tribute Series Carol Maher, W4CLM The keeper of the Fox Tango flame — who took a dormant newsletter club and built it into the definitive online home for Yaesu owners the world over. Some legends of the boatanchor world are remembered for a single rig they perfected, a circuit they pioneered,… Read more: Carol Maher – W4CLM

Boatanchor Legends — A Tribute Series Milton Lowens, WA2AOQ · N4ML The retired engineer who answered one radio’s design flaw by founding the most influential users group in amateur radio history — and proved that one man, one typewriter, and one good question can change an entire product line. Every great institution begins with a… Read more: Milton Lowens, WA2AOQ · N4ML

Boatanchor Legends · Tribute No. 47 Silent Key Glen E. Zook, K9STH First Article at Seventeen, and Six Decades Without Stopping Silent Key 22 July 2020, Richardson, Texas First Licensed as a teenager, K9 district (Indiana) Business Z-Communications Company Website k9sth.net (preserved) Glen Zook wrote his first article for 73 Magazine in 1961, at the… Read more: Glen Zook – K9STH

Boatanchor Legends · Tribute No. 46 Silent Key Dennis L. Brothers, WAØCBK From the Cedar Rapids Factory Floor to America’s Only Certified Collins Repair Center Born 9 February 1943, Kimball, Nebraska Silent Key 16 November 2024, age 81 Business Western Nebraska Electronics, Potter, NE Career ~50 years in electronics There is only one person in… Read more: Dennis L. Brothers, WAØCBK

Boatanchor Legends · Tribute No. 45 President · Collins Collectors Association Bill Carns, N7OTQ / KØCXX Art Collins’ Callsign Trustee, Editor of the Signal, Keeper of the Wimberley Shack Education BSEE 1964, MS Plasma Physics 1965, U. of Illinois First CCA Net Check-in 30 December 1990 CCA Founding Member AC94-0009 Home QTH Wimberley, Texas If… Read more: Bill Carns, N7OTQ / K0CXX

Boatanchor Legends · Tribute No. 44 Co-Founder · Collins Collectors Association Jay Roman, KBØATQ The Third Founder, and the Voice that Put the CCA Into Print First CCA Net Check-in 30 December 1990 CCM Founding Publisher June 1991 Original Board of Advisors August 1992 An on-air community can run for years and leave behind almost… Read more: Jay Roman, KBØATQ

Boatanchor Legends · Tribute No. 43 Silent Key Bud Whitney, K7RMT “K7 Rocky Mountain Time” — The Bench That Kept the Collins Fleet Alive Born 24 October 1919 Silent Key circa 2010–2012 Callsign Meaning K7 Rocky Mountain Time Workshop Wimberley, Texas By the time Bill Wheeler keyed the first Collins User Net on 14.263 MHz… Read more: Bud Whitney, K7RMT

Boatanchor Legends · Tribute No. 42 Active · Collins Engineer Rod Blocksome, KØDAS Collins Engineer, Historian, and the Man Who Brought a KWM-3 to Dayton First Licensed 1960 as KNØDAS Education BSEE 1968, MSEE 1973, Kansas State Career 42 years, Collins Radio / Rockwell Collins Home QTH Robins, Iowa Prior DX Calls VK2IHY, T30CXX, T32DAS… Read more: Rod Blocksome, KØDAS

Boatanchor Legends · Tribute No. 41 Silent Key Warren B. Bruene, W5OLY The Quiet Engineer Who Made Single Sideband Practical Born 1916, Iowa Silent Key 28 September 2013 Earlier Call WØTTK Home QTH Richardson, Texas If you have ever spoken into a Collins KWS-1, listened on a 75A-4, run a 30L-1 or 30S-1 amplifier, watched… Read more: Warren B. Bruene, W5OLY

Boatanchor Legends · Tribute No. 40 Silent Key Bill Wheeler, KØDEW The Quiet Founder of the Collins Collectors Association Born 18 July 1939 Silent Key 17 April 2020 First Licensed 1956 as KNØDEW Home QTH Lebanon, Missouri On a Sunday afternoon in February 1989, a Missouri ham with a fondness for Collins gear keyed up… Read more: Bill Wheeler K0DEW

ARRL Year of the Club · 2026 Club QSO Party The operating event designed FOR clubs, BY clubs The ARRL has officially declared 2026 the Year of the Club, and a brand-new on-the-air event has been launched specifically to energise members and put clubs front and centre. Other than Field Day, there are very few… Read more: Club QSO Party – 2026

Collins KWM-2 / KWM-2A Field Service Some KWM-2 / 2A Tricks A re-issue and enrichment of the January 2016 CCAE field-service article by Georges Ricaud, F6CER (CCAE #098), with primary-source cross-references for the Collins Collector community. Front panel of the Collins KWM-2A — photograph from the original CCAE article by Georges F6CER. Most of the KWM‑2 transceivers that turn up… Read more: Some KWM-2 / 2A Tricks by Georges Ricaud – F6CER

GPS-disciplined crystal channels for the Hammarlund SP-600-JX Bringing parts-per-billion frequency stability to a 1950s spy-radio classic using a $18 programmable crystal module and a GPS receiver The Hammarlund SP-600-JX is one of the great communications receivers of the vacuum-tube era — a precision general-coverage set built to military specifications, covering 540 kHz to 54 MHz, with a… Read more: GPS-disciplined crystal channels for the Hammarlund SP-600-JX

Capacitor Selection for Vintage Receiver, Transmitter, and Transceiver Restoration A practical reference for choosing replacement capacitors in premium HF tube equipment — from receivers like the R-390A and SP-600, through transmitters like the 32S-1 and Apache TX-1, to transceivers like the KWM-2A and Heathkit SB-101, plus linear amplifiers and specialty equipment. If resistors are the… Read more: Capacitor Selection for Vintage Receiver, Transmitter, and Transceiver Restoration

Low-Noise Resistor Selection for Vintage Receiver, Transmitter, and Transceiver Restoration A practical reference for choosing replacement resistors in premium HF tube equipment — from receivers like the R-390A and SP-600, through transmitters like the 32S-1 and Apache TX-1, to transceivers like the KWM-2A and Heathkit SB-101, plus linear amplifiers and specialty equipment. When restoring 60-to-70-year-old… Read more: Low-Noise Resistor Selection for Vintage Radio Restoration

The Boatanchor SDR Integration Series: Index and IF Buffer Amplifier Reference A consolidated index to the five SDR integration articles, plus a shared technical appendix on the buffered IF tap that most of them depend on. Over five companion articles, the Boatanchor SDR Integration Series has worked through what it takes to pair modern software-defined… Read more: The Boatanchor SDR Integration Series: Index and IF Buffer Amplifier Reference

Choosing an SDR for the Collins KWM-2A Transceiver The fifth in the Boatanchor SDR series — and the receiver Collins already built with external-receiver integration in mind. Companion articles: R-390A, Hammarlund SP-600, Collins 51S-1, and Collins S-Line 75S-1 / 32S-1 Station. Read the S-Line article for the four-SDR-roles framework (panadapter, TX monitor, off-air monitor, digital… Read more: Choosing an SDR for the Collins KWM-2A Transceiver

Choosing an SDR for the Collins S-Line Station: 75S-1 Receiver and 32S-1 Transmitter The fourth in the Boatanchor SDR series — and the first to cover a complete transmitting station rather than a single receiver. Companion articles: R-390A, Hammarlund SP-600, and Collins 51S-1 all concerned receive-only integration. The S-Line is different: pairing a 75S-1 with… Read more: Choosing an SDR for the Collins S-Line Station: 75S-1 Receiver and 32S-1 Transmitter

Choosing an SDR Front-End for the Collins 51S-1: Factory Outputs, Foresight, and Mechanical Filters The third in the Boatanchor SDR series — and the easiest of the three receivers to integrate with a modern spectrum display. Companion articles: This piece follows Choosing an SDR Front-End for the R-390A and Choosing an SDR Front-End for the… Read more: Choosing an SDR Front-End for the Collins 51S-1: Factory Outputs, Foresight, and Mechanical Filters

Choosing an SDR Front-End for the Hammarlund SP-600: Variants, Architectures, and Companions A variant-aware guide to pairing the Hammarlund Super-Pro 600 with a modern spectrum display — because the SP-600 you own may not be the SP-600 the other fellow on the forum owns. Companion article: This piece parallels the earlier Choosing an SDR Front-End… Read more: Choosing an SDR Front-End for the Hammarlund SP-600: Variants, Architectures, and Companions

Choosing an SDR Front-End for the R-390A: A Comparison Matrix A field guide for pairing the Cold War’s finest analog HF receiver with a modern spectrum display. The R-390A/URR was the most precise general-coverage HF receiver the US military ever produced, and seventy years on it remains a reference instrument. Its single-conversion-above-1-MHz architecture, crystal-calibrated PTO,… Read more: Choosing an SDR Front-End for the R-390A: A Comparison Matrix

RFI Analysis & Mitigation Engineering Guide VK6ADA — Boatanchor & Solid-State Technical Library Collins HF-380 Transceiver RFI Analysis & Mitigation Engineering Guide Internal emitters, external ingress paths, ferrite selection, and installation-grade RFI engineering for the military/commercial variant of the KWM-380. A structured 30-point suppression programme drawn from the Collins service bulletin record and modern EMI… Read more: Collins HF-380 Transceiver – RFI Analysis & Mitigation Engineering Guide

Collins Solid-State Restoration Series · Commercial / Government Variant Collins HF-380 Transceiver — Tantalum Capacitor Replacement Reference Guide A risk-prioritised service reference for the ~200-unit commercial/military variant of the KWM-380, with specific attention to the high-duty-cycle service profile that distinguishes the HF-380 from its amateur sibling. Companion document to the KWM-380 Tantalum Capacitor Replacement Reference… Read more: Collins HF-380 Transceiver — Tantalum Capacitor Replacement Reference Guide

Boatanchor Legends · Tribute Series Wayne Spring W6IRD · 1949–2025 Silent Key The west coast’s master of the Collins KWM-380 and HF-380, a Southern California DX Club president, and one half of ham radio’s most devoted husband-and-wife restoration team. Wayne Spring was one of those rare amateurs whose licensed career bridged the entire modern history… Read more: Wayne Spring – W6IRD

Spectrum Pollution · Advocacy Brief · April 2026 Starlink and the Silent Assault on the Low-Frequency Radio Spectrum How Unintended Electromagnetic Radiation from LEO Mega-Constellations Threatens Radio Astronomy, Weak-Signal Work, and the DX-er’s Night Sky — and What Amateur Radio Operators Can Do About It By Mike Peace VK6ADA — r-390a.net Administrator Executive Summary As… Read more: Starlink and the Silent Assault on the Low-Frequency Radio Spectrum

KWM-380 Tantalum Capacitor Replacement Reference Board-by-Board Location Guide, Risk Assessment & Replacement Recommendations Mike Peace VK6ADA • r-390a.net • vk6ada.com.au • April 2026 This reference accompanies the Collins KWM-380 RFI Analysis & Mitigation Guide. A site visitor asked for a practical list of tantalum capacitors and their board locations to simplify the replacement process. This… Read more: KWM-380 Tantalum Capacitor Replacement Reference

COLLINS KWM-380 RFI Analysis & Mitigation Guide A Comprehensive Engineering Reference for Reducing Noise Floor and Improving HF Signal-to-Noise Ratios Mike Peace VK6ADA • r-390a.net • vk6ada.com.au • April 2026 • Rev 1.0 1. Introduction The Rockwell Collins KWM-380 (introduced ~1979–1982) is a fundamentally different machine from the tube-era S-Line and KWM-2 equipment. It is… Read more: Collins KWM-380 RFI Analysis

Avionics History — Cold War Electronic Warfare The AN/APR-9B and AN/APA-70C on the AF-2W Guardian: Passive Radar Homing in Cold War ASW How the Grumman Guardian’s hunter variant used AIL/Collins electronic countermeasures equipment to detect, bear on, and home toward Soviet radar transmissions — SAC document confirmation, the probable APR-9B/APA-70C interface architecture, and the Shrike/ADI… Read more: The AN/APR-9B and AN/APA-70C on the AF-2W Guardian: Passive Radar Homing in Cold War ASW

R-390A Restoration Series — Power Supply Solid-State Replacement for the R-390A 26Z5W Rectifier Tubes Eliminating a critical obsolescence bottleneck in the PP-621/URR power supply — with full attention to B+ voltage compensation, heater string integrity, RFI suppression, and long-term reliability. Mike Peace VK6ADA  |  r-390a.net Administrator  |  vk6ada.com.au Introduction The Collins R-390A/URR is a receiver… Read more: Solid-State Replacement for the R-390A 26Z5W Rectifier Tubes

Collins 516F-2 Power Supply Transformer T1 Wire Identification Guide When the insulation fails and the colours disappear — mapping every winding from the inside out. A practical restoration reference for the CCA community The Problem The Collins 516F-2 power supply has served the S-Line family — KWM-2/2A transceivers and 32S-series transmitters — since the early… Read more: Collins 516F-2 Power Supply

Boatanchor Legends: Bob Sternowski, WB0LBI — From the Collins Radio Bench to Venus Boatanchor Legends — A Tribute Series Robert “Bob” Sternowski WB0LBI — Silent Key Collins Radio • Softronics Ltd. • NASA • HF Engineering Pioneer Bob Sternowski spent thirty-four years inside Collins Radio and its successor Rockwell Collins, rising to Director of Engineering… Read more: Robert “Bob” Sternowski, WB0LBI

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 Editorial Note Jan SP5XZG wrote a third time with several… Read more: The Complete Collins 618M Lineage

VK6ADA — Boatanchor Technical Library Care and Feeding of Power Grid Tubes in Vintage Collins Radio Equipment A Modern Reference Guide in the Spirit of Eimac’s Classic Application Bulletin Prepared April 2026  ·  Fact-Checked & Enriched Edition  ·  Mike Peace VK6ADA Table of Contents Foreword Collins Lineup Overview The 811A Triode — 30L-1 The 4X150A… Read more: Care and Feeding of Power Grid Tubes in Vintage Collins Radio Equipment

Collins Collectors Association — Technical Bulletin Commentary CCA Technical Bulletin 1 Understanding and Mitigating S-Line Transmitter Spikes BULLETIN REF: CCA-TB-001  ·  APPLIES TO: 32S-1 · 32S-3 · 32S-3A · KWM-2/2A  ·  COMMENTARY: VK6ADA, April 2026 ⚠ Priority Action Required — All 32S-3 / 32S-3A Owners If you do not know the complete modification history of… Read more: Understanding and Mitigating S-Line Transmitter Spikes

Collins 51J-4 Known Issues & Fault Diagnosis General-Coverage Receiver: PTO Endpoint Drift, Oil Tub Capacitor Failures, AVC Anomalies & Mechanical Filter Issues Community-documented problems and proven fixes for the Collins 51J-4 lab-grade general-coverage receiver — covering the 70E-15 PTO, F500B mechanical filter complement, 500 kHz IF system, and the 30-band front end About the 51J-4… Read more: Collins 51J-4 Known Issues & Fault Diagnosis

Collins S-Line Station Grounding & Bonding RF Ground, Audio Ground & Chassis Ground Are Three Different Things Incorrect bonding between the 75S-3, 32S-3, 312B-4, 30L-1, and 516F-2 is behind a significant proportion of hum, buzz, and RFI complaints — this guide explains the three ground domains, the interconnect cable ground paths, and the systematic approach… Read more: Collins S-Line Station Grounding & Bonding

Collins 32S-3 & 32S-3A Known Issues Transmitter-Specific: Carrier Balance Drift, ALC Time Constant, PA Neutralisation Loss & More Community-documented problems, factory service bulletins, and proven fixes for the most common S-Line transmitter restoration issues — the transmitter companion to the 75S-3/3A Known Issues guide About This Document The Collins 32S-3 (1962–1968) and 32S-3A (1968–1978) are… Read more: Collins 32S-3 & 32S-3A Known Issues

Web-888 SDR Integration Series National HRO-60 + Web-888 SDR Integration First Published SDR Integration Guide for the Iconic National Boatanchor The HRO-60 has no factory IF output and no existing SDR integration documentation — this guide provides the complete procedure for adding a high-impedance IF tap at 455 kHz and connecting the Web-888 SDR for… Read more: National HRO-60 + Web-888 SDR Integration

Collins 75S-3 & 75S-3A Known Issues Community-Documented Problems, Factory Service Bulletins & Proven Fixes AGC anomalies, product detector noise, PTO drift, bandswitch oxidation, frozen trimmers, Black Beauty capacitors, and the service bulletins that address them — a consolidated reference for the most common S-Line receiver restoration issues About This Document The Collins 75S-3 (1962–1968) and… Read more: Collins 75S-3 & 75S-3A Known Issues

Web-888 SDR Integration Series Collins 51J-4 Receiver + Web-888 SDR Integration The Easiest Integration in the Series — The 51J-4 Has a Factory 50Ω IF Output No internal modification required — the Collins 51J-4’s rear-panel IF OUTPUT connector (J104) provides a buffered 50Ω 500 kHz IF signal via a built-in V111 cathode follower, ready for… Read more: Collins 51J-4 Receiver + Web-888 SDR Integration

Collins S-Line AGC System Explained Delayed AGC with Separate Threshold, Dual Time-Constant Network & S-Meter Drive Understanding the 75S-3B/3C AGC loop is essential for diagnosing sensitivity and overload complaints — the AGC threshold, attack/decay time constants, noise clipper, and S-Meter transfer function explained from first principles with the Don Jackson analysis as primary reference Why… Read more: Collins S-Line AGC System Explained

Collins 32S-3 PA Neutralisation — Step by Step The Procedure Most Likely to Be Skipped — And Most Consequential When Wrong Definitive guide to 6146 PA neutralisation in the 32S-3/3A, KWM-2/2A, and 32S-1 — covering both the ceramic trimmer and air-variable circuits, the 6146B compatibility issue, oscilloscope technique, and the driver shield problem that kills… Read more: Collins 32S-3 PA Neutralisation — Step by Step

Collins KWM-2/2A Carrier Balance Optimisation Suppressed Carrier Level Directly Affects Transmit Audio Quality The two-stage carrier suppression architecture, the balanced modulator null procedure, the first balanced mixer trim, and why the manual procedure is poorly explained — with a clear step-by-step approach that actually works Why Carrier Balance Matters for Audio Quality Carrier balance is… Read more: Collins KWM-2/2A Carrier Balance Optimisation

Collins S-Line ALC System — Theory, Faults & Wiring How the ALC Loop Works Across the S-Line Station: 75S-3C + 32S-3A + 30L-1 Common ALC interaction faults, the KWM-2A ALC connector wiring, and the complete signal flow from microphone to legal limit What ALC Does — And Why It Matters Automatic Level Control (ALC) is… Read more: Collins S-Line ALC System — Theory, Faults & Wiring