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GopherTrunk Multi-Dongle Build
GopherTrunk can drive a whole pool of SDRs at once, so one instance covers multiple sites or control channels simultaneously. This build is the hardware for that: a powered USB hub, several dongles, an antenna feed for each, and enough compute to keep up. GopherTrunk is free; the pool is about $180–260 depending on dongle count.
Key takeaways Foundation: a quality powered USB hub (~$35) — several dongles overdraw an unpowered one. Receivers: 2–4 RTL-SDRs (~$35 each), each a unique serial and role. Antennas: one per band, or one feed + a splitter. Compute: a capable PC or Pi 5. Watch overload on shared feeds. No build decodes encryption.
The complete parts list
| # | Item | Why | Pick | Approx $ |
|---|---|---|---|---|
| 1 | Powered USB hub | Clean, stable power for every dongle | 10-port powered USB 3.0 hub | ~$35 |
| 2 | SDR dongles (×2–4) | One per site/control channel | RTL-SDR Blog V4 / NESDR | ~$35 each |
| 3 | Antennas | Feed each band you cover | Discone / dipole per band | ~$25–70 |
| 4 | Antenna splitter (if sharing) | Split one feed to several dongles | 2-way SMA splitter | ~$15 |
| 5 | SMA adapters / jumpers | Join hub, splitter, and dongles | SMA adapter kit + pigtails | ~$20 |
| 6 | Capable computer | Decodes the whole pool | A PC or Pi 5 | $0–80 |
| + | Broadcast notch filter (optional) | Protect a shared feed from overload | FM block filter | ~$25 |
| + | Wideband Airspy (alternative) | Channelize several channels from one capture | Airspy | ~$170 |
Running total (hub + two dongles + shared antenna): ~$180. Each extra dongle adds ~$35; covering more bands adds antennas. A wideband Airspy is an alternative strategy, not an add-on — see below.
The key picks
Powered USB 3.0 hub (10-port)
around $35
Its own 60W supply and per-port switches give every dongle clean, stable power and physical spacing — so the host never has to source all that current and the sticks run cooler and quieter. The part a multi-dongle build is built on.
Powered hub on Amazon →NooElec NESDR SMArt v5
around $35 each
Its R820T2/R860 tuner is always in stock, so you can re-order matching dongles for years. The right pick when you are buying several and want them identical and re-orderable.
NESDR on Amazon →Airspy (wideband)
around $170
Grabs up to ~10 MHz at once so GopherTrunk can channelize several control channels from one capture — one receiver doing the job of several dongles, when the channels fall within one window.
Search Airspy on Amazon →Two ways to cover more than one channel
There are two strategies, and many builds combine them — the full treatment is in the multi-dongle and wideband setup guide:
- A pool of narrow dongles. Each RTL-SDR tunes its own frequency — ideal when a system’s sites or control channels are spread far across a band. Assign a dongle per site, or one to the control channel and another to follow voice.
- One wideband receiver, channelized. A single Airspy captures up to ~10 MHz and GopherTrunk channelizes it, extracting several control channels from that one stream in software — ideal when the channels you want fall inside one window.
| Approach | Best when | Hardware |
|---|---|---|
| Dongle pool | Sites/channels spread across a band | Several RTL-SDRs + powered hub |
| Wideband channelize | Channels within ~10 MHz | One Airspy |
| Hybrid | Big multi-site systems | Airspy + dongles for the outliers |
Serials, roles, and power
Set unique serials first. Fresh RTL-SDRs often share the same default serial, so the OS enumerates them in an unpredictable order. Use
rtl_eepromto give each a unique serial, then refer to each by serial in GopherTrunk. Now “the control dongle” is always the same physical stick, and you assign roles — control tracking, voice following, wideband capture — that GopherTrunk coordinates so grants are never missed.
The powered hub is not optional. Several dongles draw more current than an unpowered hub — or a bare Raspberry Pi — can safely source, and they run warm. A good powered hub gives each stick clean power and spacing so they stay cool and quiet.
Overload on shared feeds
A strong local signal poisons every channel in a shared capture. When you split one antenna across dongles, or channelize many signals out of one wideband Airspy stream, an overloading broadcast FM, pager, or AM transmitter degrades all of them at once. Put a broadcast notch or bandpass filter ahead of the split, keep gain conservative on wideband captures, and check the noise floor before blaming the decoder.
For channels on very different bands, separate antennas often beat one shared feed. When you do share, a 2-way splitter and a filter keep the pool healthy.
Where to buy
Build on a powered USB hub (~$35), standardize on identical NESDR SMArt v5 dongles (~$35 each) so you can re-order them, and feed them from antennas per band or one shared feed and a splitter. Prefer one wideband receiver? Step up to an Airspy instead.
As an Amazon Associate, GopherTrunk earns from qualifying purchases — at no extra cost to you. It never changes what we recommend.
Bottom line
A powered hub + several dongles with unique serials + a capable computer lets one GopherTrunk instance cover multiple sites or control channels at once — about $180–260 depending on dongle count. Feed the pool from a powered hub, filter strong locals before any split, and consider a wideband Airspy if your channels sit in one window. More receivers hear more of the clear system — never encryption. Compare the other setups on the build-lists hub.
Frequently asked questions
What do I need for a multi-dongle GopherTrunk build?
A powered (active) USB hub, two or more RTL-SDR dongles, an antenna feed for each (or one antenna and a splitter), a computer or strong SBC with enough USB and CPU, and the usual adapters. Budget about $180–260 depending on how many dongles you run. GopherTrunk coordinates the whole pool by serial and role.
Why do I need a powered USB hub for multiple dongles?
Several RTL-SDRs draw more current than an unpowered hub or a Raspberry Pi can safely supply, and they run warm. A quality powered (active) USB hub gives each dongle clean, stable power and physical spacing so they run cooler and couple less noise into each other. It is the foundation of a reliable multi-dongle build.
How do I tell identical dongles apart in GopherTrunk?
Give each RTL-SDR a unique serial with rtl_eeprom, then reference dongles by serial in GopherTrunk’s config. Without unique serials the OS enumerates identical dongles in an unpredictable order, so setting serials is the first step in any multi-dongle build — then ‘the control dongle’ is always the same physical stick.
Should I use several dongles or one wideband Airspy?
It depends on how your channels are spread. A pool of narrow dongles is best when a system’s sites or control channels are far apart across a band — one dongle each. A single wideband Airspy is better when the channels you want fall within one ~10 MHz window, because GopherTrunk can channelize several from that one capture.
Can I share one antenna across multiple dongles?
Yes, with a splitter, but expect some loss and watch for overload — a strong local signal in a shared feed degrades every dongle on it. Filter strong locals ahead of the split and keep gain conservative. For channels on very different bands, separate antennas often work better than one shared feed.
Do I need more computer for a multi-dongle build?
Somewhat. Each dongle adds a decode workload, so a large pool wants a capable host — a strong laptop, a desktop, or a Pi 5 for a modest pool. A single Pi 5 handles a few dongles comfortably; a big multi-site pool is happier on a desktop or a machine with plenty of USB bandwidth and cores.
Will running more dongles let me hear encrypted channels?
No. More receivers means more channels and sites covered at once, but no number of dongles can decode AES-encrypted talkgroups. A multi-dongle build simply hears more of what is transmitted in the clear, across more of the system, at the same time.