MARS SDR Buildathon - Final Test Elmer Station

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Description of Final Test Elmer Station

This station is the final test where the builder discovers whether the RX receives. It consists of a signal generator or other signal source, a PC with Rocky installed, a soundcard, and a connection to a 50 ohm, 20m HF antenna.

Resources

Supplies

Item	Qty	Notes
9V battery	1
male-to-male stereo cable with 1/8" stereo plugs	1	(where builder used a Jack for IQ Output)
Antenna connector with clip leads	1	(with adaptors for bnc/uhf)

Tools

Item	Qty	Notes
20m Antenna	1	tuned to 14.06 MHz, Z=50 ohms

Instruments

Item	Qty	Notes
Signal Generator	1	capable of outputting/sweeping 14.06 MHZ test signal
Antenna Analyzer (optional)	1	(tuning antenna)
PC or Laptop with Rocky software loaded	1	(SDR)
USB Soundcard that accepts stereo inputs	1	(if PC has no stereo input)

Process

Setup

• Review the Rocky setup in the Enternal Connections Stage's Testing section.
• Connect sound card to PC
• Run Rocky on PC
• Set up Rocky for 14.0475 MHz center frequency (single LO)
• Set Rocky up for 48 kHz of 96 kHz, depending on sound card capabilities
• Set up/tune antenna for 20m

Test RX

• I/Q

  Connect RX's I/Q outputs to sound card's line-in jacks

• Antenna

  Connect RX's antenna cable to antenna

• Single Signal

  • Turn on Signal generator and generate 14.060 MHz signal near RX board
  • In Rocky, "Start Radio"
  • Connect RX to 9V battery
  • Look for strong signal near 14.060 MHz (with smaller and weakening image at 14.035 MHz)

• Sweep Signal (check inage rejection)

  Sweep the signal generator and observe the signal (and image) on the Rocky Spectrun. The stronger signal should move up and down the band as expected. If the signal and image approach each other or "fly away from" each other this is an indication that you are NOT getting independent and separate I and Q signals.

On the Air

• Antenna

  If the signal generator test works, connect the RX's antenna cable to the antenna

• Receive OTA Signals

  Look for RX having some effect on the Rocky Spectrum

• Tune

  Tune around for signals in the band

• Success

  Shake builder's hand and announce success to group

Pay Special Attention To:

• Image rejection.

  Elmers should study the image rejection materials to understand issues.

• Antenna Impedance

  The antenna used should have an impedance very close to 50 ohms. T he farther away from that ideal, the less the sensitivity of the RX.

• Mono Signals

  The most common problem at this stage is the failure to provide both left and right (I and Q) signals to the soundcard. Advise builder to be sure to read the caveat in the external connections stage concerning the top and ring assignments for the 20m RX (they are different than those documented in that stage for the 40 m units).

• Non- responsive to signal generator

  Send the builder to the troubleshooting station.

Build Stages Supported

• External Connections