I want to make my own repeater

UHF and above operations
1

I want to make my own UHF repeater, but I don’t have the money for a 2,000 dollar rig. if anyone has any suggestions they would be much appreciated

2

@KF8GDM This is what google says on how to make a ham radio repeater. (it is google so take it with a grain of salt but it may give you a few pointers)

1. The Ultra-Budget Route: The “Dual Mobile” Setup ($150 - $250)

The cheapest way to get on the air is linking two mobile radios (or even HTs, though mobiles are highly preferred for duty cycle). One radio acts as the receiver (RX), and the other acts as the transmitter (TX).

  • The Radios: Look for used, older commercial mobile radios on eBay like the Motorola Radius M120, SM50, or Maxtrac. You can often find these for $30–$50 each. Make sure they cover the amateur 70cm band (440-450 MHz). Alternatively, some guys use cheap Chinese mobiles (like Retevis or QYT), but commercial surplus has much better filtering.
  • The Controller: You need a way to link them so that when the RX radio hears a signal, it keys up the TX radio and passes the audio.
    • No-budget option: A simple cross-band relay cable or a cheap Surecom SR-112 / SR-628 controller ($30–$50) will handle basic COS (Carrier Operated Switch) linking and station IDing.
    • Better option: An Argent Data ADS-SR1 or a Raspberry Pi running AllStarLink/HamVoIP with a simple USB radio interface (like a Masters Communications RA-series board). This gives you incredible control and internet linking for under $100.

2. The Cleanest Route: Commercial Surplus ($200 - $400)

Instead of linking two separate radios, buy a retired commercial repeater. Because commercial systems are upgrading to digital (P25/DMR), older analog repeaters are being sold for pennies on the dollar.

  • Motorola GR1225 / R1225: These are desktop repeaters that output about 10–45 watts. You can frequently find them on eBay or at hamfests for $150–$250. They are a self-contained RX/TX unit.
  • BridgeCom BCR-40U: Keep an eye out for used ones. They are modern, rugged, and built specifically for continuous duty.
  • Vertex Standard VXR-7000 or VXR-9000: Excellent, rugged UHF repeaters that often pop up used for under $300.
  • Note on Commercial Gear: You will need the programming software and a programming cable. Check online forums (like Repeater-Builder) to ensure you can actually program the specific model to ham frequencies before buying.

3. The Unavoidable Cost: The Duplexer ($80 - $150)

If you want to use one antenna for both transmitting and receiving (which you do, to avoid massive desense and desensitization issues), you must buy a duplexer.

  • On UHF, you can get away with a cheap, small 6-cavity mobile notch duplexer (often called a “Chinese mobile duplexer” branded by Celwave clones, SainSonic, or JeonSheng) for around $80–$100 on Amazon or eBay.
  • Crucial Step: These must be tuned precisely to your specific RX and TX frequency pair using a Vector Network Analyzer (VNA). If you don’t own a NanoVNA or know how to use one, buy from a vendor on eBay who offers free tuning to your frequencies before shipping.

4. Power Supply and Antenna ($100 - $150)

  • Power Supply: Don’t skimp here. A solid 12V 20A–30A switching power supply (like a Mean Well or a cheap Lepai/Megawatt) will cost $30–$50.
  • Antenna: A solid fiberglass omnidirectional antenna like the Tram 1481 or Diamond X50A ($80–$100) works great for UHF.
  • Coax: Use high-quality coax. Because UHF has high signal loss, use at least LMR-400 or generic equivalent for short runs. Do not use cheap RG-58.

Summary Checklist for a $350 Setup:

  1. Two used Motorola Maxtrac/Radius UHF Mobiles ($80 total)
  2. Surecom SR-628 Controller ($50)
  3. 6-Cavity UHF Mobile Duplexer (Pre-tuned) ($90)
  4. Mean Well 12V 29A Power Supply ($35)
  5. Tram 1481 UHF Antenna + 50ft LMR-400 ($100)