435 Repeater Equipment

One frequently asked question is “what equipment do you use for the world famous 435?”  Such as:
“I’m a big fan of your repeater: I consider it to be a delightful mix of chaos, performance art, and some profoundly human conversations. Do you happen to have a repeater equipment list handy? Anything that can handle that much duty cycle is something I respect!”  –Peter
The 435 repeater is custom-built based on a GE Mastr design, but using modern components and condensed into a 2U rack shelf.  With the upgrades, we believe this is the best analog repeater currently available based on audio quality, receive sensitivity, squelch, efficiency and RF purity.   The build was suggested by Sam, commissioned by Roger Bly and designed and built by the “Rockstar.”
The RF power amp is a Henry which we modified to improve cooling and don’t run at full power.
Our world-class receive sensitivity results from using separate commercial 4-dipole receive and transmit antennas, an Angle Linear PHEMT preamp and the custom GE front end and squelch.  The receive antenna is at the top of the tower (about 100′) and the transmit antenna is mounted mid-tower (about 30′).

The Current 435 repeater rack, top to bottom:

  • Internet remote controlled AC Power switch.
  • Control / link radios.
  • Radio mount (unused)
  • Internet stack: router, firewall, switch, VoIP interfaces.
  • Samlex 1KW 120v AC power inverter for battery backup.
  • Linux computer; 8-core; VoIP interfaces, audio logging, analysis, finger printing.
  • Dual RF TX circulator.
  • 2m repeater based on a GE Mastr (Custom).
  • RLC Club Deluxe II 6-port repeater controller.
  • Samlex 100A 12V power supply.
  • Motorola timebase (unused).
  • 2m TX Henry RF amplifier.
  • 2m RX Preamp.
  • 2m duplexers and band pass cavities.
  • Batteries for inverter backup power.
435-repeater-rack

More Detail on the Custom GE Repeater

The core repeater is a rebuilt GE with RX helical resonator front-end.  The repeater is based on a GE Mastr II RX shelf converted to uMASTR II configuration with TX based on an Mastr Exec II PA frame gutted & rebuilt with a modern FET-brick and reworked crystals. We have a custom front panel, wiring harness and connectors compatible for our controller, finger printer, etc. The new TX FET-brick is cleaner and more efficient than the original class C PA; and should last for years at 100% duty cycle.

We stayed with the GE dual-hysteresis squelch and CTCSS filter. They’re amazing! CTCSS is completely removed, but recovered audio is otherwise unchanged. Thus a fairly flat audio is realized. The transmitter exciter includes its own special audio input for flat-below-4KHz TX audio. No limiter or clipper is present, or pre-emphasis; only the factory adjacent-channel splatter filter. Within the bandwidth limits of our 2-Meter channel, this is the ideal setup for high-fidelity audio.

435-GE-custom-2435-GE-custom-1

The Mastr Exec II TX PA frame on the back is a bit crusty on the outside, but it’s now beautiful inside with the new power brick and precision variable resistor for fine-tuned RF power adjustment.  The frame came from an Exec with 435 crystals. We cleaned it up a bit and added a heatsink fan before it was deployed on the hill September 2016.



Categories: Uncategorized

1 reply

  1. Re-built GE? I’m sure Gary Elmer would get a kick out of that. K6GE, The Best 435 Repeater Owner ever.

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