Web-888 with the Collins KWM-2A
Integration Options, Station Architecture, and Eight Best-Practice Operating Procedures
The KWM-2A is a transceiver. Every decision about how the Web-888 connects to it flows from that single fact — its TX and RX share one antenna connector, one PTO, one set of band crystals. There is no dual-PTO alignment problem. There is no ALC cable between separate units to protect. There is, however, an internal T/R relay that switches full PA power to the antenna connector during transmit, which creates a protection requirement that the S-Line’s external antenna path does not. This guide covers the three practical integration options and the operating procedures that extract the most value from the Web-888 as a KWM-2A companion.
The KWM-2A and the S-Line present different Web-888 integration problems. In the S-Line station, the 75S-3 and 32S-3 have separate antenna connectors and a dual-PTO frequency alignment problem that the Web-888 panadapter elegantly solves. In the KWM-2A station, there is no dual-PTO alignment problem at all — the single PTO controls both TX and RX simultaneously, so whatever frequency the dial shows is both the transmit and receive frequency. This removes an entire category of operating discipline from the Web-888’s job description.
What the KWM-2A has instead is the internal T/R relay challenge. Because the KWM-2A’s antenna connector is bidirectional — it is a receiver input during RX and carries full PA power during TX — connecting the Web-888 to the antenna connector without a protection mechanism that tracks the KWM-2A’s internal T/R switching is unsafe. The solution options each have different trade-offs in complexity, cost, and operational capability. This guide ranks them, explains the trade-offs, and then documents the eight operating procedures that apply to whichever approach is selected.
Section 1 — KWM-2A Architecture: What Matters for Web-888 Integration
The Single PTO — the KWM-2A’s Core Advantage Over the S-Line
The Collins KWM-2A uses a single PTO (Permeability Tuned Oscillator) that simultaneously generates the local oscillator frequency for both the receiver section and the transmitter section. When the operator rotates the PTO dial, both the receive frequency and the transmit frequency change identically and instantaneously. There is no separate 32S-3 transmitter to set, no frequency alignment to verify, no possibility of transmitting on the wrong frequency because of a PTO mismatch. The Web-888’s panadapter shows the operating frequency; the KWM-2A transmits on that same frequency automatically.
This single-PTO architecture is the KWM-2A’s most significant operational advantage in a Web-888-augmented station: the frequency verification step that occupies an entire section of the S-Line Web-888 guide simply does not exist here. The Web-888 panadapter is never wrong about where the KWM-2A is operating, because there is only one frequency to be wrong about.
The Internal T/R Relay
The KWM-2A’s internal T/R (transmit/receive) relay is the component that manages the share of the antenna connector between the receiver front-end (during RX) and the PA output (during TX). When the PTT is depressed, the relay activates: the receiver front-end is disconnected from the antenna connector, and the PA output is connected. When PTT is released, the relay returns to the receive position.
This relay protects the KWM-2A’s own receiver front-end from the PA output. It does not protect any external device connected to the antenna connector during transmit. Any such device sees the full PA output power during transmit unless it has its own protection mechanism.
KWM-2A Station Companion Units
The KWM-2A is designed to be self-contained for basic operation but is typically paired with:
- Collins 312B-4 speaker/console — provides the loudspeaker for received audio, the CW sidetone control, and the station monitor meter. Standard companion unit; the KWM-2A’s audio output is at headphone level and the 312B-4 provides speaker amplification and the visible meter for power and ALC monitoring.
- Collins 30L-1 linear amplifier — optional; increases output power. If a 30L-1 is in the station, the Web-888 integration must also accommodate the amplifier’s antenna connection and T/R switching. The 30L-1 has its own T/R relay that follows the KWM-2A’s PTT keying; the Web-888 protection architecture must be coordinated with the amplifier’s keying sequence as well.
- Web-888 SDR — the panadapter and TX quality monitor that this guide addresses.
Section 2 — Three Integration Options: Comparison and Selection
The Web-888 can be integrated with the KWM-2A in three practical ways. Each provides different capabilities and requires different levels of hardware modification or external equipment. The options are presented in recommended priority order.
Which Option to Choose
Priority |
Option 1 — IF Tap |
Option 2 — Directional Coupler |
Option 3 — Monitor Antenna |
|---|---|---|---|
| Panadapter — RX | Excellent; tracks PTO, front-end gain, filtered | Good; unfiltered wide view; manual alignment needed | Adequate; less sensitive; manual alignment needed |
| TX quality monitor | Not available (IF inactive during TX) | Excellent; real-time on-air quality view | Limited; enough to verify frequency, not quality |
| Installation complexity | Moderate — chassis work, rear panel BNC | Low — external connections only | Minimal — one cable |
| Web-888 protection | Inherent — IF strip inactive during TX | Provided by coupler + attenuator calculation | Inherent — physical separation |
| Recommended for | Operators focused on RX panadapter; DX pre-selection; willing to do chassis work | Operators focused on TX quality; prefer no chassis work; combine with Option 1 for complete capability | Operators wanting basic SDR capability with minimum setup; CW/casual operating |
Section 3 — Option 1: The IF Tap — CASCADE-KWM Installation
The CASCADE-KWM IF tap follows exactly the same principles as the CASCADE-390 kit for the R-390A, documented in the vk6ada.com.au RX-888 Mk II cascade integration guide. The KWM-2A’s IF chain operates at 455 kHz, the same as the R-390A. A high-impedance buffered tap extracts a sample of the IF signal before the Collins mechanical filter (the pre-filter tap position provides the widest panadapter view, typically several hundred kilohertz of usable bandwidth around the KWM-2A’s tuned frequency).
When the Web-888 receives the KWM-2A’s 455 kHz IF output, the OpenWebRX frequency display must be offset to show the correct HF frequency. The relationship is identical to the R-390A case:
IF offset (Hz) = KWM-2A dial reading (Hz) − 455,000 HzExample: KWM-2A tuned to
14.175 MHz → IF offset = 14,175,000 − 455,000 = 13,720,000 Hz (13.720 MHz)The Web-888’s OpenWebRX display then shows
14.175 MHz at the centre of the panadapter, with signals visible at their correct HF frequencies. Since the KWM-2A has only one PTO governing both TX and RX, there is no need to update the offset when moving between TX and RX. Update the offset only when the KWM-2A is retuned significantly (band change, or moving more than 1 MHz within a band segment). Within a PTO segment, the offset is constant.
The IF tap installation inside the KWM-2A chassis follows the same procedure as the CASCADE-390 kit installation:
-
1
Power off; discharge B+ below 30 V before any chassis access Measure the B+ bus with a DVM after switch-off. The KWM-2A’s PA plate voltage (approximately 800 V DC) drops through the bleeder network; do not open the chassis until the DVM reads below 30 V. The KWM-2A has less B+ capacitance than the R-390A but the discharge time should still be verified by measurement.
-
2
Locate the KWM-2A pre-filter IF tap point from the service manual The KWM-2A service manual identifies the component at the 455 kHz IF input to the Collins mechanical filter. This is the optimal pre-filter tap point. Contact vk6ada.com.au for the current CASCADE-KWM kit documentation which identifies the specific component lead and the connection method for the RG-174 tap lead.
-
3
Install the CASCADE-KWM buffer PCB and rear-panel BNC Mount the buffer PCB at a suitable chassis location (typically near the IF section). Drill the rear-panel BNC aperture using a stepped drill bit from outside the chassis. Route a short RG-174 coax from the tap point to the PCB input. Connect the PCB output to the rear-panel BNC. Power the buffer from the B+ supply via a dropping resistor network as specified in the kit documentation. All connections are reversible; no permanent modification to the KWM-2A’s signal path is made.
-
4
Verify KWM-2A receives normally; verify Web-888 shows IF signal Power on via Variac. Confirm the KWM-2A receives on all bands with normal sensitivity. Connect a short BNC cable from the rear-panel BNC to the Web-888 HF input. Open the Web-888’s OpenWebRX interface, set the centre frequency to
455 kHz, and verify that signals appear on the panadapter that shift position as the KWM-2A is tuned. If signals shift correctly, the IF tap is working. Apply the IF offset in OpenWebRX settings to display the correct HF frequency.
Section 4 — Option 2: Directional Coupler for TX Quality Monitoring
The Attenuation Calculation
A directional coupler inserted in the antenna path after the KWM-2A antenna connector samples a small fraction of the transmitted signal. The coupled output must be attenuated to a level safe for the Web-888’s HF input. The Web-888’s maximum safe input power is typically specified around −10 dBm (0.1 mW); confirm from the Web-888 specifications for the specific unit.
KWM-2A PA output:
100 W = +50 dBmWeb-888 maximum safe input:
−10 dBmRequired total attenuation:
50 dBm − (−10 dBm) = 60 dBRecommended configuration:
30 dB directional coupler + 30 dB attenuator pador:
40 dB directional coupler + 20 dB attenuator padA 30 dB directional coupler + 30 dB N-type or BNC attenuator pad provides exactly 60 dB total attenuation at 100 W input, giving approximately −10 dBm at the Web-888 input — at the safe upper limit. Use a 30 dB coupler + 35 dB pad (or equivalent) to provide a 5 dB safety margin: this gives −15 dBm at the Web-888 input at 100 W PA output.
With a 30L-1 linear amplifier in the chain: if the 30L-1 is in use, the antenna path carries approximately 800 W PEP at its rated output. Recalculate:
+59 dBm (800 W) − (−10 dBm) = 69 dB required total attenuation. Use a 40 dB directional coupler + 30 dB attenuator pad (70 dB total, providing 1 dB safety margin). The attenuator must be rated for the power level at its input port; a 30 dB attenuator in the coupler output path sees much lower power than the main line, but the attenuator’s own power rating must still exceed the coupled power level.
Directional Coupler Placement
Place the directional coupler between the KWM-2A antenna connector and the antenna feedline (or the CX-140D T/R switch if one is installed for a 30L-1 keying arrangement). The directional coupler’s main-line ports are in the signal path; the coupled port connects to the attenuator pad and thence to the Web-888. The directional coupler’s main-line insertion loss is typically <0.3 dB for good quality HF directional couplers (Mini-Circuits, Narda, or equivalent) — this loss is negligible for practical operation.
Section 5 — OpenWebRX Band Profile Configuration for the KWM-2A
The KWM-2A’s standard band coverage (14–29.7 MHz without crystal accessories; 3.5 and 7 MHz with 80m and 40m band crystals) drives the OpenWebRX band profile configuration. Create separate profiles for the IF tap input (Option 1) and the directional coupler input (Option 2) if both are installed — they are connected to different physical inputs and require separate device definitions in OpenWebRX.
Band |
KWM-2A Coverage |
Sideband |
IF Tap Profile Centre |
Coupler Profile Centre |
Span (approx.) |
|---|---|---|---|---|---|
| 80m | 3.500–4.000 MHz (crystal) | LSB | 455 kHz + offset = 3.75 MHz |
3.750 MHz | 500 kHz |
| 40m | 7.000–7.500 MHz (crystal) | LSB | 455 kHz + offset = 7.15 MHz |
7.150 MHz | 500 kHz |
| 20m | 14.0–14.5 MHz (standard) | USB | 455 kHz + offset = 14.175 MHz |
14.175 MHz | 500 kHz |
| 17m (CP-1) | 18.068–18.168 MHz (CP-1) | USB | 455 kHz + offset = 18.118 MHz |
18.118 MHz | 200 kHz |
| 15m | 21.0–21.5 MHz (standard) | USB | 455 kHz + offset = 21.225 MHz |
21.225 MHz | 500 kHz |
| 10m | 28.0–29.7 MHz (standard) | USB | 455 kHz + offset = 28.500 MHz |
28.500 MHz | 1 MHz |
455 kHz for all bands. The IF offset value changes for each band (because the KWM-2A dial reading changes); update the offset when changing bands or after retuning significantly within a band. The IF offset column in the table above shows the offset value for the approximate band centre frequency; recalculate from the dial reading for any specific operating frequency. For the directional coupler profiles (Option 2), set the SDR centre to the HF operating frequency directly — no IF offset calculation is needed.
Section 6 — Eight Best-Practice Operating Procedures for the KWM-2A + Web-888 Station
-
Use the Web-888 Waterfall to Monitor PTO Warm-Up Drift
The KWM-2A’s PTO drifts during the first 15–20 minutes of operation as the chassis reaches thermal equilibrium. Using the IF tap approach, the Web-888 waterfall shows this drift directly: a known signal (WWV, for example, which can be identified on the waterfall from its time marks) appears as a diagonal trace during warm-up — the trace slopes as the PTO drifts. When the slope flattens, the PTO has stabilised and the station is ready for serious operating. This replaces the informal “warm up for 15 minutes before tuning” discipline with a visible, objective indicator of when the PTO is actually stable. An experienced KWM-2A operator can read the drift rate from the waterfall slope and predict when stabilisation will occur, which is useful for scheduling contacts during warm-up.
-
Use the Panadapter for DX Pre-Selection Before Tuning the KWM-2A
The KWM-2A’s 10-turn vernier PTO dial is precise within a 1 MHz segment but is not a band-scanning instrument. The operator must tune through the band by ear to identify DX activity. With the Web-888 panadapter showing the IF band content (via the IF tap), signal clusters are immediately visible without audio scanning. A DX station’s pile-up appears as a cluster of peaks on the panadapter; the DX station itself appears as a distinct peak, typically slightly offset from the pile-up cluster in split operation. Identify both the DX frequency and the split-working frequency visually on the panadapter before touching the KWM-2A dial. This approach is faster and more precise than audio scanning and is particularly valuable when looking for weak DX in a noisy band environment.
-
Monitor Every SSB Transmission on the Directional Coupler Profile for Signal Quality
The most important single benefit of the directional coupler configuration (Option 2) is the ability to observe the KWM-2A’s transmitted signal on the Web-888 panadapter during active transmission. A correctly operating KWM-2A produces a clean SSB envelope approximately 2.5–3 kHz wide during normal speech, with no significant energy appearing beyond ±3 kHz from the carrier frequency. The ALC system limits the peak drive level so that the signal amplitude varies with speech content but the spectral width remains approximately constant. If the panadapter shows spurious sidebands or abnormal spectral width, investigate the ALC system and drive level settings before continuing to transmit.
Switch the Web-888 OpenWebRX input to the directional coupler profile before transmitting to monitor your own signal. Switch back to the IF tap profile after transmission to return to the receive-mode panadapter. With both hardware options installed, this switching is a one-click operation in the OpenWebRX browser interface.
-
The Single-PTO Limitation in Split-Frequency Operation — Web-888 Awareness
The KWM-2A’s single PTO means the transmit and receive frequencies are always the same. True split-frequency operation (transmitting on one frequency while listening on another) is not directly possible without additional hardware (a second VFO or a separate receive radio). This is the one significant operational limitation of the KWM-2A relative to modern transceivers for DX pile-up operation.
The Web-888 panadapter partially compensates: in a DX pile-up where the DX station is listening up (the standard practice), the operator can use the Web-888 panadapter to identify exactly where the DX station is listening by watching where the DX station’s responses occur on the waterfall. The operator then tunes the KWM-2A to that frequency and calls. This is not true split-frequency operation but it is the most informed single-VFO DX pile-up strategy available for the KWM-2A. The panadapter makes it significantly more effective than the traditional “listen around the pile-up by ear” approach.
-
Verifying KWM-2A ALC Operation Via Web-888 Panadapter
The KWM-2A’s internal ALC system regulates the transmit drive level, keeping the PA within its rated operating envelope and maintaining clean SSB spectral occupancy. The Web-888 panadapter provides a direct visual assessment of whether the ALC is functioning correctly without requiring a separate station monitor or another operator’s report.
Correct ALC behaviour: during speech transmission, the signal peak on the panadapter rises and falls with speech amplitude but remains approximately 2.5–3 kHz wide at all speech levels. The peak amplitude should vary by approximately 10–15 dB between loud and quiet speech; during pauses between words, the signal should drop to or near the noise floor. If the signal width increases significantly during loud speech (broader than 3 kHz), the ALC is not limiting effectively. If the signal width remains narrow even at peak speech levels but the amplitude is uncharacteristically high, the ALC threshold may be set too high. Either condition warrants investigation of the ALC circuit at the KWM-2A before further operating.
-
CW Key Click Assessment via Directional Coupler Profile
CW key clicks — transmitted sidebands generated by excessively fast RF rise and fall times at the beginning and end of each transmitted element — are visible on the Web-888 panadapter as broadened spectral edges on each element boundary. During continuous CW sending, the Web-888 should show a narrow, well-defined carrier peak that switches on and off cleanly. Broadened edges or splatter sidebands visible on the panadapter indicate key-click problems that should be addressed at the KWM-2A’s keying circuit before competing in environments where spectral cleanliness matters.
This CW signal quality assessment via the panadapter is available without requiring any other station to monitor your signal and report. The Web-888 directional coupler profile allows the KWM-2A operator to assess their own CW signal quality on any band at any time, which is the most direct available feedback for maintaining good operating practice.
-
Band Change Procedure with Web-888 IF Tap Profile
When the KWM-2A changes band (changing band crystals), the IF offset in the Web-888’s OpenWebRX profile must be updated to reflect the new operating frequency. The procedure: change the KWM-2A band crystal; rotate the PTO dial to the desired operating frequency; read the dial; update the OpenWebRX IF offset in the device configuration (
new offset = new frequency − 455 kHz); verify the new centre frequency appears correctly in the panadapter by tuning to a known signal.For operators who change bands frequently, pre-configured OpenWebRX profiles for each band (with the centre-of-band IF offset pre-calculated) allow rapid switching. Select the 20m IF tap profile when moving to 20m; select the 40m IF tap profile when moving to 40m. Fine-tune the offset for the specific operating frequency within the band by adjusting the OpenWebRX offset field. This is faster than recalculating the offset from scratch on each band change.
-
Collins 30L-1 Integration — Increased Attenuation Requirement
If the KWM-2A station includes a Collins 30L-1 linear amplifier, the directional coupler attenuation calculation must be recalculated for the 30L-1’s rated output power (approximately 800 W PEP SSB). As documented in Section 4, this requires approximately 69 dB total attenuation at the Web-888 input for a −10 dBm maximum safe input level. The coupler + pad combination must be rated accordingly, and the attenuator pad must be rated for the power it receives from the coupled port of the directional coupler.
The 30L-1 also adds a T/R relay in the antenna path that is keyed by the KWM-2A’s PTT. The directional coupler should be placed between the 30L-1’s antenna output port and the antenna feedline (not between the KWM-2A and the 30L-1) so that it monitors the final output including amplifier gain, not the KWM-2A’s exciter-only output. The IF tap (Option 1) is unaffected by the 30L-1’s presence and requires no modification for amplifier integration.
Section 7 — Complete KWM-2A + Web-888 Station Architecture
┌──────────────────────────────────────────────────────────────────────────┐
│ COLLINS KWM-2A + WEB-888 — COMPLETE STATION ARCHITECTURE │
│ Combined Option 1 (IF tap) + Option 2 (directional coupler) │
└──────────────────────────────────────────────────────────────────────────┘
KWM-2A INTERNAL ARCHITECTURE (reference for integration context):
┌──────────────────────────────────────────────────────────────────────────┐
│ Single PTO ──────────┬────────────► Receiver LO (RX frequency = TX freq)│
│ (0–1 MHz range) └────────────► Transmitter LO (same frequency) │
│ │
│ Antenna connector ───┬── RX position: → Receiver front-end (sensitive) │
│ (SO-239) └── TX position: ← PA output (~100W / ~800V DC) │
│ (switched by internal T/R relay on PTT) │
└──────────────────────────────────────────────────────────────────────────┘
─────────────────────────────────────────────────────────────────────────
OPTION 1: IF TAP (CASCADE-KWM) — panadapter that tracks PTO automatically
─────────────────────────────────────────────────────────────────────────
[KWM-2A IF strip at 455 kHz, pre-filter tap point]
│
[CASCADE-KWM buffer PCB] ── powered from KWM-2A B+
│ 50 Ω BNC output on rear panel
│ short BNC cable
▼
[Web-888 HF antenna input]
│ USB 3.0 → computer
[OpenWebRX — IF tap profile]
Centre frequency: 455 kHz
IF offset: (KWM-2A dial reading) − 455,000 Hz
→ Panadapter shows HF frequencies centred on KWM-2A PTO dial reading
→ During TX: IF strip has no signal (internal T/R relay disconnects RX)
→ Web-888 completely safe during TX; no external T/R switch needed
─────────────────────────────────────────────────────────────────────────
OPTION 2: DIRECTIONAL COUPLER — TX quality monitor (external, no chassis work)
─────────────────────────────────────────────────────────────────────────
KWM-2A antenna connector (SO-239)
│
[30 dB directional coupler] ──── main line: to antenna / 30L-1 / CX-140D
│ coupled port: ~0.1W at 100W PA out (+20 dBm)
[30 dB attenuation pad] ──────── (rated ≥1W; 35 dB for 5 dB safety margin)
│ ~−15 dBm at Web-888 input (100W PA, 35 dB pad, 30 dB coupler)
[Web-888 HF antenna input]
[OpenWebRX — directional coupler profile]
Centre frequency: HF operating frequency directly (no IF offset)
→ Shows transmitted signal on panadapter during TX
→ Shows received signal on panadapter during RX (attenuated)
─────────────────────────────────────────────────────────────────────────
COMBINED CONFIGURATION (both options installed, Web-888 RX input switches)
─────────────────────────────────────────────────────────────────────────
Web-888 has two antenna inputs in some configurations (SMA + secondary BNC)
OR: use an external BNC A/B switch between IF tap output and coupler output
→ Select IF tap input for receive-mode panadapter (DX spotting, band watching)
→ Select coupler input for TX monitoring (signal quality assessment)
Input selection: manual switch OR two OpenWebRX device profiles
─────────────────────────────────────────────────────────────────────────
KEY DISTINCTION FROM S-LINE WEB-888 INTEGRATION
─────────────────────────────────────────────────────────────────────────
┌────────────────────────────────────┬──────────────────────────────────┐
│ S-Line (75S-3 + 32S-3) │ KWM-2A │
│ ──────────────────────────────── │ ────────────────────────────── │
│ Two PTOs — must be aligned │ One PTO — always aligned │
│ Separate TX and RX antennas OK │ Single antenna connector — must │
│ External T/R switch for both │ protect against internal T/R PA │
│ Web-888 verifies TX-RX alignment │ Web-888 shows drift, band, TX q │
│ ALC cable between TX and RX │ ALC internal — no cable concern │
│ Main Web-888 benefit: freq check │ Main benefit: PTO drift + TX mon │
└────────────────────────────────────┴──────────────────────────────────┘
─────────────────────────────────────────────────────────────────────────
TX QUALITY REFERENCE TABLE (directional coupler profile — what to look for)
─────────────────────────────────────────────────────────────────────────
CORRECT KWM-2A SSB: ~2.5–3 kHz wide; peaks with speech; null between
sidebands; no energy beyond ±3 kHz
CORRECT KWM-2A CW: Narrow carrier; clean on/off; no broadened edges
PROBLEMS:
Wider than 3 kHz → ALC not limiting; overdrive; check ALC level
Residual carrier → Balanced modulator null; carrier injection adjustment
Key-click sidebands → Keying rise/fall time; anti-click network
Signal off-frequency → KWM-2A PTO mismatch vs calibrated reference
Constant amplitude → ALC over-compression; set ALC control lower
Collins KWM-2A + Web-888 station architecture showing Option 1 (IF tap, recommended for receive panadapter) and Option 2 (directional coupler, for TX quality monitoring). Attenuation values shown are calculated for 100 W KWM-2A PA output and a Web-888 maximum safe input of −10 dBm; recalculate for the specific Web-888 variant’s input specification and for use with the 30L-1 linear amplifier. See Section 4 for the 30L-1 calculation. IF offset values must be updated when the KWM-2A is retuned significantly; within a PTO segment, the offset is constant because the KWM-2A’s single PTO governs both TX and RX simultaneously.
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 (wa3key.com). The service manual is the authoritative reference for the IF circuit tap point location (the component at the 455 kHz IF input to the Collins mechanical filter), the internal T/R relay function, the ALC system description, and the PA plate voltage specification. The IF tap point component designator is identified in the CASCADE-KWM kit documentation available from vk6ada.com.au.
- Mike Peace VK6ADA, RX-888 Mk II with the Collins R-390A — Practical Cascade Integration via the CASCADE-390 IF Tap Kit, vk6ada.com.au (March 2026). Primary reference for the IF tap methodology, including the 455 kHz offset calculation formula, the buffer amplifier design principles, the OpenWebRX IF offset configuration procedure, and the pre-filter vs post-filter tap point comparison. The CASCADE-KWM kit for the KWM-2A follows identical design principles to the CASCADE-390 kit documented in that guide; all software configuration procedures are transferable directly.
- Mike Peace VK6ADA, Web-888 SDR Integration with Collins S-Line 75S-3 and 32S-3, vk6ada.com.au (March 2026). Companion guide for the S-Line station integration. The distinction between the S-Line’s dual-PTO operating discipline and the KWM-2A’s single-PTO architecture is the central differentiator between the two guides; reading both provides a complete picture of Web-888 integration across the Collins S-Line and KWM-2A product families.
- Mike Peace VK6ADA, Web-888 Remote Access Setup for Vintage Receivers, vk6ada.com.au (March 2026). Primary reference for Web-888 hardware overview, OpenWebRX installation and configuration, network setup (static IP, DDNS, WireGuard VPN), security hardening, and frequency calibration against WWV. The hardware and software foundation documented in that guide is prerequisite to the KWM-2A-specific integration described here.
- Mike Peace VK6ADA, Tohtsu CX-140D Use Cases for Collins S-Line, R-388, R-390, R-390A, Hammarlund SP-600 and HQ-180, vk6ada.com.au (March 2026). Reference for the T/R switching configuration applicable to KWM-2A stations equipped with a Collins 30L-1 linear amplifier. The 30L-1 introduces an additional T/R relay in the antenna path; the CX-140D guide’s Configuration A (T/R switching) applies directly to the 30L-1 + KWM-2A station. The directional coupler placement note in BP-08 (coupler after the 30L-1 output, not between the KWM-2A and 30L-1) is consistent with the CX-140D guide’s discussion of amplifier station configurations.
- Mini-Circuits and Narda Microwave (and equivalent manufacturers), directional coupler datasheets. The directional coupler specifications referenced in Section 4 (30 dB coupling, <0.3 dB main-line insertion loss, 50 Ω throughout HF frequency range) are typical of high-quality HF directional couplers available from Mini-Circuits, Narda, and equivalent RF component manufacturers. Verify the coupling factor, frequency range (must cover 3.5–30 MHz for all KWM-2A bands), maximum main-line power rating, and coupled port connector type from the specific coupler datasheet before installation. The attenuator pad must be separately specified and verified for its power rating at the coupled port power level.