307 FREQ ACC Transfer oscillator pretuned DAC out of range. The transfer oscillator pretune procedure attempts to find pretuned DAC values by programming the PLL to 25 different frequencies and incrementing the transfer oscillator pretune DAC until XFRSENSE changes polarity. ERR 307 is set if the DAC is set to 255 (maximum) before XFRSENSE changes polarity.

308 FREQ ACC Offset oscillator pretune DAC not within prescribed limits at low frequency. The offset oscillator pretune DAC is set to provide a frequency less than 189 MHz while the PLL is programmed for 189 MHz. ERR 308 is set if XFRSENSE is greater than i-5 V (it should be at the negative rail).

309 FREQ ACC Offset oscillator pretune DAC not within prescribed limits at high frequency. The offset oscillator pretune DAC is set to provide a frequency less than 294 MHz while the PLL is programmed for 204 MHz. ERR 309 is set if XFRSENSE is greater than +5 V (it should be at the negative rail).

310 FREq ACC Main roller pretune DAC set to 255. The main roller pretune DAC is set to 5, causing MAINSENSE to go to the positive rail. The DAC is incremented until MAINSENSE changes polarity. ERR 310 is set if the DAC is set to 255 before MAINSENSE changes to a negative polarity.

311 FREQ ACC Main roller pretune DAC set to 255. The main roller pretune DAC is set to 5, causing MAINSENSE to go to the positive rail. The DAC is incremented until MAINSENSE changes polarity. ERR 311 is set if the DAC is set to 255 before MAINSENSE changes to a negative polarity.

312 FREQ ACC Unable to adjust MAINSENSE to 0 volts using the fine adjust DAC. The coarse adjust and fine adjust DAC are used together to set MAINSENSE to 0 volts with the loop opened. ERR 312 is set if the fine adjust DAC cannot bring MAINSENSE to 0 volts.

313 FREQ ACC Error in LO synthesis algorithm. ERR 313 is set if a combination of Sampler oscillator and roller oscillator frequencies could not be found to correspond to the required YTO start frequency. Contact the factory.

314 FREQ ACC Indicates problems in the span calibration. Troubleshoot any unlocks before attempting to troubleshoot span calibration problems, because the loops must all lock in order to perform the calibration. If LO spans greater than 1 MHz are correct, check A14U114B , A14U115A, A14U116, or A14QlOl. This error message appears when the main roller oscillator sweep sensitivity is 0. A sweep ramp is injected into the locked main roller loop which should generate a negative-going ramp on MAINSENSE. ERR 314 is set if the slope of this ramp is 0. This is an indication of an unlocked main roller loop or lack of a sweep ramp.

General Troubleshooting 6-19