vk6ada.com.au • Vintage Transceiver Comparison Series
Collins KWM-2A vs Yaesu FT-101E
Collins KWM-2A vs Yaesu FT-101E
Design, Performance, Maintainability and Active Restoration Services — A Complete Comparison
Two of the most celebrated HF transceivers of the valve era, compared across every dimension a collector and restorer needs to understand: design philosophy, frequency coverage, VFO architecture and stability, receiver dynamic range, transmit performance, ergonomics, restoration complexity, parts availability in 2026, and currently active restoration services for both. Two different engineering traditions, two different ideas of what a transceiver should be — and both still on the air.
✍ Mike Peace VK6ADA / r-390a.net Administrator
📅 March 2026
KWM-2A
FT-101E
⚙ All-tube Collins vs hybrid Yaesu • Design • Performance • Restoration • Services
The Collins KWM-2A and the Yaesu FT-101E occupy adjacent positions in the chronology of HF transceivers without being contemporaries in any meaningful design sense. The KWM-2A is the direct product of Collins Radio’s communications engineering tradition: conservative, all-tube, impeccably built, designed for a specific mission (sideband suppression and spectral purity at 100 watts) and executed with the materials and methods of the late 1950s through the 1960s. The FT-101E is the product of a different tradition entirely — Japanese pragmatic engineering of the early 1970s, hybrid in construction, comprehensive in band coverage, and designed to be the best transceiver available for the money in a market that Collins had largely stopped competing in by the time Yaesu arrived.
Collectors who own one often wonder about the other. Restorers who have worked on one find the other technically alien in important ways. This comparison provides the complete picture: where the two designs agree, where they fundamentally differ, which is easier to restore in 2026, and where to find professional restoration service for each today.
Section 1 — Design Philosophy: Two Different Ideas of a Transceiver
◆ Collins KWM-2A — The Communications Engineer’s Transceiver
Collins Radio designed the KWM-2 series as a professional-grade single sideband transceiver for both amateur and commercial communications service. Every design decision reflects the engineering priorities of the Collins communications division: transmit spectral purity above all, stability sufficient for long-distance SSB communications without a frequency standard, and durability for field and mobile service. The all-tube construction is not conservatism — it was the best available technology for achieving these goals when the KWM-2 was designed. The Collins mechanical filter at 455 kc is the centrepiece of both the transmit (carrier suppression, unwanted sideband rejection) and receive (selectivity) paths: the filter was Collins’s own innovation, and the KWM-2 was built around it.
The KWM-2A is not a “shack in a box” in the Yaesu sense. It is a transceiver element designed to be used as part of a station: paired with the 312B-4 speaker/console for monitoring, a Collins amplifier for extra power if needed, and operated by someone who understood the operating procedure. The metering, the mode selection, and the lack of many features that later transceivers considered standard are all consistent with a design intended for professional users rather than first-time operators.
The KWM-2A is not a “shack in a box” in the Yaesu sense. It is a transceiver element designed to be used as part of a station: paired with the 312B-4 speaker/console for monitoring, a Collins amplifier for extra power if needed, and operated by someone who understood the operating procedure. The metering, the mode selection, and the lack of many features that later transceivers considered standard are all consistent with a design intended for professional users rather than first-time operators.
◆ Yaesu FT-101E — The Amateur’s Complete Station
Yaesu designed the FT-101 series for a completely different customer: the licensed amateur operator who wanted a complete HF station in a single box, covering every HF amateur band from 160 metres to 10 metres, with modern ergonomics, a power meter, ALC, VOX, and a clarifier for working split-frequency DX. The hybrid construction — tube finals (2×6JS6C) with solid-state drivers, control circuits, and VFO — was the engineering pragmatism of the early 1970s: keep the tube finals because solid-state high-power HF amplifiers were not yet cost-effective, but use transistors everywhere they made the design cheaper, smaller, or more reliable.
The FT-101E does not aspire to Collins-grade transmit spectral purity. It aspires to cover all the bands, work conveniently, produce competitive power, and fit on an operator’s desk without requiring a companion unit. By those criteria it is a complete success, and its enormous commercial success confirms that those were exactly the right criteria for the 1970s amateur market. The fact that it is now collected and restored alongside the Collins equipment it was designed to replace is a testimony to the design’s durability.
The FT-101E does not aspire to Collins-grade transmit spectral purity. It aspires to cover all the bands, work conveniently, produce competitive power, and fit on an operator’s desk without requiring a companion unit. By those criteria it is a complete success, and its enormous commercial success confirms that those were exactly the right criteria for the 1970s amateur market. The fact that it is now collected and restored alongside the Collins equipment it was designed to replace is a testimony to the design’s durability.
Section 2 — Specifications at a Glance
Specification |
Collins KWM-2A |
Yaesu FT-101E |
Advantage |
|---|---|---|---|
| Production years | 1959–1980 (KWM-2 series) | 1974–1979 (approx.) | COLLINS Longer production / support life |
| Construction | All-tube; approximately 22 tubes | Hybrid; 2×6JS6C tube finals, solid-state drivers and VFO | CONTEXT Different design era; neither is inferior |
| Band coverage | 14–29.7 MHz standard; 3.5 and 7 MHz with plug-in band crystals | 1.8–29.7 MHz all HF amateur bands including 160 m | YAESU Complete HF coverage without crystal accessories |
| IF system | Single conversion; 455 kc; Collins mechanical filter | Double conversion; ~5.5 MHz first IF, 455 kc second IF; crystal lattice filter | COLLINS Mechanical filter superior passband shape and ultimate rejection |
| VFO type | Collins 70H-7 Permeability Tuned Oscillator (PTO) | LC permeability-tuned VFO, solid-state buffer | COLLINS PTO inherently more linear and stable; dial calibration outstanding |
| Tuning range (VFO) | 1 MHz per band segment; 10-turn readout dial | 1 MHz per band; analog dial + clarifier | COLLINS 10-turn vernier readout more precise in normal use |
| Output power (SSB PEP) | ~100 W PEP SSB; 2×6146B final | ~100–120 W PEP SSB; 2×6JS6C final | EQUAL Comparable on 20m; FT-101E slightly more on some bands |
| Modes | USB, LSB, CW, AM (CW with accessory filter) | USB, LSB, CW, AM, FM (some versions) | YAESU More mode options standard |
| Receiver sensitivity | <1 µV for 10 dB S/N (20 m) | <0.5 µV for 10 dB S/N (manufacturer stated) | EQUAL Both excellent; real-world performance depends on condition |
| AGC / ALC | Linear AGC; ALC from PA to speech processor | AGC with fast/slow selection; ALC feedback from PA | COLLINS Collins linear AGC more consistent; fewer ALC anomalies at high power |
| Weight | ~6.5 kg (14.3 lbs) | ~13 kg (28.5 lbs) | COLLINS KWM-2A significantly lighter for mobile/portable use |
| Dimensions (approx.) | 280×140×250 mm | 360×150×320 mm | COLLINS Significantly more compact |
| Companion units required | 312B-4 speaker/console (optional but standard); external keyer | Self-contained; built-in speaker optional | YAESU True stand-alone station without accessories |
| Power supply | Internal; 117/234 V AC mains | Internal; 100/117/220/240 V mains selectable | YAESU Multi-voltage; easier international use |
| Parts availability (2026) | Electronic parts excellent; mechanical items harder; 6146B readily available | 6JS6C final tubes SCARCE; solid-state components some obsolete | COLLINS All-tube design ages more gracefully from parts perspective |
| Collector value (2026) | High; premium for matching S-Line stations | Moderate to high; rising as FT-101 series appreciated | COLLINS Consistently higher market value; especially complete S-Line stations |
Section 3 — VFO Architecture and Frequency Coverage
The Collins PTO vs the Yaesu LC VFO
The most significant technical difference between the two transceivers for operating purposes is the VFO architecture. The Collins KWM-2A uses the same PTO (Permeability Tuned Oscillator) technology as the R-390A/URR and 75S-3 receivers — a precision mechanical device in which the inductance of a tuning coil is varied by the linear movement of a ferrite slug driven by a calibrated lead screw. The PTO’s mechanical dial calibration is essentially independent of temperature and aging because the frequency-determining elements are the physical geometry of the lead screw and the slug, not the drift-prone electrical components of a conventional LC oscillator.
The Yaesu FT-101E uses a conventional LC permeability-tuned VFO with a solid-state buffer amplifier. This is a good design that was well-executed by Yaesu, but it has an inherent limitation: the coil core material and the VFO circuit components change with temperature, causing frequency drift during the warm-up period that is absent (or negligibly small) in the Collins PTO design. The FT-101E’s VFO drift after 10–15 minutes of warm-up is typically within acceptable bounds, but the first minutes after switch-on can produce noticeable frequency shift that requires operator compensation.
The clarifier control. The FT-101E includes a “clarifier” control — a fine-tuning offset adjustment that allows the receive frequency to be trimmed independently of the transmit frequency. This is partly a practical response to the VFO’s warm-up drift: the clarifier allows the operator to compensate for small frequency offsets without moving the main tuning dial. The Collins KWM-2A has no equivalent because the PTO does not exhibit the warm-up drift that makes a clarifier useful. Whether the clarifier is a feature (convenient fine-tuning for DX work) or a workaround for a VFO limitation depends on how it is used.
Band Coverage: The Crystal Question
The KWM-2A’s limited standard coverage (14–29.7 MHz) reflects the amateur band priorities of the Collins era: 20m, 15m, and 10m were the primary DX bands, and the compact chassis left insufficient room for a comprehensive bandswitching arrangement. The 80m and 40m band capability required plug-in crystal accessories that many operators found inconvenient and some chose not to purchase. By contrast, the FT-101E’s 160m–10m coverage without any accessories reflects the 1970s operator’s expectation of a complete station: every licensed amateur band in one box, ready to go.
For a collector in 2026 primarily interested in 20m or 15m operation, the band coverage difference is irrelevant: the KWM-2A is fully adequate. For a collector who wants to operate on 80m, 40m, or 160m without sourcing and maintaining crystal accessories, the FT-101E’s coverage is a practical advantage that is hard to argue against.
Section 4 — Receive Performance
Collins KWM-2A Receive
The KWM-2A receive path benefits from the Collins mechanical filter’s outstanding passband shape factor. The mechanical filter’s rectangular passband — steep skirts and flat top — provides genuinely superior selectivity to the crystal lattice filters of the FT-101E, particularly for crowded band conditions where signals are within a few kilohertz of each other. The single conversion architecture avoids the image and spurious response issues that can affect double-conversion designs.
Dynamic range is good for an all-tube design but is ultimately limited by the receiver’s tube front end. On a modern 20m contest weekend with high signal densities, the KWM-2A may show more intermodulation distortion from close-spaced strong signals than a well-maintained FT-101E. The AGC system is linear and consistent, handling rapid signal level changes cleanly.
Audio quality is a consistent community compliment: the KWM-2A’s SSB audio has a natural, clear quality that many operators prefer to the audio of later transceivers, including the FT-101E. The receive audio stage is carefully designed and benefits from the mechanical filter’s well-defined selectivity.
Dynamic range is good for an all-tube design but is ultimately limited by the receiver’s tube front end. On a modern 20m contest weekend with high signal densities, the KWM-2A may show more intermodulation distortion from close-spaced strong signals than a well-maintained FT-101E. The AGC system is linear and consistent, handling rapid signal level changes cleanly.
Audio quality is a consistent community compliment: the KWM-2A’s SSB audio has a natural, clear quality that many operators prefer to the audio of later transceivers, including the FT-101E. The receive audio stage is carefully designed and benefits from the mechanical filter’s well-defined selectivity.
Yaesu FT-101E Receive
The FT-101E’s double-conversion receive path (first IF at approximately 5.5 MHz, second IF at 455 kc with crystal lattice filter) provides a sensible image rejection architecture that the KWM-2A’s single conversion system cannot match. On the higher HF bands (21 MHz and above), the double conversion provides cleaner rejection of images that would fall within audible range of the single-conversion KWM-2A’s IF.
The crystal lattice filter’s passband has less ideal shape factor than the Collins mechanical filter: the skirts are less steep and the passband has more ripple. In practice, on a quiet band, the difference between the two filters is small. Under contest conditions with multiple close-in strong signals, the Collins filter maintains cleaner audio. The FT-101E’s AGC has a fast/slow selection that the KWM-2A lacks, which some operators find useful for CW operation (fast AGC) vs SSB (slow AGC).
Receiver sensitivity is excellent in a correctly restored FT-101E, competitive with the KWM-2A on the same band. Where the FT-101E sometimes falls short is in a poorly maintained or partially failed state: solid-state component drift in the front end can silently degrade sensitivity in ways that are harder to detect than tube failure in the Collins.
The crystal lattice filter’s passband has less ideal shape factor than the Collins mechanical filter: the skirts are less steep and the passband has more ripple. In practice, on a quiet band, the difference between the two filters is small. Under contest conditions with multiple close-in strong signals, the Collins filter maintains cleaner audio. The FT-101E’s AGC has a fast/slow selection that the KWM-2A lacks, which some operators find useful for CW operation (fast AGC) vs SSB (slow AGC).
Receiver sensitivity is excellent in a correctly restored FT-101E, competitive with the KWM-2A on the same band. Where the FT-101E sometimes falls short is in a poorly maintained or partially failed state: solid-state component drift in the front end can silently degrade sensitivity in ways that are harder to detect than tube failure in the Collins.
Section 5 — Transmit Performance
Spectral Purity: The Collins Mechanical Filter Advantage
The most significant transmit performance difference between the two transceivers is spectral purity. The Collins KWM-2A generates its SSB signal using the mechanical filter for carrier suppression and unwanted sideband rejection. The mechanical filter’s steep skirts mean that the suppressed sideband is attenuated by 60 dB or more — well within FCC and ITU-T specifications and a standard that most crystal lattice filter designs of the FT-101E era cannot match on a component-for-component basis.
The FT-101E uses a crystal lattice filter for SSB generation. A good crystal lattice filter provides adequate sideband suppression for licence compliance, but the mechanical filter’s performance margin is wider. On a spectrum analyser, a well-maintained KWM-2A typically shows a cleaner transmit spectrum than a well-maintained FT-101E, with lower transmitted spurious products and a more symmetric signal envelope.
Final Amplifier Comparison
Collins 6146B Final — Characteristics
The 2×6146B push-pull final in the KWM-2A is one of the most reliable and well-understood high-power tube stages in amateur radio history. The 6146 family (6146, 6146A, 6146B, 6146W) has been produced by numerous manufacturers over seven decades, is still available in new production, and has a large and well-documented service history. Operating the 6146B conservatively — which the KWM-2A’s ALC system encourages — produces a tube life of thousands of hours. The push-pull balanced arrangement provides inherent even-harmonic cancellation, contributing to the KWM-2A’s clean transmit spectrum. Matched pairs are easily found and reasonably priced in 2026.
Yaesu 6JS6C Final — Characteristics
The 2×6JS6C final in the FT-101E was chosen for its combination of cost and power output in the early 1970s. The 6JS6 family (originally a colour television horizontal deflection tube) provides good HF power output but is not as widely produced as the 6146 family. By 2026, the 6JS6C is a SCARCE-tier part as documented in the vk6ada.com.au parts market analysis: NOS military and commercial surplus stock is diminishing, new production is essentially nil, and the community is increasingly reliant on dwindling NOS supplies and on alternatives such as the 6KD6 (which requires an operating point adjustment). The FT-101E’s dependence on the 6JS6C is its single most significant long-term maintainability concern.
✎ The 6JS6C Situation in 2026 — A Practical Warning
Any prospective FT-101E purchaser or restorer should treat the current state of the 6JS6C final tubes as a high-priority assessment item. Test both finals on a calibrated tube tester before any purchase; request documentation of when the finals were last replaced. A FT-101E with original-production 1970s-era 6JS6C tubes that have never been replaced may be operating far outside its original specification. The cost of a matched pair of 6JS6C tubes from reliable NOS sources has risen substantially; budget for this as part of any FT-101E acquisition. The Collins KWM-2A’s 6146B finals are a non-issue by comparison: tested matched pairs are readily available and affordable from multiple suppliers in 2026.
Section 6 — Ergonomics and the Operating Experience
Collins KWM-2A — Operating Character
The KWM-2A’s operating procedure is deliberate and requires learning. The bandswitching sequence, the use of the Collins “set and forget” antenna tuning procedure, the ALC adjustment, and the absence of features like built-in VOX that later operators took for granted all require the operator to understand the radio’s design before using it effectively. Operators who have made the investment describe the KWM-2A as a pleasure to use once understood — the PTO’s smooth tuning, the mechanical filter’s clean audio, and the precision of the 10-turn vernier dial contribute to an operating experience that has no modern equivalent.
The compact chassis and light weight make the KWM-2A genuinely portable in a way the FT-101E is not. Mobile and portable installations of the KWM-2A were common in its production era and remain viable today.
The compact chassis and light weight make the KWM-2A genuinely portable in a way the FT-101E is not. Mobile and portable installations of the KWM-2A were common in its production era and remain viable today.
Yaesu FT-101E — Operating Character
The FT-101E is a more ergonomically complete transceiver by 1970s standards: built-in VOX, front-panel metering for power and ALC, fast/slow AGC selection, the clarifier for fine-tuning, and continuous coverage of all HF bands without crystal accessories. An operator familiar with modern transceivers will find the FT-101E’s layout more intuitive than the KWM-2A’s.
The larger chassis and greater weight make the FT-101E a desk radio in a way the KWM-2A is not. It does not invite portable use and is clearly designed as a fixed shack installation. The front panel layout is generous and the controls are well-spaced, but the overall impression is of a practical, capable workstation rather than the precision instrument character of the Collins.
The larger chassis and greater weight make the FT-101E a desk radio in a way the KWM-2A is not. It does not invite portable use and is clearly designed as a fixed shack installation. The front panel layout is generous and the controls are well-spaced, but the overall impression is of a practical, capable workstation rather than the precision instrument character of the Collins.
Section 7 — Maintainability: A Restorer’s Comparison
Documentation
Both transceivers have good documentation. The Collins KWM-2A service manual is comprehensive and consistent with Collins’s engineering documentation standard — complete schematics, alignment procedures, and parts lists for all production variants. The Yaesu FT-101E service manual is adequate but reflects the less complete documentation culture of Japanese electronics manufacturers of the early 1970s: schematics are sometimes difficult to read and alignment procedures are occasionally ambiguous. Community resources, particularly the FT-101 dedicated forums and the Yahoo/Groups.io reflectors, supplement the official documentation effectively. Both transceivers have active enough communities that documentation gaps are generally bridgeable.
Electronic Components
KWM-2A Electronic Components
The KWM-2A’s all-tube design means that every active device in the radio is a vacuum tube — and vacuum tubes, even after 60 years, are either findable as NOS or are available in current production. The capacitors (electrolytics and bypass types) need replacement as a matter of course, and the carbon composition resistors require checking for drift, but the substitute components are standard catalogue items. The most maintenance-critical unique component is the Collins mechanical filter: if the filter fails, the transmit spectral purity of the KWM-2A is compromised and substitutes are limited to the same types discussed in the R-390A filter context. This is a shared concern across the Collins S-Line ecosystem.
FT-101E Electronic Components
The FT-101E’s hybrid design presents a mixed components picture. The tube-related parts (6JS6C finals, driver tubes) require attention at sourcing as discussed in Section 5. The solid-state components in the driver stages, VFO buffer, and control circuits include transistor types that were standard in 1974 but are now obsolete or substituted. Community resources document substitute transistor types for the most commonly failed positions; an experienced restorer can address these without great difficulty, but a novice restorer will find the solid-state section more opaque than the KWM-2A’s all-tube design. Electrolytic capacitors in the FT-101E are a high-priority replacement item — the combination of age and the heat generated by the hybrid chassis causes electrolytic failure at a higher rate than in the all-tube KWM-2A.
Common Failure Modes by Transceiver
Failure |
KWM-2A |
FT-101E |
|---|---|---|
| Most common first fault | Electrolytic capacitor failure (hum, instability); carbon comp resistor drift | Electrolytic failure (more severe due to heat); 6JS6C weak emission; solid-state driver transistors |
| VFO / frequency stability | PTO coupling wear (F-09 equivalent); slug permeability drift over decades | VFO drift during warm-up (design characteristic); VFO coil slug or trimmer failure |
| Transmit problems | ALC threshold drift (carbon comp); PA tube emission loss; mechanical filter insertion loss | 6JS6C imbalance producing distorted output; ALC maladjustment; driver transistor failure |
| Receive problems | IF transformer lid desoldering (shared with R-390A family); IF tube failure | Front-end transistor drift (silently degrades sensitivity); AGC anomalies from solid-state aging |
| Restoration priority | Electrolytics, resistor check, mechanical filter test, PTO inspection | Electrolytics (urgent — more heat exposure), 6JS6C test/replace, transistor check, VFO adjustment |
| Unique hazards | HV on PA plates (~800 V); mechanical filter scarcity if failed | HV on PA plates (~600 V); 6JS6C grid current damage if driven without matched pair; overdriven solid-state sections from failed PA |
| Restoration difficulty | Moderate — all-tube is conceptually simple; documentation good | Moderate to hard — hybrid requires both tube and solid-state knowledge; some documentation gaps |
Section 8 — Active Restoration Services (2026)
Service provider status changes frequently. The restoration services listed below were identified as active as of early 2026 based on community reports, website presence, and recent forum activity. Always confirm current operating status, lead time, and pricing directly with any service provider before shipping equipment. The vintage transceiver restoration community is largely composed of individual specialists, some of whom retire or reduce availability without public announcement. QRZ.com operator pages, the Collins Collectors Association technical forum, and the Yaesu FT-101 Yahoo/Groups.io reflector are the most reliable current sources for updated service recommendations.
Collins KWM-2A Restoration Services
◆ Collins Collectors Association (CCA)
The CCA technical resource network is the primary community reference for KWM-2A service. The CCA maintains a roster of technically qualified members who offer restoration services; contact via the CCA forum is the best starting point for a referral. CCA also maintains the Collins technical archive including service bulletins and production change records essential for correct KWM-2A restoration.
collinsradio.org • Technical forum • Service referral network
collinsradio.org • Technical forum • Service referral network
◆ Collins S-Line Community Specialists
Several individual specialists advertise KWM-2A restoration services through QRZ.com and the CCA forums. These are typically retired engineers or long-time collectors with deep S-Line experience. Search QRZ.com for “Collins KWM-2 restoration service” and verify current availability. Community recommendations via the CCA email list are more reliable than general web searches for finding active specialists with current capacity.
◆ Antique Radio Forums — Vintage Ham Restoration
The ARF (Antique Radio Forums) vintage ham section includes restorers who work on Collins S-Line equipment. A “service wanted” post with the unit description and fault symptoms typically produces specialist referrals within days. ARF members who have had Collins work done can provide first-hand service quality assessments, which is the most reliable pre-selection tool available.
antiqueradios.com/forums
antiqueradios.com/forums
◆ vk6ada.com.au / r-390a.net Community Referral
The r-390a.net community, while focused on the R-390A receiver, has documented many KWM-2A and S-Line restorations and maintains informal referral relationships with Collins specialists in Australia, the US, UK, and Europe. Contact via the r-390a.net site for community referrals, particularly for Australian and Asia-Pacific restorers where shipping to US specialists may be cost-prohibitive.
r-390a.net • Community referrals
r-390a.net • Community referrals
Yaesu FT-101E Restoration Services
◆ FT-101 Yahoo / Groups.io Reflector
The FT-101 dedicated email reflector is the primary community for FT-101 series service. The group includes members who have restored dozens of FT-101 series transceivers and who provide referrals to active service providers. Posting a service enquiry with unit description typically produces multiple specialist recommendations. The reflector is also the best source for 6JS6C tube sourcing guidance, substitute transistor specifications, and alignment procedure clarifications.
Search: “FT-101 groups.io” for the current active group
Search: “FT-101 groups.io” for the current active group
◆ eHam.net and QRZ.com Swapmeet / Technical Forums
Both eHam.net and QRZ.com have active communities of FT-101 series restorers. The eHam FT-101 review thread has accumulated service recommendations over many years; the QRZ.com technical forum has active FT-101 threads. Service provider recommendations from these forums tend to reflect current operator experience more accurately than general web searches. Prioritise recommendations from posts within the past 12 months to identify currently active providers.
◆ Vintage Japanese Transceiver Specialists
Several US-based specialists focus on vintage Japanese transceivers from the FT-101 / IC-701 / TS-520 era. These technicians typically have the experience with the hybrid design, the solid-state section failure modes, and the 6JS6C tube sourcing knowledge required for a correct FT-101E restoration. Search QRZ.com for current active listings; community referrals from the FT-101 reflector are the most reliable method of identifying currently active specialists with positive track records.
◆ Local Amateur Radio Clubs — Technical Resources
For Australian restorers in particular, local amateur radio clubs often have members with FT-101 restoration experience. The FT-101 series was enormously popular in Australia during its production era and a significant number of experienced operators and restorers are within the amateur radio club community. The Wireless Institute of Australia (WIA) club directory is a starting point; enquiry through a local club will often produce a recommendation for an experienced local restorer who does not advertise publicly.
Section 9 — Side-by-Side Summary and Verdict
┌──────────────────────────────────────────────────────────────────────────┐ │ COLLINS KWM-2A vs YAESU FT-101E — COLLECTOR’S DECISION GUIDE 2026 │ └──────────────────────────────────────────────────────────────────────────┘ CHOOSE THE COLLINS KWM-2A IF: ┌────────────────────────────────────────────────────────────────────────┐ │ ✓ You want the finest SSB transmit signal quality of the valve era │ │ ✓ You operate primarily on 14, 21, or 28 MHz (standard band crystal) │ │ ✓ You prize VFO stability and dial precision above ergonomic features │ │ ✓ You want an investment-grade collector piece in rising value │ │ ✓ You prefer all-tube design for conceptual clarity of restoration │ │ ✓ You intend to build a matching Collins S-Line station │ │ ✓ You want the lightest and most compact viable HF transceiver │ │ ✓ You plan mobile or portable HF operation │ │ ✗ You need 40m, 80m, or 160m without sourcing crystal accessories │ │ ✗ You want a self-contained shack with no companion units required │ └────────────────────────────────────────────────────────────────────────┘ CHOOSE THE YAESU FT-101E IF: ┌────────────────────────────────────────────────────────────────────────┐ │ ✓ You want complete 160m–10m coverage from day one, no accessories │ │ ✓ You value modern ergonomics: VOX, front-panel metering, clarifier │ │ ✓ You operate on all HF bands and change bands frequently │ │ ✓ You want a single-box shack without companion units │ │ ✓ You have both tube and solid-state restoration experience │ │ ✓ You can source matched 6JS6C finals or have a supply secured │ │ ✓ You want the radio that defined amateur HF in the 1970s │ │ ✗ You need transmit spectral purity matching the Collins standard │ │ ✗ You are concerned about obsolete solid-state component sourcing │ │ ✗ You want to avoid 6JS6C tube availability anxiety │ └────────────────────────────────────────────────────────────────────────┘ CATEGORY SCORECARD ┌──────────────────────────────────┬──────────────────┬──────────────────┐ │ Category │ Collins KWM-2A │ Yaesu FT-101E │ │ ────────────────────────────── │ ────────────── │ ────────────── │ │ VFO stability and precision │ ●●●●● │ ●●●○○ │ │ Transmit spectral purity │ ●●●●● │ ●●●○○ │ │ Band coverage (standard) │ ●●○○○ │ ●●●●● │ │ Receive selectivity │ ●●●●● │ ●●●○○ │ │ Receive sensitivity │ ●●●●○ │ ●●●●○ │ │ Ergonomics and features │ ●●●○○ │ ●●●●○ │ │ Parts availability (2026) │ ●●●●● │ ●●●○○ │ │ Restoration documentation │ ●●●●● │ ●●●○○ │ │ Restoration complexity │ ●●○○○ (simpler) │ ●●●○○ (harder) │ │ Collector value trajectory │ ●●●●● │ ●●●○○ │ │ Complete-station ergonomics │ ●●●○○ │ ●●●●● │ │ Portability │ ●●●●● │ ●●○○○ │ └──────────────────────────────────┴──────────────────┴──────────────────┘ COMBINED ASSESSMENT ───────────────────────────────────────────────────────────────────────── Neither radio is universally superior. The Collins KWM-2A is the better transceiver by every technical engineering criterion that Collins applied to its design: spectral purity, VFO stability, selectivity, transmit linearity. It is not a better transceiver for an operator who needs 160m, all-band coverage in one box, or the ergonomic feature set of the 1970s. The FT-101E is the better choice for an operator who wants complete HF coverage, modern operating ergonomics, and a radio that represents the dominant amateur transceiver design philosophy of its era. It is not a better choice for an operator who prioritises transmit quality, long-term parts security, or the all-tube design aesthetic. In 2026, the Collins KWM-2A has a measurable maintainability advantage that will grow over time: the 6146B tube supply is stable; the 6JS6C supply is not. A collector who acquires a correctly restored KWM-2A today will face lower parts cost and less sourcing anxiety in five years than a collector with an FT-101E requiring fresh finals. This is not a reason to avoid the FT-101E — it is a reason to budget for the 6JS6C situation at acquisition time.
Collins KWM-2A vs Yaesu FT-101E comparison summary. Category scores are community consensus assessments, not instrument measurements; individual unit condition significantly affects real-world performance in both cases.
The honest answer for 2026. If you can only have one, choose the radio you will actually operate and enjoy. Both are capable of excellent amateur communications. The Collins KWM-2A rewards the operator who invests time in learning its procedures and respects its technical heritage. The Yaesu FT-101E rewards the operator who wants to be on all bands immediately and appreciates the Japanese pragmatic engineering tradition. Both are worth restoring, worth operating, and worth preserving. The community is large enough and the parts situation is manageable enough for both that the choice in 2026 is genuinely a preference decision, not a practicality decision — with the one caveat that the FT-101E buyer should sort out the 6JS6C situation before anything else.
References and Notes
- Collins Radio Company, KWM-2 / KWM-2A Operating and Service Instructions. Available through the Collins Collectors Association at collinsradio.org and the Virtual Collins Radio Museum at wa3key.com. Primary source for KWM-2A specifications, circuit descriptions, alignment procedures, and variant differences. All KWM-2A specifications cited in this comparison are derived from the factory service documentation; verify from the applicable edition for the specific unit serial number range.
- Yaesu Musen Co. Ltd., FT-101E Operating and Service Manual. Available through the FT-101 reflector community and vintage transceiver documentation archives. The FT-101E service manual, while adequate, contains some ambiguities in the alignment procedure and should be supplemented with community errata available through the FT-101 Groups.io reflector before undertaking alignment work.
- Collins Collectors Association, KWM-2 / KWM-2A Service Bulletins and Technical Notes, collinsradio.org/cca-collins-historical-archives/. Factory service bulletins covering KWM-2A production changes and known fault corrections. The Collins service bulletin index at vk6ada.com.au/collins-service-bulletin-index/ cross-references all relevant bulletins.
- Mike Peace VK6ADA, Collins KWM-2A Failure Prevention Kit, vk6ada.com.au. The dedicated failure prevention kit for the KWM-2A, covering the S-Line shared failure modes (mechanical filter, PTO coupling, carbon comp resistors) in the transceiver context. Cross-referenced for the restoration complexity assessment in Section 7 of this comparison.
- Mike Peace VK6ADA, Yaesu FT-101E Failure Prevention Kit, vk6ada.com.au. The dedicated failure prevention kit for the FT-101E, covering electrolytic capacitor priorities, 6JS6C tube assessment, solid-state driver section failures, and VFO drift diagnosis. The failure mode table in Section 7 of this comparison is consistent with the FPK failure taxonomy.
- FT-101 Yahoo Groups / Groups.io reflector, archived community discussions. Source for community consensus assessments of the FT-101E’s solid-state component failure rates, 6JS6C tube availability assessments, and restoration difficulty characterisation. The reflector archive is the primary evidence base for the FT-101E-specific entries in the restoration comparison table.
- eHam.net, Yaesu FT-101E reviews and technical forum threads, and Collins KWM-2A reviews. Operator experience reports from multiple decades of use, providing the primary source for operating experience characterisations in Section 6 and the scorecard assessments in Section 9. Individual operator assessments vary; the scorecard reflects community consensus across multiple independent reviews rather than any single operator’s experience.
✍ Mike Peace VK6ADA / r-390a.net Administrator • March 2026
vk6ada.com.au — Collins Radio Technical Resource