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Collins Radio Avionics —Historical Introduction Dates A Research Memorandum • 618M VHF COM • 51R-7A • 51R-8A • VIR-30 • 860E DME • DME-40 • 51RV • Solid State System (1963) • Pro Line I (early 1970s) • Collins Radio Company, Cedar Rapids IA • Prepared in response to a reader enquiry 📝 VK6ADA Research… Read more: Collins Radio Avionics – Historical Introduction Dates

Collins KWM-2 / KWM-2ARestoration Deep-Dive Arthur Collins’ Masterpiece • 1959–1977 • The Compact S-Line That Went to War Of all the rigs to emerge from Cedar Rapids, Iowa during the golden age of amateur radio engineering, the Collins KWM-2 occupies a singular position. It was the world’s first commercially produced amateur mobile SSB transceiver, it… Read more: Collins KWM-2 / KWM-2A Restoration Deep-Dive

Alpha 87A Linear Amplifier:Restoration & Service Guide 3CX800A7 Tubes • PIN Diode T/R Switching • Microprocessor Control • Fault Code Reference • Cabinet & Safety 📝 VK6ADA Technical Papers 📅 March 2026 ⚡ 1,500 W Continuous — 3CX800A7 💻 Microprocessor Controlled Autotune ⚠ High Voltage Equipment Abstract. The Alpha 87A is a microprocessor-controlled, self-tuning HF linear… Read more: Alpha 87A Linear Amplifier: Restoration & Service Guide

Alpha / ETO 91B Linear Amplifier:Restoration & Service Guide 4CX800A/GU74b Tetrodes • Grounded-Cathode Grid-Driven • Vacuum Relay QSK • Electronic Bias System • Cabinet & Safety 📝 VK6ADA Technical Papers 📅 March 2026 ⚡ 1,500 W — 4CX800A/GU74b Tetrode 🇧🇬 Assembled in Bulgaria ⚠ High Voltage Equipment Abstract. The Alpha/ETO 91B is a manual-tune HF linear… Read more: Alpha / ETO 91B Linear Amplifier: Restoration & Service Guide

Alpha 9500 Linear Amplifier:Restoration & Service Guide 3CX1500A7/8877 Triode • Five I²C Microprocessors • Auto Mains Tap • Gigavac Vacuum Relays • Three Stepper Motors • Cabinet & Safety 📝 VK6ADA Technical Papers 📅 March 2026 ⚡ 1,500 W — 3CX1500A7/8877 Triode 💻 5 × Microprocessors / I²C Bus 🇺🇸 Made in Colorado, USA ⚠ High… Read more: Alpha 9500 Linear Amplifier: Restoration & Service Guide

Alpha 8410 Linear Amplifier:Restoration & Service Guide 4CX1500B Bayonet Tetrodes • Manual Tune • Swamped-Grid Input • EBS • PIC Microcontroller • Dual Input Match Relay • Cabinet & Safety 📝 VK6ADA Technical Papers 📅 March 2026 ⚡ 1,500 W — 2× 4CX1500B Tetrode 🔄 Manual Tune / Manual Mains Tap 🇺🇸 Made in Colorado, USA… Read more: Alpha 8410 Linear Amplifier: Restoration & Service Guide

Emtron DX-1A Linear Amplifier:Restoration & Service Guide GU74B (4CX800A) Tetrode • AMPC Control Board • TRIAC Soft-Start • EBS Jumper • Optional Jennings QSK • Emona Electronics Sydney • Cabinet & Safety 📝 VK6ADA Technical Papers 📅 March 2026 ⚡ 750 W avg / 1,000 W PEP — GU74B Tetrode 🇦🇺 Made in Sydney, Australia 🔄 Manual… Read more: Emtron DX-1A Linear Amplifier: Restoration & Service Guide

Emtron DX-1D Linear Amplifier:Restoration & Service Guide GU74B (4CX800A) Tetrode • RF Sub-Chassis & 9-Way Connector • Dedicated Display Board • SWR Protection • AMPC Control Board • TRIAC Soft-Start • TDA1085C • Dual Tank Coils • Emona Electronics Sydney 📝 VK6ADA Technical Papers 📅 March 2026 ⚡ 750 W avg / 1,000 W PEP — GU74B… Read more: Emtron DX-1D Linear Amplifier: Restoration & Service Guide

Emtron DX-1SP Linear Amplifier:Restoration & Service Guide FU-728F (4CX1500B-class) Tetrode • 1,200 W CW / 1,500 W PEP • 8× 470 μF/500 V HV Bank • 40 A TRIAC Soft-Start • Dual-Polarity Screen Protection • Eimac 4CX1500B Compatible • OCC • FCC Approved 📝 VK6ADA Technical Papers 📅 March 2026 ⚡ 1,200 W CW / 1,500 W PEP — FU-728F Tetrode 🇦🇺… Read more: Emtron DX-1SP Linear Amplifier: Restoration & Service Guide

Emtron DX-1V Linear Amplifier:Restoration & Service Guide 6-Metre (50 MHz) Specialist Variant • GU74B (4CX800A) Tetrode • Single-Band 50 MHz Pi-Network • AMPC Control Board • TRIAC Soft-Start • QSK Standard • Emona Electronics Sydney 📝 VK6ADA Technical Papers 📅 March 2026 🇒 50 MHz (6 Metres) — GU74B Tetrode 🇦🇺 Made in Sydney, Australia 🔄 Single-Band /… Read more: Emtron DX-1V Linear Amplifier: Restoration & Service Guide

Emtron DX-2 Linear Amplifier:Restoration & Service Guide GU84B (4CX2500A) Tetrode • 27 V Heater • 1,500 W Carrier / 7 Bands • Ferrite Toroid “L” Coil • Two-Speed Blower • Ig2+/Ig2− Screen Current Metering • RF Sub-Chassis • 9-Way Connector • Emona Electronics Sydney 📝 VK6ADA Technical Papers 📅 March 2026 ⚡ 1,500 W carrier — GU84B /… Read more: Emtron DX-2 Linear Amplifier: Restoration & Service Guide

Emtron DX-2A Linear Amplifier:Restoration & Service Guide GU84B (4CX2500A) Tetrode • 9-Band Full Coverage (160m–10m incl. WARC) • RF Module Schematic in DX-1D Documentation • Two-Speed Blower • Dual Temperature Sensors • All-Band Tank Circuit Upgrade • Emona Electronics Sydney 📝 VK6ADA Technical Papers 📅 March 2026 ⚡ 1,500 W carrier — GU84B / 4CX2500A 🇦🇺… Read more: Emtron DX-2A Linear Amplifier: Restoration & Service Guide

Emtron DX-2SP Linear Amplifier:Restoration & Service Guide GU84B  •  2,000 W Carrier / 2,500 W PEP  •  4 kVA Transformer  •  Heavy-Duty H.V./H.C. Band Switch  •  Horizontal AMPC Board  •  Dual-Polarity Screen Supply  •  BTA40-600B TRIAC Soft-Start  •  9 Bands 160m–10m incl. WARC  •  Later Production: FU-728F Tetrode Option 📝 VK6ADA Technical Papers 📅 March 2026 ⚡ 2,000 W carrier… Read more: Emtron DX-2SP Linear Amplifier: Restoration & Service Guide

Emtron DX-2V Linear Amplifier:Restoration & Service Guide GU84B (4CX2500A) Tetrode • 6‑Metre Specialist (50 MHz) • 2,000 W Output • Single‑Band 50 MHz Pi‑Network • Dedicated 50 MHz Plate Choke • Parasitic Suppression Critical • QSK Standard • Debut: Dayton Hamvention 2010 • Emona Electronics Sydney 📝 VK6ADA Technical Papers 📅 March 2026 ⚡ 2,000 W — GU84B on 50 MHz… Read more: Emtron DX-2V Linear Amplifier: Restoration & Service Guide

Emtron DX-3 Linear Amplifier:Restoration & Service Guide GU78B (4CX3000A) Tetrode • 3,000 W Carrier / 4,000 W PEP • 9 Bands 160m–10m incl. WARC • Dual-Fan Cooling • 700 µH Plate Choke • Horizontal AMPC Board • QSKv3 (Two Relay Options) • 60–90 W Drive • Transformer & RF Deck Shipped Separately • 43 kg Total • Emona Electronics Sydney… Read more: Emtron DX-3 Linear Amplifier: Restoration & Service Guide

Emtron DX-3SP Linear Amplifier:Restoration & Service Guide Two FU-728F Tetrodes in Parallel • 4,000 W Carrier / 5,000 W PEP • 3,400 V DC Plate Supply • 9 Bands 160m–10m incl. WARC • Three Bias Pots (POT3 + POT10/BS1 + POT9/BS2) • Safety Choke • Mains Isolation Relay • 3,300 pF/10 kV Bypass • Turbine + Two Suction Fans • 50 kg •… Read more: Emtron DX-3SP Linear Amplifier: Restoration & Service Guide

Emtron DX-4 Linear Amplifier:Restoration & Service Guide Two GU84B (4CX2500A) Tetrodes in Parallel • 4,000 W Carrier / 5,000 W PEP • 3,100 V DC Plate Supply • Separate Standalone HV Power Supply (3 Variants) • Three-Interlock Serial Safety Chain • Auxiliary Transformer in RF Deck • 117 µF HV Filter (Single-Phase) • Two QSK Vacuum Relays • 9 Bands… Read more: Emtron DX-4 Linear Amplifier: Restoration & Service Guide

Henry Radio HF Linear Amplifiers:Omnibus Restoration & Service Guide All HF Tube & Solid-State Models • 2K/3K/4K/5K/8K Series • 1963–2005 • Los Angeles, California • Grounded-Grid Triodes • 3-400Z • 3-500Z • 8873/8874/8877 • 3CX1200A7/D7 • 3CX3000A7 • 5CX1500A • Pi-Network & Continuously Variable Tuning • Console, Desk, 1-Piece, 2-Piece & Remote-Tune Configurations • SS500/750/1200HF… Read more: Henry Radio HF Linear Amplifiers: Omnibus Restoration & Service Guide

Heathkit SB-200 Linear Amplifier:Complete Restoration Guide Circuits • Cabinet • Safety • Component Replacement • Modern Upgrades • SB-201 Coverage 📝 VK6ADA Technical Papers 📅 March 2026 ⚡ 572B Triode — 600 W Class ⚠ High Voltage Equipment Abstract. The Heathkit SB-200 is a grounded-grid HF linear amplifier produced from 1964 to 1978, rated at approximately… Read more: Heathkit SB-200 Linear Amplifer Restoration Guide

Heathkit SB-220 Linear Amplifier:Complete Restoration Guide Circuits • Cabinet • Safety • Component Replacement • Modern Upgrades 📝 VK6ADA Technical Papers 📅 March 2026 ⚡ 2 kW Class — 3-500Z Triode ⚠ High Voltage Equipment Abstract. The Heathkit SB-220 is a grounded-grid HF linear amplifier first produced in 1969, rated at approximately 1,200–1,500 W PEP output… Read more: Heathkit SB-220 Linear Amplifier Restoration Guide

Community Join the Vintage AmateurRadio Restoration Group A dedicated mailing list for amateurs who restore, study, and operate vintage HF equipment — Collins, National, Hammarlund, Hallicrafters, Drake, Heathkit, and beyond. Technical advice, restoration notes, and a community that values doing it properly. ◆ Hosted on Groups.io ◆ Free to join ◆ Low-traffic, high-signal What the… Read more: Join the Vintage Amateur Radio Restoration Group

Collins 180S-1 Jumper Plug Engineering Design | VK6ADA VK6ADA vk6ada.com.au  •  r-390a.net Collins S-Line — Engineering Design Document Collins 180S-1Jumper Plug Reproduction A comprehensive engineering design for fabricating reproduction jumper plugs for the Collins 180S-1 antenna tuner — including circuit analysis, RF electrical requirements, dimensional specification, parts list, vendor sources, assembly instructions, and critical corrections… Read more: Collins 180S-1 Jumper Plug Reproduction

Collins 180S-1 Antenna Tuner Restoration Guide | VK6ADA VK6ADA vk6ada.com.au  •  r-390a.net Collins S-Line Accessories Restoration Series Collins 180S-1Antenna Tuner Restoration Guide A complete field guide to the cosmetic and mechanical restoration of the Collins 180S-1 pi-network antenna tuner — covering front panel and cabinet finishing, vacuum variable capacitor inspection, roller inductor servicing, switch and… Read more: Collins 180S-1 Antenna Tuner Restoration Guide

R-390/URR Restoration Guide | VK6ADA VK6ADA vk6ada.com.au  •  r-390a.net Collins Military Receiver Restoration Series R-390/URR ReceiverRestoration Guide A complete field guide to the cosmetic and mechanical restoration of the Collins R-390/URR military HF communications receiver — covering disassembly, the critical green gearwheel procedure, cabinet refinishing, panel marking restoration, hardware, and CCA grading. This guide covers… Read more: Collins R390 Receiver Restoration Guide

R-390A/URR Restoration Guide | VK6ADA VK6ADA vk6ada.com.au  •  r-390a.net Collins Military Receiver Restoration Series R-390A/URR ReceiverRestoration Guide A complete field guide to the cosmetic restoration of the R-390A/URR military HF communications receiver — covering disassembly, haze gray finish specification, panel marking restoration, hardware treatment, manufacturer variations, and achieving CCA grading standards. ✎ Mike Peace VK6ADA… Read more: Collins R390A Receiver Restoration Guide

Hammarlund SP-600 Restoration Guide | VK6ADA VK6ADA vk6ada.com.au  •  r-390a.net Boatanchor Receiver Restoration Series Hammarlund SP-600Restoration Guide A complete field guide to the cosmetic and mechanical restoration of the Hammarlund SP-600 series military HF communications receiver — covering variant identification, the Black Beauty capacitor problem, front panel refinishing, the dial slippage cure, panel marking restoration,… Read more: Hammarlund Super Pro SP-600 Restoration Guide

R-388/URR Restoration Guide | VK6ADA VK6ADA vk6ada.com.au  •  r-390a.net Collins Military Receiver Restoration Series R-388/URR ReceiverRestoration Guide A complete field guide to the cosmetic and mechanical restoration of the Collins R-388/URR military HF communications receiver — covering disassembly, paint stripping, cabinet refinishing, panel marking restoration, hardware, and achieving CCA grading standards. ✎ Mike Peace VK6ADA… Read more: Collins R-388 Receiver Cabinet Restoration

Collins S-Line Cabinet & Trim Restoration Guide | VK6ADA VK6ADA vk6ada.com.au  •  r-390a.net Collins S-Line Restoration Series Cabinet, Bezel & Trim Restorationfor the Collins S-Line A complete field guide to restoring Collins S-Line cabinets, front-panel bezels, and all associated trim hardware to factory appearance — covering disassembly, chemical stripping, primer selection, painting, and achieving CCA… Read more: Collins S-Line Cabinet Restoration

If you own or are restoring a Hammarlund SP-600, one resource you need to know about is Perry Sandeen’s An Anthology of Technical References for the Hammarlund SP-600 and its Variants. This is a comprehensive compilation covering the SP-600 receiver family and its many variants, assembled over a long period with contributions from numerous collectors and… Read more: Perry Sandeen’s Hammarlund SP-600 Anthology 

VK6ADA  ·  Mike Peace  ·  Vintage Collins Radio  ·  r-390a.net Home › Collins Vintage Radio › Collins KWM-2 / KWM-2A Serial Number Guide Collins KWM-2 / KWM-2A — Serial Number & Production Guide VK6ADA Technical Reference  ·  Collins Vintage Amateur Transceivers  ·  March 2026  ·  Mike Peace VK6ADA The Collins KWM-2 is widely regarded as… Read more: Collins KWM-2 / 2A Transceiver Serial Number Guide

VK6ADA  ·  Mike Peace  ·  Vintage Collins Radio  ·  r-390a.net Home › Collins Vintage Radio › Collins KWM-1 / KWM-1A Serial Number Guide Collins KWM-1 / KWM-1A — Serial Number & Production Guide VK6ADA Technical Reference  ·  Collins Vintage Amateur Transceivers  ·  March 2026  ·  Mike Peace VK6ADA The Collins KWM-1 holds a unique place… Read more: Collins KWM-1 / 1A Transceiver Serial Number Guide

Collins 75S-3 / 75S-3B / 75S-3C Receiver Serial Number Guide – VK6ADA VK6ADA  ·  Mike Peace  ·  Vintage Collins Radio  ·  r-390a.net Home › Collins S-Line › Collins 75S-3 / 75S-3B / 75S-3C Serial Number Guide Collins 75S-3 / 75S-3B / 75S-3C — Serial Number & Production Guide VK6ADA Technical Reference  ·  Collins S-Line Vintage… Read more: Collins 75S-3 Serial Number Guide

Collins 75S-2 Receiver Serial Number Guide – VK6ADA VK6ADA  ·  Mike Peace  ·  Vintage Collins Radio  ·  r-390a.net Home › Collins S-Line › Collins 75S-2 (RARE) › Serial Number Guide Collins 75S-2 — Serial Number & Production Guide VK6ADA Technical Reference  ·  Collins S-Line Vintage Amateur Equipment  ·  March 2026  ·  Mike Peace VK6ADA ⭐… Read more: Collins 75S-2 Serial Number Guide

Collins 75S-1 Receiver Serial Number Guide – VK6ADA VK6ADA  ·  Mike Peace  ·  Vintage Collins Radio  ·  r-390a.net Home › Collins S-Line › Collins 75S-1 Serial Number Guide Collins 75S-1 — Serial Number & Production Guide VK6ADA Technical Reference  ·  Collins S-Line Vintage Amateur Equipment  ·  March 2026  ·  Mike Peace VK6ADA The Collins 75S-1… Read more: Collins 75S-1 Receiver Serial Number Guide

Collins 32S-3 Transmitter Serial Number Guide – VK6ADA VK6ADA  ·  Mike Peace  ·  Vintage Collins Radio  ·  r-390a.net Home › Collins S-Line › Collins 32S-3 Serial Number Guide Collins 32S-3 — Serial Number & Production Guide VK6ADA Technical Reference  ·  Collins S-Line Vintage Amateur Equipment  ·  March 2026  ·  Mike Peace VK6ADA The Collins 32S-3… Read more: Collins 32S-3 Transmitter Serial Number Guide

Collins 32S-2 Transmitter Serial Number Guide – VK6ADA VK6ADA  ·  Mike Peace  ·  Vintage Collins Radio  ·  r-390a.net Home › Collins S-Line › Collins 32S-2 Serial Number Guide Collins 32S-2 — Serial Number & Production Guide VK6ADA Technical Reference  ·  Collins S-Line Vintage Amateur Equipment  ·  March 2026  ·  Mike Peace VK6ADA Collector Note —… Read more: Collins 32S-2 Transmitter Serial Number Guide

Collins 32S-1 Transmitter Serial Number Guide – VK6ADA VK6ADA  ·  Mike Peace  ·  Vintage Collins Radio  ·  r-390a.net Home › Collins S-Line › Collins 32S-1 Serial Number Guide Collins 32S-1 — Serial Number & Production Guide VK6ADA Technical Reference  ·  Collins S-Line Vintage Amateur Equipment  ·  March 2026  ·  Mike Peace VK6ADA The Collins 32S-1… Read more: Collins 32S-1 Transmitter Serial Number Guide

◆ VK6ADA · r-390a.net · Topic Index Hollow State NewsletterComplete Topic Index The Community Archive — Unlocked & Indexed Editor: Les Locklear  •  Gulfport, Mississippi  •  ~1993–2001 53Issues 7Yrs Run 30+Contributors 18Topic Cats The Hollow State Newsletter (HSN) was the primary technical publication of the R-390A community from its founding by Les Locklear of Gulfport,… Read more: Hollow State Newsletter – Complete Topic Index

SDR Resource Guide · vk6ada.com.au OpenWebRX+ · Primary Websites & Resources Web-based Software Defined Radio — The Enhanced Fork OpenWebRX+ is an enhanced community fork of the original OpenWebRX web-based software-defined radio application. It extends the upstream project with additional demodulators, a built-in scanner, noise reduction, keyboard shortcuts, improved maps, and decoders for a wide… Read more: OpenWebRX+ Resources

Bill Orr W6SAI — Amateur Radio Legend | VK6ADA VK6ADA · Boatanchor Legends Series Bill Orr W6SAI Engineer · Educator · Author · Amateur Radio Legend 1919 – 2001  |  W2HCE / W6SAI  |  DXCC Honor Roll  |  OSCAR-1 Pioneer 📝 Mike Peace VK6ADA 🌐 r-390a.net Administrator 📅 Published March 2026 📖 Boatanchor Legends —… Read more: Bill Orr W6SAI – Biography

Collins 30L-1 Serial Number Guide – VK6ADA VK6ADA Mike Peace  ·  Vintage Collins Radio  ·  r-390a.net Home › Collins 30L-1 Amplifier › Serial Number Guide Collins 30L-1 — Serial Number & Production Guide VK6ADA Technical Reference  ·  Collins S-Line Vintage Amateur Equipment  ·  March 2026  ·  Mike Peace VK6ADA The Collins 30L-1 RF Linear Amplifier… Read more: Collins 30L-1 Ampifier Serial Number Guide

Collins 51S-1 / 1A / 1F / 1AF / 1B — AM, CW & SSB Receiver A comprehensive engineering analysis of RFI mitigation strategies, ferrite core selection, noise reduction techniques, and signal-to-noise ratio improvements for the Collins 51S-1 series receivers. Covers nine modification intercept points across the signal chain, power supply, and oscillator subsystems. The… Read more: Collins 51S-1 / 1A / 1F / 1AF / 1B — AM, CW & SSB Receiver RFI Mitigation Strategies

Technical Whitepaper · VK6ADA · r-390a.net Rebuilding & Upgrading the Collins S-Line70K-2 Permeability-Tuned Oscillator (PTO) Modern Component Substitution · RFI Mitigation · Ferrite Core Techniques · Signal-to-Noise Improvement 75S-1 75S-2 75S-3 75S-3B 75S-3C/m 32S-1 32S-2 32S-3 KWM-2 KWM-2A AUTHOR Mike Peace VK6ADA · r-390a.net Administrator SITE vk6ada.com.au DATE March 2026 SKILL LEVEL Intermediate–Advanced REF Collins… Read more: Rebuilding & Upgrading the Collins S-Line70K-2 Permeability-Tuned Oscillator (PTO)

Enhancing the Collins 180S-1 Antenna Tuner: Complementary Balun Designs Products for Modern HF Operation Technical White Paper — Collins S-Line Restoration & Integration Series 📝 VK6ADA Technical Papers 📅 March 2026 🔌 HF Antenna Systems ⚡ 1 kW Class Abstract. The Collins 180S-1 Antenna Tuner is a 1 kW pi-network matching unit covering 3–30 MHz, designed to… Read more: Enhancing the Collins 180S-1 Antenna with Complementary Balun Designs Products

Collins 75S-3 — BFO Sideband Tolerance Reduction: Design Options Engineering Design Study — Collins S-Line Series Collins 75S-3 ReceiverBFO Sideband Tolerance Reduction Design Options to Reduce USB / LSB Dial Offset — Component Changes, Circuit Modifications, and Modern Replacement Strategies Equipment: Collins 75S-3 / 75S-3B / 75S-3C Reference: KI-75S3-001 Classification: Engineering Design Study Rev 1.0… Read more: Collins 75S-3 Receiver BFO Sideband Tolerance Reduction

Collins 75S-3 Receiver – Known Issue: USB/LSB BFO Dial Offset Known Issue — Collins S-Line Series Collins 75S-3 ReceiverUSB / LSB BFO Dial Offset Tunable BFO “Zero” Position Differs Between Sidebands — Normal Tolerance Behaviour vs. Alignment Fault Equipment: Collins 75S-3 / 75S-3B / 75S-3C Issue ID: KI-75S3-001 Severity: Informational — No Fault Rev 1.0… Read more: Collins 75S-3 Receiver – BFO sideband offset tolerance

Single-Band Loss: Symptom Analysis, Root Cause Diagnosis & Troubleshooting Collins Radio · Technical Reference Series Collins 32S-3 Transmitter Single-Band Loss: Symptom Analysis, Root Cause Diagnosis & Troubleshooting 80 METRES VFO INJECTION 1ST MIXER BAND SWITCH Reported Case Summary All three 80 metre band positions are non-functional. The transmitter exhibits identical symptoms whether operated from its… Read more: Collins 32S-3 Transmitter

Antenna Engineering Guide · Collins S-Line · Balun Designs Multiband HF Loop Antennas with the Collins 180S-1 Tuner, Balun Designs Model 4114 and Model 1115d Impedance Transformation, Common-Mode Suppression & Practical Installation for 160–10 Metre Operation by Mike Peace VK6ADA  ·  r-390a.net Administrator March 2026 Document Version 1.1 Contents Executive Summary Introduction Collins 180S-1 Antenna… Read more: Multiband HF Loop Antennas with the Collins 180S-1 Tuner, Balun Designs Model 4114 and Model 1115d

Collins KWM-2A Transceiver RFI Mitigation & Receiver Noise Reduction Ferrite Cores, Inductors, Filtering & Grounding Modifications for the Modern Noise Environment Mike Peace  VK6ADA  •  r-390a.net Administrator 1. Executive Summary The Collins KWM-2A is a double-conversion SSB/CW transceiver covering 3.4–30.0 MHz, produced by Collins Radio Company from 1961 to 1979.[1] It represents the pinnacle of 1960s… Read more: Collins KWM-2A HF Transceiver RFI Analysis and Receiver Noise Mitigation

Collins 312B-3 Speaker Cabinet Bluetooth Speaker Conversion Dual-Mode DC / Li-Ion Battery Power · Bluetooth 5.0 aptX HD · Dayton Audio KAB-250v4 + LBB-5Sv2 · Ferrite RFI Suppression Mike Peace VK6ADA  ·  r-390a.net Administrator  ·  March 2026 1. Project Overview This post documents a complete Bluetooth audio upgrade for the Collins 312B-3 speaker cabinet, adding… Read more: Collins 312B-3 Speaker – Bluetooth Conversion

Collins 516F-2 Speaker Cabinet Bluetooth Speaker Conversion Dual-Mode AC / Li-Ion Battery Power · Bluetooth 5.0 aptX HD · Dayton Audio KAB-250v4 + LBB-5Sv2 · Ferrite RFI Suppression Mike Peace VK6ADA  ·  r-390a.net Administrator  ·  March 2026 1. Project Overview This post documents a complete Bluetooth audio upgrade for the Collins 516F-2 speaker cabinet, adding… Read more: Collins 516F-2 speakers – Bluetooth Conversion

Collins MP-1 Power SupplyComplete Restoration Kit For the S-Line · KWM-2 · KWM-2A  |  Includes RFI Mitigation Ferrite Package 47 Components 100% USA Sourcing Ships from Missouri 6Kit Sections 47Components 6US Vendors 4Ferrite Types The Collins MP-1 mobile power supply has been out of production for over five decades. The original design used selenium rectifiers,… Read more: Collins MP-1 power supply restoration kit

Collins 136B-2 Noise Blanker Engineering Changes & Circuit Modifications Reference Collins 136B-2 Noise Blanker Engineering Changes & Circuit Modification Reference Covering factory-issued changes, community-developed improvements, alignment notes, antenna adaptation, and advanced modifications for contemporary fixed-station use. 1. Background & Design Overview The Collins 136B-2 is a stand-alone noise blanker accessory designed to operate with the… Read more: Collins 136B-2 Noise Blanker for the KWM-2 and KWM-2A Transceivers

Engineering Reference Document Collins 516F-2 Power Supply RFI Analysis & Mitigation Engineering Guide Noise Floor Reduction Strategies for Collins S-Line, KWM-2, and KWM-2A HF Station Installations Prepared by Mike Peace VK6ADA  |  r-390a.net Administrator  |  Document Revision 2.0 — February 2026  |  Engineering Reference • Not For Resale Contents Introduction and Scope Collins 516F-2 Circuit… Read more: Collins 516F-2 Power Supply RFI Analysis and Mitigation

Vintage Hammarlund · Restoration Guide Hammarlund SP-600 JX-16 Complete Restoration, Alignment & RFI Mitigation Guide Mike Peace VK6ADA  ·  r-390a.net Administrator Parameter Specification Frequency Coverage 0.54 – 54 MHz in 6 bands Conversion Double conversion (above 7 MHz); single below 1st IF 3.955 MHz 2nd IF 455 kHz Sensitivity (AM) < 1 µV for 10… Read more: Hammarlund SP-600 JX-16 Restoration Guide

Mission RGO ONE · Technical Guide RGO ONE HF Transceiver RFI Mitigation, Receiver Noise Reduction & Signal-to-Noise Ratio Improvement Guide Mike Peace VK6ADA  ·  r-390a.net Administrator Field Detail Author Mike Peace, VK6ADA Website vk6ada.com.au Resource r-390a.net Transceiver Mission RGO ONE — All Series / Production Lots Document Type Technical Modification Guide Applies To Series 1–6… Read more: RGO ONE Transceiver RFI Mitigation

Collins 32S-1 Transmitter

Boatanchor Legends — A Tribute Series Matt Parkinson is one of the credited contributors to “The 21st Century R-390A/URR Technical Reference” — the Y2K Manual — the document that transformed the R-390A from an equipment type served by scattered, aging military manuals into one supported by a comprehensive, community-built technical reference. His name appears in… Read more: Matt Parkinson

HSN Founding Editor & R-390A Historian • Gulfport, Mississippi The Founding Editor Les Locklear of Gulfport, Mississippi is one of the foundational figures of the modern R-390A community. As the original editor of the Hollow State Newsletter, he shepherded the publication through approximately 50 issues over seven years — an extraordinary run for a niche… Read more: Les Locklear

K1LKY — R-390 Restoration Authority & NIST Engineer The Professional Engineer Roy Morgan, K1LKY (of Western Massachusetts, formerly at the National Institute of Standards and Technology), brought professional-grade engineering discipline to the R-390 community. His restoration guidelines for the R-390 (non-A) receiver became a foundational reference — a systematic, no-nonsense checklist that remains hosted at… Read more: Roy Morgan