The Transceivers
The Yaesu FT‑991A and FTDX10 provide the radio operating position and transmit capability.
Tour the station ↗The W3UJ station
Expand Your Station with External SDRs
See more. Listen independently. Bring the station together.
SDR stands for Software-Defined Radio. Radio hardware captures signals; software lets you tune, listen, filter, and view activity. Learn what an external SDR receiver can add, plan a basic system, and integrate it with your radio. The W3UJ station demonstrates wider spectrum views, independent reception, and coordinated radio control. Your radio may already use SDR internally; learn how receiver designs differ and why an external SDR may still help. SDR Console is the software platform used here; the FT‑991A and FTDX10 remain the transmitters, with separate RF routing and PTT protection for the SDR receivers.
New to External SDR?Find the Activity
Find the Activity
Choose What to Hear
Imagine leaving your radio on a net while you explore other signals on your computer. An external SDR adds another receiver—and a spectrum and waterfall that show you where to look.
- See activity across frequencies. Find a trace that interests you, click to tune and listen.
- Look closer at a faint signal. Zoom the display and adjust the receive filter to investigate what you can hear.
- Keep your operating frequency. Explore with the external receiver while your transceiver stays tuned to the conversation.
Start with one receiver. Available coverage depends on the hardware and settings; include suitable PTT-controlled protection wherever transmit RF can reach the SDR.
Watch the W3UJ Station Work
This is SDR Console receiving at the W3UJ station—a real operating example of what an external SDR and computer display can bring to your station.
Three Displays. A Different View of the Bands
Already Have an SDR Radio?
There’s More to Explore
Radios such as the IC-7300MKII and Yaesu FTDX10 already offer useful spectrum displays and signal processing. An external SDR with software such as SDR Console adds a flexible computer workspace for seeing activity, exploring signals, and shaping how you listen.
The External SDR Workspace
Actual station screenshot—not a live feed. Select the image to enlarge.
Icom IC-7300MK2
Yaesu FTDX10
Separate captured examples, not live feeds or a matched reception test. Compare the working views—not signal strength or sensitivity. An external SDR adds its own receive path and software workspace.
- See More of the Band
- Use adjustable, detailed waterfalls and whole-band views within the SDR’s available bandwidth. Zoom in on activity that catches your attention.
- Find Faint Activity
- Adjust the display to make weak traces easier to spot, then tune, listen, or decode to judge readability.
- Follow Several Signals
- Open multiple receiver slices within one SDR’s sampled range while leaving your transceiver on its operating frequency.
- Work the Signal
- Use flexible filters, noise-reduction tools, and detailed tuning in a workspace arranged across your computer monitors.
From the Radio’s Display to a Wider SDR Workspace
The examples above show two ways to explore received activity: the scope built into your transceiver and an external SDR working with SDR Console. The Icom and Yaesu displays help you see signals around your operating frequency. An external receiver adds a separate listening path and a computer workspace with adjustable waterfalls, multiple receiver windows, and flexible filtering.
The chart below adds another dimension: how much spectrum you can view or work within at once. It compares built-in scope spans with external SDR instantaneous bandwidth on a shared scale. Wider coverage can help you find activity across a band—or several bands, where supported—then zoom in and investigate individual signals.
Width is only part of the benefit. The advantage comes from combining that broader view with software tools that help you tune, listen, and manage several signals. Actual coverage depends on the hardware, software, and computer; a wider display alone does not guarantee better reception.
Add a second receiver—keep your transceiver’s own receiver. With the appropriate SDRSwitch.com RXin/RXout model and documented wiring, your radio retains its normal receive and transmit functions. The external SDR provides an additional, independently tunable receiving path. Receive-loop and transmit-protection behavior depend on the switch model and configuration. See how the two receivers work together →
Scope Span and Sampled Bandwidth on a Shared Scale
Both groups use the same 0–32 MHz scale.
Built-In Scope Span
- Yaesu FT-991A1 MHz
- Yaesu FTDX101 MHz
- Icom IC-73001 MHz
- Icom IC-7300MKII1 MHz
- Kenwood TS-890S500 kHz
External SDR Instantaneous Bandwidth
- Nooelec NESDR SMArt v52.4 MHz nominal
Up to 3.2 MHz depending on configuration.
- SDRplay RSPduoUp to 10 MHz
Single-tuner operation.
- SDRplay RSPdx-R2Up to 10 MHz
- RX888 MkII32 MHz illustrated
Up to 64 MHz depending on configuration.
How W3UJ works
How the Station Works
The SDR Receivers
External receivers send received samples to the computer over USB. Available spectrum span depends on the receiver, settings, and computer.
See the equipment ↗SDR Console
Use larger waterfalls, multiple receive channels, and filtering. Supported CAT control coordinates radio tuning and mode.
Explore the controls ↗SDR Switches
Route received RF through the coax connections and isolate or ground the SDR input during transmission, according to the switch design and wiring.
Explore the SDR switches ↗PTT Control
Keying signals tell the protection switches when either radio transmits. The PTT wiring is separate from the RF signal path.
Follow the PTT chain ↗Ready to Connect—Or Need a Hand?
Recent Additions
View All Updates →What’s New
Mobile Operations & POTA
W3UJ’s FTM-500DR/Comet VHF/UHF setup, FT-891/ATAS HF pairing, and the FT-891’s second role as a POTA radio.
Explore Mobile Operations →D-STAR at W3UJ
A separate digital-voice topic for the Kenwood TH-D75A and Elite 3.5 LCD ZUMspot, with a first-contact overview and troubleshooting.
Explore D-STAR →Four Clear Reference Destinations
Programs and drivers, test equipment and diagnostics, station equipment, and organizations now have clear entry points in Reference.
Open Reference →
Before you tune
Understand the conditions ↗Solar Weather & Band Outlook
Current UTC
Live clock · conditions timestamps below show when each source was updated.
Solar Activity SFI Solar flux / SFISolar radio emission at 10.7 cm, reported in solar flux units (sfu). It is an indicator of solar activity, not signal strength at your antenna.Reading the rangeSFI is a measured value, not a fixed 0–9 scale. Values are often roughly 60 to several hundred over a solar cycle; these are approximate context, not band-opening thresholds.At your stationHigher flux generally supports higher HF frequencies. Check the band outlook and actual reception; there is no single value that guarantees 10 m or 15 m is open.Click or tap ? to keep open. Escape or click outside to close.
—Higher solar flux generally supports higher HF frequencies. It does not guarantee an opening.
Waiting for NOAA dataK Index Planetary Kp · magnetic disturbance Planetary KpK describes disturbance at one magnetic observing station. Kp combines observations into a planetary estimate over a three-hour interval. This panel shows Kp, on the 0–9 scale.Reading the rangeBelow 5: below NOAA’s geomagnetic-storm threshold. 5–9: storm-level activity, with increasing severity. Below 5 does not guarantee good propagation.At your stationHigher disturbance can disrupt HF paths, particularly toward high latitudes. Compare more than one band before assuming a receiver fault.Click or tap ? to keep open. Escape or click outside to close.
—Lower means less geomagnetic disturbance. Kp 5 or above indicates storm-level activity.
Waiting for NOAA dataHF Blackout Status R scale HF radio-blackout scaleNOAA’s R scale describes solar-flare radio-blackout severity, mainly affecting the sunlit side of Earth.Reading the rangeR0: none reported here. R1: minor. R2: moderate. R3: strong. R4: severe. R5: extreme.At your stationNo reported event does not guarantee an open path. During a reported event, check NOAA’s HF absorption map and compare reception on another band.Click or tap ? to keep open. Escape or click outside to close.
—Solar-flare effects can weaken or interrupt HF on the sunlit side of Earth.
Waiting for NOAA dataEstimated HF Outlook Estimated HF band outlookCalculated Good, Fair, and Poor guidance for broad HF band groups. Daytime and nighttime refer to illumination along the radio path.Reading the rangeGood: relatively favorable. Fair: mixed or variable. Poor: more challenging. These are qualitative ratings, not measured probabilities or an open/closed switch.At your stationChoose a band to investigate, tune a real signal, and check audio readability or decoding. Local noise, antennas, mode, season, and the path still matter.Click or tap ? to keep open. Escape or click outside to close.
| Bands | Daytime | Nighttime |
|---|---|---|
| 80–40 m | — | — |
| 30–20 m | — | — |
| 17–15 m | — | — |
| 12–10 m | — | — |
Good: worth checking · Fair: variable · Poor: more challenging. These broad ratings do not declare a band open or closed.
Not rated here: 160 m, 60 m, and VHF/UHF. These are broad estimates, not measured local band conditions.
Waiting for band-outlook dataLoading conditions…
General outlook, not local reception or a path-specific forecast. Day and night depend on the locations along the path. Sources: NOAA SWPC · N0NBH / HamQSL.