◆ VK6ADA · r-390a.net · Topic Index

Hollow State Newsletter
Complete 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, Mississippi. For approximately seven years the newsletter shepherded the collective technical knowledge of the world’s most dedicated community of military receiver restorers — alignment procedures, modification designs, DSP applications, parts sourcing, historical research, and restoration standards that no other publication captured.

This index maps all 53 issues by article title, author, and subject category. Use the search box and topic cross-reference to navigate the archive. For the digital archive itself, see the HSN Archive page.

Index compilation note: This topic index was compiled from the HSN archive, the r-390a.net Pearls of Wisdom collection, community-contributed article lists, and the R-390 reflector archive. Entries marked with ‡ are reconstructed from community citations and secondary references where original pagination was not directly verifiable. Callsigns and affiliations are credited as they appeared in the original issues. Index compiled by Mike Peace VK6ADA · r-390a.net Administrator.

Filter index: Filters the table below in real-time — works on article titles, authors, and topics.

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Issues 1–8 Issues 9–18 Issues 19–28 Issues 29–38 Issues 39–53 Topic Cross-Ref Author Index Footnotes

Topic Tag Legend

AGC ALIGNMENT AUDIO BFO DSP IF FILTER HISTORY MECHANICAL POWER SUPPLY PTO RESTORATION RECEIVER SSB TUBES TEST EQUIP PARTS CW SP-600 R-390

Issues 1–8 Founding Year · circa 1993–1994

Issue	Article / Topic	Author	Subject Tags
► Issue No. 1 — Inaugural Issue, circa late 1993
1	Welcome to the Hollow State Newsletter — Editorial introduction; scope, aims, and readership of the newsletter; call for contributions from the R-390A community	Les Locklear^¹	HISTORY RECEIVER
1	R-390A Overview and Community Background — History of the Collins R-390A/URR military receiver; MILSPEC overview; why the receiver has attracted such a dedicated restoration community	Les Locklear^¹	HISTORY RECEIVER
1	First Steps in R-390A Restoration — Safety precautions; initial visual inspection; power-up procedure; preliminary functional checks for a receiver of unknown provenance	Chuck Rippel WA4HHG^²	RESTORATION RECEIVER
1	The R-390A PTO — A Preliminary Look — Introduction to the permeability-tuned oscillator; common faults; temperature compensation issues ‡	Les Locklear^¹	PTO
► Issue No. 2 — circa early 1994
2	R-390A Restoration Procedure — Part 1: RF Deck — Systematic restoration checklist for the RF deck; inspection points; common component failures; contact cleaning	Chuck Rippel WA4HHG^²	RESTORATION ALIGNMENT
2	Power Supply Restoration in the R-390A — Electrolytic capacitor replacement; rectifier tube and diode substitution; voltage rail checks; filter capacitor sizing	Jack Burchett^³	POWER SUPPLY RESTORATION
2	Calibrator Section Overview and Troubleshooting — 100 kHz crystal calibrator; common faults; tube substitutions; frequency accuracy verification ‡	Les Locklear^¹	ALIGNMENT TUBES
2	Parts Sourcing for R-390A Restoration — 1994 Edition — Current vendors; obsolescence issues; military surplus sources; substitution notes for hard-to-find components	Community contributors^⁷	PARTS RESTORATION
► Issue No. 3 — circa mid 1994
3	R-390A IF Alignment — Theory and Practice — Complete IF alignment procedure for all five IF amplifier stages; mechanical filter passband optimisation; bandwidth switching verification	Chuck Rippel WA4HHG^²	ALIGNMENT IF FILTER
3	Understanding the R-390A Mechanical Filters — Collins mechanical bandpass filters; 500 Hz, 1 kHz, 2 kHz, 4 kHz, 8 kHz; insertion loss measurements; deterioration signs; sourcing replacements	Dr. Dallas Lankford^⁴	IF FILTER RECEIVER
3	Gear Train Disassembly and Lubrication — Step-by-step disassembly of the R-390A mechanical dial drive; lubrication specifications; reassembly and backlash adjustment ‡	Richard Biddle^¹²	MECHANICAL RESTORATION
3	The Audio System in the R-390A — Audio amplifier circuit; substitution options for 12AX7 driver and audio output tube; speaker impedance matching ‡	Jack Burchett^³	AUDIO TUBES
► Issue No. 4 — circa late 1994
4	PTO Rebuild — Detailed Procedure — Complete disassembly, cleaning, and reassembly of the R-390A PTO; slug inspection; coil form cleaning; stability measurements before and after	Chuck Rippel WA4HHG^²	PTO RESTORATION
4	R-390A BFO — Modification for SSB Reception — BFO injection level optimisation; sideband selection; LSB/USB offset adjustment; beating carrier injection techniques	Dr. Dallas Lankford^⁴	BFO SSB
4	R-390 (Non-A) Restoration Overview — Differences between the R-390 and R-390A; restoration priorities specific to the non-A variant; parts interchangeability guide ‡	Roy Morgan K1LKY^⁵	R-390 RESTORATION
4	AGC System Analysis — Part 1 — Automatic gain control circuit topology in the R-390A; time constant measurements; AGC range; known deficiencies in stock design	Dr. Dallas Lankford^⁴	AGC RECEIVER
► Issue No. 5 — circa early 1995
5	R-390A Restoration — Part 2: IF Deck and Mechanical Filters — Continued restoration checklist; IF bandswitch contacts; mechanical filter inspection; filter substitution options	Chuck Rippel WA4HHG^²	RESTORATION IF FILTER
5	AGC System Analysis — Part 2: Modifications — Proposed AGC time-constant modifications; threshold adjustments; diode replacement for improved low-signal AGC action	Dr. Dallas Lankford^⁴	AGC RESTORATION
5	Using Test Equipment with the R-390A — Recommended test instruments; signal generator requirements; audio analyser use; VTVM and digital meter considerations for high-impedance circuits	Larry Haney^⁶	TEST EQUIP ALIGNMENT
5	Manufacturer Variants — Spotting a Collins vs. EAC vs. Motorola R-390A — Visual identification guide for the five principal R-390A manufacturers; key external and internal differences ‡	Randy Stout^¹³	HISTORY RECEIVER
► Issue No. 6 — circa mid 1995
6	RF Alignment Procedure — Complete Step-by-Step — Complete R-390A RF alignment with peaking procedure; proper injection levels; trimmer adjustments by band segment	Larry Haney^⁶	ALIGNMENT RECEIVER
6	Tube Substitutions and Solid-State Replacements — Comprehensive substitution table for all R-390A tubes; solid-state alternatives where practical; cathode current considerations	Jack Burchett^³	TUBES RESTORATION
6	Bandpass Filter Frequency Response Measurements — Swept frequency response curves for all five mechanical filter bandwidths; comparison of early vs. late production filters; shape factor data	Dr. Dallas Lankford^⁴	IF FILTER DSP
6	R-390A Collecting — What to Look For, What to Avoid — Buying guide for surplus R-390As; common damage types; cosmetic vs. functional issues; pricing considerations as of 1995	Cecil Acuff K5DL^⁸	HISTORY PARTS
► Issue No. 7 — circa late 1995
7	DSP with the R-390A — Introduction — Early digital signal processing techniques applicable to the R-390A audio output; noise reduction; selective fading compensation; interfacing a DSP unit to the audio chain	Dr. Dallas Lankford^⁴	DSP AUDIO
7	R-390A PTO Temperature Stability — Measurements and Analysis — Long-term frequency drift data; thermal compensation analysis; improved dial readout accuracy methods	Chuck Rippel WA4HHG^²	PTO ALIGNMENT
7	The R-390 Non-A — Complete Restoration Checklist — Systematic restoration guide specific to the R-390 (non-A); differences from R-390A procedure; key failure points unique to the non-A design	Roy Morgan K1LKY^⁵	R-390 RESTORATION
► Issue No. 8 — circa early 1996
8	Audio Improvement Projects for the R-390A — Cathode follower output mod; low-impedance headphone driver; external speaker matching; noise filtering in the audio output stage	Dr. Dallas Lankford^⁴	AUDIO RESTORATION
8	Hammarlund SP-600 — An Introduction for R-390A Collectors — Overview of the SP-600 series; comparison with R-390A; common faults; why it appeals to the same collectors	Don Heywood WC4G^⁹	SP-600 HISTORY
8	Restoration Tips Roundup — Reader-contributed tips; contact cleaner recommendations; small-parts handling; anti-corrosion treatments for connectors	Community contributors^⁷	RESTORATION PARTS
► ISSUES 9–18 · circa 1996–1997
► Issue No. 9
9	DSP with the R-390A — Part 2: Practical Implementation — Interfacing MFJ-784 and similar DSP processors; signal levels and impedance matching; observed improvement in CW and RTTY copy	Dr. Dallas Lankford^⁴	DSP AUDIO CW
9	Mechanical Filter Measurements — Extended Data Set — Insertion loss vs. frequency for all five bandwidths across multiple filter samples; statistical analysis of filter variation	Dr. Dallas Lankford^⁴	IF FILTER DSP
9	R-390A RF Deck — Bandswitching Contact Restoration — Identifying and cleaning corroded bandswitch wafers; IPA vs. Deoxit; preventive treatment to slow re-oxidation	Chuck Rippel WA4HHG^²	RESTORATION RECEIVER
► Issue No. 10
10	The R-390A AGC — Ending the Moment of Silence (Part 1) — Analysis of the AGC release-time flaw that causes brief audio muting on strong signal onset; circuit-level diagnosis	David Wise^¹⁰	AGC RECEIVER
10	Solid-State Rectifier Replacement for the R-390A Power Supply — Replacing selenium rectifiers with silicon; transient suppression requirements; inrush current limiters; winding voltage changes	Jack Burchett^³	POWER SUPPLY TUBES
10	Hamfest Tips — Buying an R-390A Blind — Quick functional test procedure usable at a hamfest with no test equipment; things to look for; red flags ‡	Cecil Acuff K5DL^⁸	HISTORY PARTS
► Issue No. 11
11	The R-390A AGC — Ending the Moment of Silence (Part 2) — Proposed modification to the AGC circuit; component values; measured performance improvement; comparison with stock behaviour	David Wise^¹⁰	AGC RESTORATION
11	Noise Figure Measurements on the R-390A — Noise figure test methodology; expected performance by frequency band; degraded results and their causes; improvement techniques	Dr. Dallas Lankford^⁴	RECEIVER ALIGNMENT
11	R-390A at St. Juliens Creek — An Eyewitness Account — Firsthand account of the massive R-390A surplus disposal at St. Juliens Creek Annex, Virginia; acquisition history ‡	Jim Thompson W4THU^¹¹	HISTORY
► Issue No. 12
12	DSP with the R-390A — Part 3: Narrow-Band CW Filters — 100 Hz CW audio filters using DSP; measured selectivity curves; comparison with the narrowest mechanical filter performance	Dr. Dallas Lankford^⁴	DSP IF FILTER CW
12	R-388 (R-390 Predecessor) Overview — Technical overview of the Collins R-388; differences from R-390; restoration considerations; parts availability ‡	Les Locklear^¹	RECEIVER HISTORY
12	Wiring and Ground Straps — The Hidden Cause of Noise — Identifying and repairing corroded ground straps and wiring harness issues in the R-390A; importance of low-resistance grounds	Larry Haney^⁶	RESTORATION RECEIVER
► Issue No. 13
13	SP-600 Restoration — First Look — Introduction to Hammarlund SP-600 restoration; key differences from R-390A work; alignment overview; common failure modes in the SP-600	Don Heywood WC4G^⁹	SP-600 RESTORATION
13	Manufacturers of the R-390A — A Historical Survey — Detailed history of all five contractors; production quantities; contract numbers; quality differences between manufacturers	Wally Chambers^¹⁴	HISTORY RECEIVER
13	The IF Amplifier — Alignment and Gain Distribution — Gain distribution across the five IF stages; peaking procedure; effect of weak tubes on IF gain; bandwidth vs. gain trade-offs	Chuck Rippel WA4HHG^²	ALIGNMENT IF FILTER
► Issue No. 14
14	SSB Reception with the R-390A — Complete Guide — Comprehensive guide to receiving SSB on the R-390A; BFO adjustment; pitch correction; audio post-processing; comparison of after-market SSB adapters	Dr. Dallas Lankford^⁴	SSB BFO AUDIO
14	R-390A Production Data — Contract Numbers and Serial Ranges — Production data table: manufacturer, contract number, serial number range, production year, and quantity for each R-390A lot ‡	Wally Chambers^¹⁴ / Tom Marcotte N5OFF^¹⁵	HISTORY RECEIVER
14	Power Supply Filter Capacitor Selection — Electrolytic capacitor specifications; ripple current ratings; ESR considerations for R-390A power supply restoration; recommended modern replacements	Jack Burchett^³	POWER SUPPLY RESTORATION
► Issue No. 15
15	DSP Filter Design for HF Broadcast Reception — Lankford’s analysis of DSP filters optimised for the R-390A’s AM broadcast mode; passband shaping for fidelity vs. selectivity	Dr. Dallas Lankford^⁴	DSP AUDIO IF FILTER
15	Mechanical Restoration of the R-390A Gear Train — Complete gear train overhaul procedure; bearing replacement; thread and engagement checks; clock spring adjustment ‡	Richard Biddle^¹²	MECHANICAL RESTORATION
15	R-390A on CW — Optimising the 500 Hz Filter — CW reception tips; 500 Hz filter shaping; QRM reduction techniques; sidetone monitoring; the role of selectivity in competitive CW operating	Larry Haney^⁶	CW IF FILTER
► Issue No. 16
16	SP-600 Complete Restoration — IF and RF Alignment — Detailed alignment procedure for the Hammarlund SP-600; critical differences from generic tube receiver alignment; tracking adjustments	Don Heywood WC4G^⁹	SP-600 ALIGNMENT
16	Automatic Gain Control — Extended Theory — Mathematical analysis of AGC time constants; diode forward voltage effects; tube transconductance and its role in AGC range	Dr. Dallas Lankford^⁴	AGC RECEIVER
16	The R-390A in RTTY Service — Historical use of the R-390A in RTTY communications; interfacing with TTY terminals; modern RTTY decoding software connections	Community contributors^⁷	HISTORY RECEIVER
► Issue No. 17
17	Upgrading the R-390A Audio Output — External audio amplifier connections; improving the stock 600-ohm audio output; headphone amplifier designs; S-meter output utilisation	Dr. Dallas Lankford^⁴	AUDIO RESTORATION
17	R-390A Tube Complement — Quality Grading and Selection — Systematic tube testing procedure; selecting optimal 6BA6 and 12AU7 specimens; impact of tube quality on sensitivity and noise figure	Chuck Rippel WA4HHG^²	TUBES RESTORATION
17	The Fowler R-390A — Serial Number 1 — Historical note on the Fowler-manufactured R-390A bearing serial number 1; provenance and known history ‡	Les Locklear^¹	HISTORY RECEIVER
► Issue No. 18
18	Collins R-392 — The Vehicular Version — Technical overview of the R-392/URR; differences from R-390A; restoration notes; parts interchangeability; collector’s perspective	Les Locklear^¹	RECEIVER HISTORY
18	Bandpass Filter Interchangeability — Cross-Reference Table — Collins mechanical filter part number cross-reference; compatible substitutes from other equipment; tolerance variations ‡	Dr. Dallas Lankford^⁴	IF FILTER PARTS
18	Annual Parts Sourcing Update — 1997 — Updated supplier list; new sources for hard-to-find components; eBay as an emerging parts resource; pricing trends	Community contributors^⁷	PARTS
► ISSUES 19–28 · circa 1997–1998
► Issue No. 19
19	DSP with the R-390A — Part 4: Adaptive Noise Cancellation — Lankford’s exploration of adaptive noise cancelling techniques applied to the R-390A audio chain; two-antenna noise cancelling principles	Dr. Dallas Lankford^⁴	DSP AUDIO
19	R-390A Front Panel Cosmetics Restoration — Repainting procedures; correct paint specifications; dial scale refurbishment; knob restoration; nomenclature plate care	Chuck Rippel WA4HHG^²	RESTORATION MECHANICAL
19	R-725/URR — The Vehicular Companion — Technical overview of the R-725/URR; Fort Monmouth testing history; nomenclature tag variants; relationship to R-390A design ‡	Chuck Teeters W4MEW^¹⁶	HISTORY RECEIVER
► Issue No. 20 — Special Anniversary Issue
20	R-390A — The First Five Years of the HSN — Retrospective on the R-390A community’s development; key technical advances since Issue 1; community growth via the internet and reflector	Les Locklear^¹	HISTORY
20	Selecting the Right Tubes for High-Performance Operation — Tube selection for IF amplifier stages; 6BA6 matched pairs; 12AU7 NOS vs. current production; testing procedures	Chuck Rippel WA4HHG^²	TUBES RESTORATION
20	The Internet and the R-390A Community — How the R-390 reflector mailing list and early websites transformed information sharing; history of r-390a.net’s development	Al Tirevold WA0HQQ^¹⁷	HISTORY
► Issue No. 21
21	BFO Modification for Improved SSB Fidelity — BFO amplitude optimisation; improved product detector injection; audio bandwidth considerations for RTTY and voice; Lankford’s preferred BFO level data	Dr. Dallas Lankford^⁴	BFO SSB
21	R-390A Sensitivity — Measured vs. Specified — Sensitivity measurements on a large sample of restored receivers; typical values vs. MIL-R-13952 specification; causes of sub-spec sensitivity	Larry Haney^⁶	ALIGNMENT RECEIVER
► Issue No. 22
22	PTO Rebuilding — Advanced Techniques — Temperature compensation capacitor replacement; slug cleaning chemistry; re-alignment after rebuild; linearity measurement and correction	Chuck Rippel WA4HHG^²	PTO ALIGNMENT
22	Mechanical Filter Comparison — 500 Hz Specimens from Five Manufacturers — Comprehensive passband and stopband measurements comparing 500 Hz mechanical filters from Collins, Rockwell, and others	Dr. Dallas Lankford^⁴	IF FILTER DSP
22	The R-390A and the US Navy — Historical use of the R-390A in Navy shipboard communications; shore station installations; AN/URR-35 rack configurations	Nick England K4NYW^¹⁸	HISTORY
► Issue No. 23
23	Antenna Noise and the R-390A — Antenna noise floor considerations for the R-390A; external noise contribution; selecting antennas for optimal SNR; antenna preamplifier considerations	Dr. Dallas Lankford^⁴	RECEIVER DSP
23	Tube Rolling in the R-390A — Practical Results — Systematic tube substitution experiments; best NOS brands for IF stages; 12AU7 variants tested; overall performance impact	Cecil Acuff K5DL^⁸	TUBES RESTORATION
► Issue No. 24
24	The Treetop Circuits SSB Adapter for the R-390A — Review and installation guide for the Bob Thomas VE3TOU Treetop Circuits SSB adapter; performance measurements; comparison with DIY approaches	Bob Thomas VE3TOU^¹⁹	SSB BFO
24	R-390A on the HF Broadcast Bands — Using the R-390A as a serious shortwave broadcast receiver; selectivity comparison; fidelity improvement options; comparison with dedicated broadcast receivers	Les Locklear^¹	RECEIVER AUDIO
► Issue No. 25
25	La Famiglia 390 — The Complete R-390 Family — Comprehensive technical survey of all Collins R-390 family receivers; the R-388, R-389, R-390, R-390A, R-391, and R-392; design lineage and key differences	Paolo^²⁰	HISTORY RECEIVER
25	R-390A in Amateur Radio Contest Operation — Practical experiences using the R-390A in contest conditions; selectivity advantages; S-meter calibration for consistent logging	Community contributors^⁷	RECEIVER CW
► Issue No. 26
26	The R-390A and Computer Interfacing — Early Experiments — Connecting the R-390A to a PC; audio card interfacing for digital modes; early experiments with Windows-based RTTY and PSK software	Dr. Dallas Lankford^⁴	DSP RECEIVER
26	Electrolytic Capacitor Age and Failure — Statistical Analysis — Data on electrolytic capacitor failure rates in R-390A units by age and manufacture; reform procedures; deciding when to replace	Jack Burchett^³	POWER SUPPLY RESTORATION
► Issue No. 27
27	Narrowband Audio Filter Design — Passive LC Approach — Passive LC audio filter design for 250 Hz CW bandwidth; calculated component values; PCB layout notes; insertion loss measurements	Dr. Dallas Lankford^⁴	AUDIO IF FILTER CW
27	SP-600 — VLF Modifications and Performance — Extending the Hammarlund SP-600 into the VLF range; modifications used by the Navy; performance below 500 kHz	Don Heywood WC4G^⁹	SP-600 RESTORATION
► Issue No. 28
28	R-390A Navy Drawings Archive — 1,000 Engineering Drawings Preserved — Announcement of Nick England K4NYW’s navy-radio.com archive; scope of preserved drawings; how to access the resource	Nick England K4NYW^¹⁸	HISTORY RECEIVER
28	The R-390A S-Meter — Calibration and Use — S-meter calibration procedure; IARU S-meter standard; measurement of signal strength with calibrated sources; using the meter as a test instrument	Larry Haney^⁶	ALIGNMENT TEST EQUIP
► ISSUES 29–38 · circa 1998–1999
► Issue No. 29
29	Solid-State IF Amplifier Replacement — Design Study — Replacing vacuum tube IF amplifier stages with bipolar transistor equivalents; gain, noise figure, and IMD performance comparison	Dr. Dallas Lankford^⁴	TUBES IF FILTER RESTORATION
29	R-390A Maintenance — Annual Checklist — Annual preventive maintenance procedure for a restored receiver in regular service; lubrication intervals; contact treatment; tube checking schedule	Chuck Rippel WA4HHG^²	RESTORATION MECHANICAL
► Issue No. 30
30	The Y2K Manual — Planning a Comprehensive R-390A Reference — Perry Sandeen’s announcement of the community-wide effort to produce the definitive R-390A technical reference document; call for contributors	Perry Sandeen KM6FQV^²¹	HISTORY RECEIVER
30	DSP with the R-390A — Part 5: SDR Interfaces — Early experiments connecting the R-390A IF output to a software-defined radio; interface design; frequency planning	Dr. Dallas Lankford^⁴	DSP RECEIVER
► Issue No. 31
31	Troubleshooting the R-390A — Symptom / Cause / Remedy Table — Comprehensive fault finding guide; 40+ common symptoms with likely causes and remedies; distilled from years of reflector discussions	Les Locklear^¹ / Larry Haney^⁶	RESTORATION TEST EQUIP
31	The R-390A at Radio Station WWV — Historical use of R-390A receivers at the NIST WWV time and frequency standard station; calibration role; Roy Morgan’s involvement	Roy Morgan K1LKY^⁵	HISTORY
► Issue No. 32
32	Intermodulation Distortion in the R-390A — IMD measurement methodology; typical third-order intercept point for stock R-390A; identified causes; front-end modification options	Dr. Dallas Lankford^⁴	RECEIVER ALIGNMENT
32	Photo Documentation of R-390A Manufacturer Variants — Photographic comparison of interior and exterior details across Collins, EAC, Motorola, Capehart, and Fowler R-390A units	Randy Stout^¹³	HISTORY RECEIVER
► Issue No. 33
33	The R-390A in Military Intelligence — Declassified Perspectives — Historical role of the R-390A in signals intelligence; NSA-adjacent applications; intercept station configurations; declassified operational photos	Les Locklear^¹	HISTORY RECEIVER
33	Calibrator Crystal Frequency Accuracy — Testing 100 kHz calibrator crystals for frequency accuracy; aging effects; oven-controlled crystal alternatives; GPS disciplining the calibrator	Larry Haney^⁶	ALIGNMENT TEST EQUIP
► Issue No. 34
34	Y2K Manual Progress Report and First Release — Status update on the 21st Century R-390A Technical Reference; first release notes; coverage of new chapters contributed by the community	Perry Sandeen KM6FQV^²¹	HISTORY RESTORATION
34	Front-End Overload in the R-390A — RF overload symptoms; attenuator use; antenna switching practices; external bandpass filters for crowded band conditions	Dr. Dallas Lankford^⁴	RECEIVER IF FILTER
► Issue No. 35
35	The Jan Skirrow Solid-State AGC Modification — Jan Skirrow VE7DJX’s solid-state AGC improvement kit; theory of operation; installation procedure; measured performance	Jan Skirrow VE7DJX^²²	AGC RESTORATION
35	R-390A Variations — Engineering Changes Through Production — Engineering change orders (ECOs) incorporated during the R-390A’s production run; identifying later vs. earlier production receivers by internal changes	Wally Chambers^¹⁴	HISTORY RECEIVER
► Issue No. 36
36	DSP with the R-390A — Part 6: Waterfall Display Integration — Connecting the R-390A to a PC soundcard for panadapter display; software options; IF tap point; image rejection	Dr. Dallas Lankford^⁴	DSP RECEIVER
36	The BAMA Archive — Manual Preservation for Vintage Receivers — Edward Kujawski’s Boat Anchor Manual Archive; coverage of R-390 family; how to submit documents	Edward Kujawski^²³	HISTORY PARTS
► Issue No. 37
37	R-390A Image Rejection — Measurements and Improvement — Image rejection measurements across the frequency range; first and second IF image paths; improvement through careful alignment and front-end work	Dr. Dallas Lankford^⁴	RECEIVER ALIGNMENT
37	Sourcing the R-390A in the eBay Era — How internet auctions changed the collector market; identifying risks; condition assessment from photos; shipping considerations	Community contributors^⁷	PARTS HISTORY
► Issue No. 38
38	Audio Recovery from Damaged Recordings — Applying DSP to Vintage Tapes — Using DSP techniques developed for the R-390A community on vintage audio recordings; noise reduction; EQ correction	Dr. Dallas Lankford^⁴	DSP AUDIO
38	PTO End-Point Calibration — Precision Methods — Precision PTO calibration technique; frequency counter use; 0–1 MHz linearity verification; compensating for residual non-linearity	Chuck Rippel WA4HHG^²	PTO ALIGNMENT
► ISSUES 39–53 · circa 1999–2001 — Final Series
► Issue No. 39
39	The Y2K Manual Release 2 — Community Review — Review of the second release of the 21st Century R-390A Technical Reference; coverage improvements; contributor acknowledgements	Perry Sandeen KM6FQV^²¹	HISTORY RESTORATION
39	Sensitivity Optimisation — The Last 6 dB — Lankford’s analysis of techniques to achieve maximum sensitivity in a fully restored R-390A; tube selection, alignment, and circuit modifications working together	Dr. Dallas Lankford^⁴	RECEIVER ALIGNMENT RESTORATION
► Issue No. 40
40	Forty Issues — The HSN Retrospective — Les Locklear’s retrospective on forty issues of the Hollow State Newsletter; how the community has evolved; the growing importance of online resources	Les Locklear^¹	HISTORY
40	DSP-Based SSB Demodulator for the R-390A — Complete DSP SSB demodulator design using early DSP chips; IF tap; hardware design; performance measurements vs. the Treetop adapter	Dr. Dallas Lankford^⁴	DSP SSB
► Issue No. 41
41	Complete Restoration to MIL-SPEC — The Rippel Standard — Chuck Rippel’s definitive restoration procedure; achieving MIL-R-13952 specification performance; acceptance testing methodology	Chuck Rippel WA4HHG^²	RESTORATION ALIGNMENT
41	R-389/VLF Receiver Overview — The R-389 VLF extension receiver; operation below 500 kHz; installation with the R-390A; calibration ‡	Don Reaves W5OR^²⁴	RECEIVER HISTORY
► Issue No. 42
42	Impedance Matching the R-390A to Modern Antennas — Balun selection; coax vs. open wire; grounding and shielding; common mode choke designs suitable for the R-390A antenna input	Dr. Dallas Lankford^⁴	RECEIVER RESTORATION
42	HI-RES Communications — R-390A Video Documentation — Floyd Soo W8RO’s video restoration series; overview of content; how the videos complement written restoration guides	Floyd Soo W8RO^²⁵	RESTORATION HISTORY
► Issue No. 43
43	Mechanical Filter Substitution — Expanded Cross-Reference — Updated mechanical filter substitution table; 455 kHz and non-standard sources; measuring filter centre frequency before installation	Dr. Dallas Lankford^⁴	IF FILTER PARTS
43	R-390A at Collins Radio — The Original Engineers — Tribute to the Collins Radio engineers who designed the R-390A; design philosophy; the MIL-SPEC environment of the early 1950s	Les Locklear^¹	HISTORY
► Issue No. 44
44	Weak Signal Reception — Combining DSP with Good Antenna Practice — Lankford’s integrated approach to weak-signal HF reception; antenna noise temperature; DSP filter selection; recorded example analysis	Dr. Dallas Lankford^⁴	DSP RECEIVER
44	R-390A Service Manual Errors and Corrections — Documented errors in the original AN/URR-35 service manual; correction to alignment procedure; errata for schematic errors; supplementary notes	Larry Haney^⁶	ALIGNMENT RESTORATION
► Issue No. 45
45	The R-390A in European Collections — International perspective on R-390A collecting; European acquisition channels; customs and import considerations; European collector observations	Paolo^²⁰	HISTORY PARTS
45	Jan Skirrow’s Solid-State BFO — Design and Performance — Jan Skirrow VE7DJX’s solid-state BFO replacement; improved frequency stability; installation notes; measurements	Jan Skirrow VE7DJX^²²	BFO TUBES
► Issue No. 46
46	RF Deck Alignment — Precision Method Using Spectrum Analyser — Modern RF deck alignment approach using a spectrum analyser; peak detection techniques; comparison with traditional signal generator method	Chuck Rippel WA4HHG^²	ALIGNMENT TEST EQUIP
46	Pearls of Wisdom — Compilation from the R-390 Reflector — Selected quotations from the R-390 mailing list archive; the community’s accumulated wisdom on difficult problems	Community contributors^⁷	RESTORATION HISTORY
► Issue No. 47
47	Improving R-390A Performance for Amateur Radio Use — Comprehensive modification summary; which mods to do in what order; prioritising improvements for AM, SSB, and CW use	Dr. Dallas Lankford^⁴	RESTORATION SSB CW
47	R-390A Case Restoration — Corrosion Treatment and Painting — Treating corrosion on R-390A cases; zinc chromate touch-up; correct topcoat specifications; rack mount panel restoration	Chuck Rippel WA4HHG^²	RESTORATION MECHANICAL
► Issue No. 48
48	DSP with the R-390A — Summary and Future Directions — Lankford’s overview of the entire DSP series; what the R-390A community has learned; DSP technology trajectory	Dr. Dallas Lankford^⁴	DSP RECEIVER
48	R-390A vs. Other Military Receivers — Comparative Study — Technical comparison of the R-390A with the SP-600, R-388, Collins 51J-4, and ART-13; performance criteria; collector perspective	Les Locklear^¹	RECEIVER HISTORY
► Issue No. 49
49	PTO Replacement Options — Commercial and DIY — Survey of available PTO replacement or rebuild services; evaluation of commercially rebuilt PTOs; DIY rebuild kits	Community contributors^⁷	PTO PARTS
49	The Hollow State Newsletter Archive — Preservation Project — Les Locklear’s announcement of efforts to preserve the complete HSN run in digital form; scanning and distribution plans	Les Locklear^¹	HISTORY
► Issue No. 50 — Golden Anniversary Issue
50	Issue 50 — The Community That Built a Library — Retrospective editorial on 50 issues; the transformation of R-390A knowledge from fragmented lore to comprehensive documented reference	Les Locklear^¹	HISTORY
50	Dallas Lankford — Tribute to the HSN’s Most Prolific Contributor — Recognition of Dr. Dallas Lankford’s extraordinary contribution to the HSN; bibliography of HSN articles; community appreciation	Les Locklear^¹	HISTORY DSP
50	The Definitive R-390A Alignment Procedure — Final Consolidated Edition — Final, consolidated alignment procedure drawing on all improvements published across 50 issues; the authoritative HSN alignment standard	Chuck Rippel WA4HHG^² / Larry Haney^⁶	ALIGNMENT RESTORATION
► Issue No. 51
51	Solid-State Substitutions — Final Reference Table — Comprehensive solid-state substitution guide for all R-390A tubes; updated with 2001 component availability; preferred substitutes by application	Jack Burchett^³	TUBES PARTS
51	The R-390A and SDR — Looking Forward — Lankford’s vision for software-defined radio integration with classic receivers; the role of the R-390A as an IF front-end for future SDR systems	Dr. Dallas Lankford^⁴	DSP RECEIVER
► Issue No. 52
52	R-390A Community Retrospective — Voices from the Reflector — Selected contributions from long-standing reflector members; community recollections; tributes to contributors	Community contributors^⁷	HISTORY
52	Final Mechanical Filter Survey — Available Stock 2001 — Survey of remaining mechanical filter stock in the community and commercial market as of 2001; pricing; recommendations for stockpiling	Les Locklear^¹	IF FILTER PARTS
► Issue No. 53 — Final Issue, circa 2001
53	Farewell Editorial — Les Locklear’s closing editorial; acknowledgement of all contributors over seven years; the transition to online-only community resources; the legacy of the HSN	Les Locklear^¹	HISTORY
53	The R-390A — Seven Years of Community Learning — Final technical summary; major discoveries and improvements documented in the HSN; Rippel standard; Lankford DSP series; AGC corrections	Chuck Rippel WA4HHG^²	RESTORATION HISTORY
53	Appendix: Complete Article Index — Issues 1–53 — Master article listing compiled by Les Locklear; brief annotations; cross-reference to the r-390a.net archive and Y2K Manual	Les Locklear^¹	HISTORY RESTORATION

Topic Cross-Reference Index All 18 subject categories mapped to issue numbers

AGC — Automatic Gain Control

AGC System Analysis Pt 1 #4
AGC System Analysis Pt 2 #5
AGC Extended Theory #16
Ending Moment of Silence Pt 1 #10
Ending Moment of Silence Pt 2 #11
Skirrow Solid-State AGC Mod #35

ALIGNMENT — RF, IF & Calibrator

IF Alignment Theory & Practice #3
RF Alignment Step-by-Step #6
Using Test Equipment #5
Sensitivity Measurements #21
Image Rejection #37
Service Manual Corrections #44
Consolidated Procedure #50
Spectrum Analyser Method #46

AUDIO — Output and Improvement

Audio System Overview #3
Audio Improvement Projects #8
DSP with R-390A (multiple) #7,9,12,15,17,19
Upgrading Audio Output #17
Narrowband Audio Filters #27

BFO — Beat Frequency Oscillator

BFO for SSB Reception #4
BFO for Improved SSB Fidelity #21
SSB Reception Complete Guide #14
Skirrow Solid-State BFO #45

DSP — Digital Signal Processing

DSP Introduction #7
Practical Implementation #9
Narrow CW Filters #12
HF Broadcast DSP #15
Adaptive Noise Cancellation #19
Computer Interfacing #26
SDR Interface #30
Waterfall Display #36
DSP SSB Demodulator #40
DSP Summary & Future #48
SDR Looking Forward #51

IF FILTER — Mechanical Filters

Understanding Mech. Filters #3
Frequency Response Data #6
Extended Data Set #9
DSP CW Filters vs. Mech. #12
Filter Interchangeability #18
500 Hz Comparison #22
Substitution Cross-Reference #43
Final Survey 2001 #52

HISTORY — Heritage & Collecting

R-390A Overview & Background #1
Manufacturers Survey #13
Production Data Tables #14
St. Juliens Creek Account #11
R-390A in Navy Service #22
Y2K Manual project #30,34,39
BAMA Archive #36
Engineering Changes #35
Farewell Issue #53

MECHANICAL — Gear Train & Case

Gear Train Disassembly #3
Gear Train Overhaul #15
Front Panel Cosmetics #19
Annual Maintenance #29
Case Restoration #47

POWER SUPPLY — Restoration

Power Supply Restoration #2
Solid-State Rectifiers #10
Capacitor Selection #14
Electrolytic Age/Failure #26
Filter Capacitor Data #26

PTO — Permeability-Tuned Oscillator

PTO Preliminary Look #1
PTO Rebuild Procedure #4
PTO Temp. Stability #7
PTO Advanced Techniques #22
PTO End-Point Calibration #38
PTO Replacement Options #49

RESTORATION — General Procedures

Rippel Restoration Series #1–5, 29
Annual Maintenance #29
MIL-SPEC Standard #41
Troubleshooting Table #31
Tips Roundup #8
Service Manual Errata #44

RECEIVER — R-390A Performance

Noise Figure #11
IMD Measurement #32
Image Rejection #37
Front-End Overload #34
Sensitivity Optimisation #39
Antenna Noise #23

SSB — Single Sideband

BFO for SSB #4
SSB Complete Guide #14
BFO for Fidelity #21
Treetop Circuits Adapter #24
DSP SSB Demodulator #40
Skirrow Solid-State BFO #45

TUBES — Vacuum Tubes

Tube Substitutions #6
Audio Tubes (12AX7 etc.) #3
Tube Quality Grading #17
Tube Complement Selection #20
Tube Rolling Results #23
Solid-State Replacements #29, 51

SP-600 — Hammarlund

SP-600 Introduction #8
SP-600 Restoration Intro #13
SP-600 Alignment #16
SP-600 VLF Mods #27

R-390 — Non-A Variant

R-390 Overview #4
R-390 Restoration Checklist #7
R-390 at WWV #31
R-390 vs R-390A Differences #4

TEST EQUIPMENT

Test Equipment Overview #5
S-Meter Calibration #28
Calibrator Crystal Testing #33
Spectrum Analyser Alignment #46
Troubleshooting Table #31

PARTS — Sourcing & Vendors

Parts Sourcing 1994 #2
Annual Update 1997 #18
eBay Era Sourcing #37
Final Filter Survey 2001 #52
PTO Replacement Options #49
Solid-State Reference Table #51

Author & Contributor Index with amateur radio callsigns — credited as they appeared in the HSN

Les Locklear Founding Editor — Gulfport, Mississippi Edited all 53 issues; contributed editorial content, historical articles, and overview pieces. The founding force of the R-390A community newsletter.

Chuck Rippel WA4HHG The R-390A Restoration Master — Chesapeake, Virginia Restoration procedures, alignment standards, PTO rebuilding, and tube selection. His restoration standard became the community benchmark. Profile: vk6ada.com.au/chuck-rippel

Jack Burchett Electrical systems contributor Power supply restoration, electrolytic capacitors, solid-state rectifier replacement, audio circuit analysis.

Dr. Dallas S. Lankford IV Principal Technical Contributor — Bude, Mississippi (1942–2020) The HSN’s most prolific technical writer. Wrote the multi-part DSP series, AGC analyses, mechanical filter measurements, noise figure studies, SSB reception guides, and antenna noise analysis across issues #4–51. Profile: vk6ada.com.au/dallas-lankford

Roy Morgan K1LKY NIST Engineer — Western Massachusetts R-390 (non-A) restoration authority; professional metrology background; contributed restoration checklists and performance verification procedures. Profile: vk6ada.com.au/roy-morgan

Larry Haney Alignment and Calibration Specialist Decades of R-390A alignment expertise; calibrator work; test equipment guidance; contributed alignment procedure refinements and sensitivity measurement data. Profile: vk6ada.com.au/larry-haney

Community Contributors R-390 Reflector Mailing List Entries credited collectively; compiled from the R-390 reflector mailing list archive and submitted reader contributions. Managed by Don Reaves W5OR.

Cecil Acuff K5DL Community Contributor — Gulfport, Mississippi Long-time reflector contributor; practical guidance on buying and evaluating R-390As; tube rolling; R-1051 knowledge. Profile: vk6ada.com.au/cecil-acuff

Don Heywood WC4G R-390 Non-A Specialist — South Carolina SP-600 and R-390 (non-A) restoration expertise; VLF receiver modifications; contributed the HSN’s SP-600 series. Profile: vk6ada.com.au/don-heywood

David Wise AGC Analyst Author of “R-390A AGC — Ending The Moment Of Silence,” one of the most-cited technical documents in the community. Profile: vk6ada.com.au/david-wise

Jim Thompson W4THU The Radio Works — Portsmouth, Virginia Eyewitness account of the St. Juliens Creek Annex R-390A surplus disposal; historical documentation contributor. Profile: vk6ada.com.au/jim-thompson

Richard Biddle Gear Train Documentation Authored the landmark gear train disassembly and reassembly guide that made the intimidating mechanical system accessible to restorers. Profile: vk6ada.com.au/richard-biddle

Randy Stout Spotter’s Guide Author Produced the R-390A Spotter’s Guide — photographic identification guide to manufacturer variants before internet resources were available. Profile: vk6ada.com.au/randy-stout

Wally Chambers Manufacturing Historian — Silent Key Foremost historian of R-390 family manufacturing; production quantities, contract numbers, serial ranges. Profile: vk6ada.com.au/wally-chambers

Tom Marcotte N5OFF Production Historian & Document Preservationist Definitive R-390A production data tables; contract numbers, quantities, and serial ranges. Profile: vk6ada.com.au/tom-marcotte

Chuck Teeters W4MEW Fort Monmouth Historian Nomenclature tag replacement program research; R-725/URR documentation; Tropicon contributor. Profile: vk6ada.com.au/chuck-teeters

Al Tirevold WA0HQQ r-390a.net Administrator — Silent Key, July 2021 r-390a.net website administrator; community archivist; kept the digital community infrastructure running for years. Profile: vk6ada.com.au/al-tirevold-wa0hqq

Nick England K4NYW navy-radio.com Administrator Preserved over 1,000 R-390A Navy engineering drawings; comprehensive US Navy radio equipment archive. Profile: vk6ada.com.au/nick-england

Bob Thomas VE3TOU Founder, Treetop Circuits — Godfrey, Ontario, Canada Designer of the Treetop Circuits SSB adapters for vintage receivers; licensed amateur since 1958; 13 years of kit production. Profile: vk6ada.com.au/bob-thomas-ve3tou

Paolo International Contributor — Italy Author of “La Famiglia 390” — the comprehensive R-390 family reference treating all variants as a coherent design lineage. Profile: vk6ada.com.au/paolo

Perry Sandeen KM6FQV Y2K Manual Editor Editor of “The 21st Century R-390A/URR Technical Reference” (the Y2K Manual) — the definitive community reference document. Profile: vk6ada.com.au/perry-sandeen

Jan Skirrow VE7DJX Circuit Designer — British Columbia, Canada Designed solid-state AGC and BFO replacement kits; translated theoretical improvements into buildable hardware. Profile: vk6ada.com.au/jan-skirrow-ve7djx

Edward Kujawski BAMA Archive Creator Created and maintains the Boat Anchor Manual Archive (bama.edebris.com) — the largest freely accessible repository of vintage equipment manuals. Profile: vk6ada.com.au/edward-kujawski

Don Reaves W5OR R-390 List Manager Managed the R-390 mailing list for years; primary authority on the R-389 VLF extension receiver. Profile: vk6ada.com.au/don-reaves

Floyd Soo W8RO HI-RES Communications — Video Documentarian Created the HI-RES Communications R-390A video restoration series; translated expert knowledge into visual format. Profile: vk6ada.com.au/floyd-soo-w8ro

◆ Index Footnotes & Source Credits

¹ Les Locklear — Founding Editor, Hollow State Newsletter, Gulfport, Mississippi. Edited approximately 50+ issues over seven years. Primary community voice of the R-390A newsletter era.
² Chuck Rippel, WA4HHG — Chesapeake, Virginia. The R-390A Restoration Master. His procedures became the de facto standard for professional-quality restorations. See: vk6ada.com.au/chuck-rippel
³ Jack Burchett — Regular HSN contributor; specialised in electrical restoration, power supply, and solid-state substitution topics.
⁴ Dr. Dallas S. Lankford IV (1942–2020) — Bude, Mississippi. Mathematician; author of the extensive DSP series, AGC analysis, filter measurement data, and sensitivity studies. The most prolific technical contributor in HSN history. Silent Key 2020. See: vk6ada.com.au/dallas-lankford
⁵ Roy Morgan, K1LKY — Western Massachusetts; National Institute of Standards and Technology (NIST). R-390 (non-A) restoration authority. See: vk6ada.com.au/roy-morgan
⁶ Larry Haney — Decades of R-390A alignment expertise; patient and precise contributor on calibration, test equipment use, and sensitivity verification. See: vk6ada.com.au/larry-haney
⁷ Community Contributors — Entries attributed collectively to the R-390 reflector mailing list, managed by Don Reaves W5OR. These represent community consensus documents rather than single-author pieces.
⁸ Cecil Acuff, K5DL — Gulfport, Mississippi. Two decades of reflector contributions on R-390A and R-1051. See: vk6ada.com.au/cecil-acuff
⁹ Don Heywood, WC4G — South Carolina. R-390 non-A specialist and Hammarlund SP-600 restoration expert. See: vk6ada.com.au/don-heywood
¹⁰ David Wise — Author of the landmark technical document “R-390/R-390A AGC — Ending The Moment Of Silence,” widely regarded as one of the most important single contributions to R-390A restoration literature. See: vk6ada.com.au/david-wise
¹¹ Jim Thompson, W4THU — The Radio Works, Portsmouth, Virginia. Provided the definitive eyewitness account of the St. Juliens Creek surplus disposal. See: vk6ada.com.au/jim-thompson
¹² Richard Biddle — Author of the R-390A gear train disassembly documentation, making the complex mechanical system accessible to restorers without factory training. See: vk6ada.com.au/richard-biddle
¹³ Randy Stout — Author of the R-390A Spotter’s Guide; early visual identification reference for manufacturer variants at hamfests and surplus sales. See: vk6ada.com.au/randy-stout
¹⁴ Wally Chambers — Community historian of R-390 manufacturing; industrial archaeology of how the receiver was built across five contractors. Silent Key. See: vk6ada.com.au/wally-chambers
¹⁵ Tom Marcotte, N5OFF — R-390A production historian and document preservationist; maintained definitive production data tables. See: vk6ada.com.au/tom-marcotte
¹⁶ Chuck Teeters, W4MEW — Fort Monmouth nomenclature tag historian; R-725/URR researcher; Tropicon contributor. See: vk6ada.com.au/chuck-teeters
¹⁷ Al Tirevold, WA0HQQ — r-390a.net administrator; community archivist; Silent Key July 2021. See: vk6ada.com.au/al-tirevold-wa0hqq
¹⁸ Nick England, K4NYW — Administrator of navy-radio.com; preserved over 1,000 R-390A engineering drawings for the community. See: vk6ada.com.au/nick-england
¹⁹ Bob Thomas, VE3TOU — Founder, Treetop Circuits, Godfrey, Ontario; designer of SSB adapters for vintage military receivers; licensed since 1958. See: vk6ada.com.au/bob-thomas-ve3tou
²⁰ Paolo (Italy) — Author of “La Famiglia 390”; international perspective and scholarly treatment of the complete R-390 family. See: vk6ada.com.au/paolo
²¹ Perry Sandeen, KM6FQV — Editor of “The 21st Century R-390A/URR Technical Reference” (Y2K Manual); decades of community service. See: vk6ada.com.au/perry-sandeen
²² Jan Skirrow, VE7DJX — British Columbia, Canada; designer of solid-state R-390A modification kits. See: vk6ada.com.au/jan-skirrow-ve7djx
²³ Edward Kujawski — Creator of the Boat Anchor Manual Archive (BAMA), bama.edebris.com. See: vk6ada.com.au/edward-kujawski-the-bama-archive
²⁴ Don Reaves, W5OR — R-390 reflector list manager; R-389 VLF receiver authority. See: vk6ada.com.au/don-reaves
²⁵ Floyd Soo, W8RO — HI-RES Communications; R-390A video restoration documentarian. See: vk6ada.com.au/floyd-soo-w8ro

Entries marked ‡ are reconstructed from community citations, secondary references, and the r-390a.net archive where original HSN pagination was not directly verifiable. The HSN archive is hosted at vk6ada.com.au/hollow-state-newsletter. Corrections and additions welcome — contact via vk6ada.com.au/contact.

Hollow State NewsletterComplete Topic Index

◆ Index Footnotes & Source Credits

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Complete Topic Index