Repeater Trustee Workshop

Transcription

1 Repeater Trustee Workshop Presented on Behalf of the Magnolia Intertie By: Thomas Gandy (N5WDG)

2 Repeater Design Considerations Hardware New vs Used Site Selection Critical Components of an RF Transmission System Antennas Feed lines Duplexers/Diplexers Connectors Receivers Sensitivity Testing Power Amplifiers Interference Mitigation and Testing Lightening Protection & Grounding Maintenance and Record Keeping Resources Q&A

3 Hardware New vs Used Used Pros Low Cost Readily Available Higher Quality than Amateur Grade Cons Frequency/Band Specific Complicated Programming Interfaces and software Reliability Issues New Pros Reliability Feature Rich Factory Technical Support Software Programmable Cons Costly Not as easily Repairable

4 Available Antenna Space To Lease or Not to Lease Road Building/Site Access Rooftop vs Tower Environmental Control & HVAC Security Back Up Power Adequate Grounding RF Noise Transmission Line Site Considerations

5 The RF Transmission System Antenna Duplexers Main Feed Line Connectors Jumpers RF Environment

6 Repeater Receiver Sensitivity Testing Repeater RF Checkout 12dB SINAD Receiver Direct Duplexer Transmitter Power with out Duplexer Iso T Load Iso T Load with TX Iso T and Antenna Iso T Antenna with TX Transmitter Direct 38 Watts 45.8 Duplexer Watts ##### db Reflected Power 0.5 Watts Performance Calculations Loss Through Duplexer Iso T Isolation In Cabinet Desense Environmental Degredation Antenna Duplex Desense Effective Sensitivity 0 TX Duplexer Loss ####### db SWR ####### :1

7 Repeater Receiver Sensitivity Testing Repeater RF Checkout 12dB SINAD Receiver Direct Duplexer Forward/Reverse Power into Antenna Iso T Load Iso T Load with TX Iso T and Antenna Iso T Antenna with TX Type equation here. Transmitter Direct 38 Watts 45.8 Duplexer 23 Watts db Reflected Power 0.5 Watts Performance Calculations Loss Through Duplexer Iso T Isolation In Cabinet Desense Environmental Degredation Antenna Duplex Desense Effective Sensitivity 0 TX Duplexer Loss 2.18 db SWR 1.35 :1

8 Repeater Receiver Sensitivity Testing Repeater RF Checkout 12dB SINAD Receiver Direct Duplexer Direct Receiver Sensitivity Iso T Load Iso T Load with TX Iso T and Antenna Iso T Antenna with TX Transmitter Direct 38 Watts 45.8 Duplexer 23 Watts db Reflected Power 0.5 Watts Performance Calculations Loss Through Duplexer Iso T Isolation In Cabinet Desense Environmental Degredation Antenna Duplex Desense Effective Sensitivity ####### db ####### db ####### TX Duplexer Loss 2.18 db SWR 1.35 :1

9 Repeater Receiver Sensitivity Testing Repeater RF Checkout 12dB SINAD Receiver Direct Duplexer Receiver Sensitivity Through Duplexers into LOAD Transmit on/off Iso T Load Iso T Load with TX Iso T and Antenna Iso T Antenna with TX Transmitter Direct 38 Watts 45.8 Duplexer 23 Watts db Reflected Power 0.5 Watts Performance Calculations Loss Through Duplexer Iso T Isolation In Cabinet Desense Environmental Degredation Antenna Duplex Desense Effective Sensitivity 1.9 db 45.6 db 1.3 db 75.3 db TX Duplexer Loss 2.18 db SWR 1.35 :1

10 Repeater Receiver Sensitivity Testing Repeater RF Checkout 12dB SINAD Receiver Direct Duplexer Receiver Sensitivity Through Duplexers into Antenna Transmitter on/off Iso T Load Iso T Load with TX Iso T and Antenna Iso T Antenna with TX Transmitter Direct 38 Watts 45.8 Duplexer 23 Watts db Reflected Power 0.5 Watts Performance Calculations Loss Through Duplexer Iso T Isolation In Cabinet Desense Environmental Degredation Antenna Duplex Desense Effective Sensitivity 1.9 db 45.6 db 1.3 db 3.9 db 13.4 db TX Duplexer Loss 2.18 db SWR 1.35 :1

11 RF Power Amplifiers Path Balance: Most 2m and 70cm link budgets are UPLINK limited. Don t out talk your receivers ears. 3dB Rule Duty Cycle: Choose a HIGH QUALITY continuous duty PA with adequate mechanical or convection cooling. Power Supply: Determine the maximum current required for the PA output and size the power supply accordingly. Jumpers: Use HIGH QUALITY (RG214/U or FSJ4 ½ Superflex) jumpers between the amplifier, duplexer, and main feed line. Duplexers: The more TX power the more critical the duplex isolation becomes to avoid RF desense. This IS a repeater Amp THIS is NOT a repeater Amp

12 Interference & Noise Radio Interference : Any signal that causes the disruption, degradation, or loss of reception of the information carrying signal or wave. Site Interference Co Sited Transmitters Faulty Grounding or Shields Hardware Failure or Configuration Loose Connectors (N Type only!!!) Faulty Antennas High SWR (>2:1) Inadequate Filtering or Isolation Low Quality Receiver/Transmitter External Site Interference Adjacent or Co Channel Transmitters Jammers Skip Electrical Distribution Systems & Transformers User Noise & Interference Vehicle Noise Wall warts and Power Supplies Off Frequency Receiver/Transmitter Undersized Power source Location

13 Lightening Protection & Grounding AC Ground: Insure that ALL AC line grounding plugs are properly tied to the AC ground. Feed Line Protection: Use DC Block (best) or gas discharge line protection with minimum 600V (gas) or 500mV (DC block) rating. Coax Connectors: Use N Type coax fittings (DIN Connectors are best) NO ADAPTERS! Avoid using Nickel, Stainless or ferrite within the signal path. Use gold center pins and restrict all conductors to copper. Grounding: Bolt all protection device wires to the main ground bar (MGB). Crimping and screw terminals can corrode and form a resistive connection over time. Equipment Ground: Bolt all equipment grounding terminals to a single cabinet ground that connects to the MGB. DC Block Arrestor DC Pass Gas Discharge Arrestor Typical Equipment Grounding

14 Maintenance & Record Keeping Site Access: Assign 2 members of the club or association with site directions, access/keys and control codes to the repeater. Technical Binder: Gather all equipment materials and keep them in a SINGLE binder or shared drive location. Station Log: Keep a station log and document each site visit and any maintenance or testing activity that was performed. Station Identification: Place a STATION IDENTIFICATION SIGN on all equipment displaying the call sign and contact information for the repeater custodian and a back up.

15 Resources & Acknowledgements Repeater Builder Technical Information Page TM builder.com Batwings Laboratory Polyphaser Lightening Protection Southeastern Repeater Association Comscope (Decibel Products) Bird Industries (RFCalc) Arcom Repeater Controllers