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GopherTrunk Outdoor Base Station Build
This is the flagship build: a wideband base antenna up on a mast, a low-loss feedline run indoors, proper grounding and a lightning arrestor, and a mast-mounted LNA feeding a PC or Pi running GopherTrunk. Height and low loss are what turn a hobby setup into a station that hears the whole system. Budget about $300–450, mostly feedline and mounting.
Key takeaways Antenna: outdoor wideband discone (~$70). Get it high: mast + eave/wall bracket (~$60). Low-loss feedline: LMR-400 (~$70 for 50 ft). Safety: grounding kit + coax lightning arrestor (~$45). Recover feedline loss: mast-mounted LNA (~$30). Indoors: a PC or Pi + dongle. No build decodes encryption.
The complete parts list
| # | Item | Why | Pick | Approx $ |
|---|---|---|---|---|
| 1 | Outdoor base antenna | The whole point — height + wideband coverage | Discone antenna | ~$70 |
| 2 | Antenna mast | Raises the antenna above the roofline | Push-up / steel mast | ~$35 |
| 3 | Eave / wall bracket | Anchors the mast to the structure | Eave mount bracket | ~$25 |
| 4 | Low-loss feedline | Keeps signal on the wire at UHF | LMR-400, 50 ft, N-male | ~$70 |
| 5 | Coax lightning arrestor | Protects gear + home at the entry point | N-type surge arrestor | ~$30 |
| 6 | Grounding kit | Bonds mast + coax shield to ground | Ground clamp / bonding kit | ~$15 |
| 7 | Mast-mounted LNA | Recovers feedline loss before it happens | RTL-SDR Blog wideband LNA | ~$30 |
| 8 | SDR dongle | Receives the radio | RTL-SDR Blog V4 (bias tee for the LNA) | ~$35 |
| 9 | Indoor computer | Runs GopherTrunk | A PC or Pi | $0–80 |
| + | Adapters / weatherproofing | Join it all, keep water out | SMA kit + self-amalgamating tape | ~$20 |
Running total: ~$330–410, dominated by feedline length and mounting. A longer coax run or a taller mast pushes it toward the top of the range.
The key picks
Wideband discone antenna
around $70
Covers roughly 25–3000 MHz — one outdoor antenna that hears VHF, UHF, and the 700/800 MHz trunked bands. Mounted high on a mast, it is the single biggest upgrade you can make to reception.
Discone on Amazon →LMR-400 low-loss feedline (50 ft)
around $70
Ultra-low-loss 50-ohm coax with N-male ends. At 700/800 MHz, thin cable bleeds signal fast over a long run — LMR-400 is what makes a rooftop-to-basement run viable.
LMR-400 on Amazon →RTL-SDR Blog wideband LNA
around $30
Low-noise amplifier, bias-tee powered up the coax. Mount it at the antenna so it lifts the signal before the feedline attenuates it — the correct way to fight loss on a long run.
LNA on Amazon →Why height and low loss win
A base station beats a desk setup for two physical reasons: the antenna is higher (more line of sight to distant sites) and the RF chain is engineered for low loss at UHF. Both are things no receiver can fix downstream.
- Get the antenna above the roofline. A discone on a mast anchored by an eave or wall bracket clears obstructions and adds range. Height is free signal — spend effort here first. See the mast and mounting guide.
- Run low-loss feedline. Coax loss climbs with frequency, and trunked systems sit right where thin cable bleeds worst. Use LMR-400 for the run from roof to receiver, keep it as short as the layout allows, and weatherproof every outdoor junction with self-amalgamating tape.
- Amplify at the antenna, not the desk. A mast-mounted LNA recovers feedline loss because it lifts the signal before the coax attenuates it. Power it up the coax with the dongle’s bias tee — the RTL-SDR Blog V4 has one built in. Do not add gain if strong local signals already threaten overload.
Safety — not optional on a rooftop
Ground it and fuse it. Any permanently mounted outdoor antenna needs a grounding kit bonding the mast and coax shield to ground, and a coax lightning/surge arrestor at the point the feedline enters the building. This protects your equipment and your home from static buildup and nearby strikes. Follow local electrical code, and if you are not comfortable with the install, hire a pro. This is the one part of the build you do not skip or cheap out on.
Feed a PC or a Pi indoors
The base station is the RF front end; the computer is the decoder. Run the feedline to either a PC you own or a dedicated Raspberry Pi near the entry point. A Pi is popular here: place it right where the coax comes in to keep the run short, and run GopherTrunk headless 24/7 through its web console. Want to cover several sites from this one antenna? Split it into a multi-dongle pool — mind the overload a shared feed can cause.
Where to buy
The heart of the build is the discone antenna (~$70) and a run of LMR-400 feedline (~$70), with a mast, bracket, grounding kit, arrestor, and a mast-mounted LNA completing the front end.
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Bottom line
A high discone + low-loss LMR-400 + a mast-mounted LNA, grounded and arrestor-protected, feeding a PC or Pi is the best-hearing GopherTrunk build there is — about $300–450, mostly feedline and mounting. Spend on height and low loss first; they are what a receiver cannot fix. And remember: more range still means more clear traffic, never encrypted. Compare the other setups on the build-lists hub.
Frequently asked questions
What do I need for a rooftop GopherTrunk base station?
An outdoor base antenna (a wideband discone), a mast and a wall or eave bracket to mount it high, a low-loss LMR-400 feedline run indoors, a grounding kit and coax lightning arrestor for safety, a mast-mounted LNA to recover feedline loss, and a PC or Raspberry Pi indoors running GopherTrunk. Budget about $300–450 depending on feedline length.
Why LMR-400 instead of thin coax for a base station?
Coax loss climbs steeply with frequency, and trunked systems sit at 700/800 MHz where thin RG58 or RG316 bleeds signal badly over a long run. Low-loss LMR-400 keeps most of the signal on the wire from a rooftop antenna to an indoor receiver. On any run over about 25 feet at UHF, the cable choice matters as much as the antenna.
Do I really need a lightning arrestor and grounding?
For any permanently mounted outdoor antenna, yes. A coax lightning/surge arrestor at the entry point and a proper ground bond protect your equipment and, more importantly, your home from static discharge and nearby strikes. It is inexpensive insurance that is not optional on a rooftop install — follow local electrical code.
Where does the LNA go in a base station build?
At the antenna, at the top of the feedline — a mast-mounted LNA amplifies the signal before the coax attenuates it, recovering the feedline loss you cannot avoid on a long run. Power it up the coax with the dongle’s bias tee. Do not add gain if strong local signals already threaten to overload the front end.
Can one outdoor antenna feed both a scanner and GopherTrunk?
Yes, through a splitter, but expect some loss and watch for overload — a strong local signal in a shared feed degrades every receiver on it. For a dedicated GopherTrunk base station, running the antenna straight to one receiver gives the best results. Splitting is covered in the multi-dongle build.
What indoor computer does the base station feed?
Either a PC you own or a dedicated Raspberry Pi. The base station is the RF front end; the computer is the decoder. A Pi is popular because it can sit near the feedline entry point, keeping the coax run short and letting you run GopherTrunk headless 24/7.
Will a base station hear encrypted channels?
No — height and gain improve range and signal quality, but no antenna or amplifier can decode AES-encrypted talkgroups. A base station dramatically improves what you hear in the clear, which in most areas is plenty of dispatch and nearly all fire and EMS.