# Re: B200 clock calibration

**URL:** <https://www.ruby-forum.com/t/re-b200-clock-calibration/241157>\
**Category:** GNU Radio\
**Created:** [May 15, 2014, 11:49am UTC](https://www.ruby-forum.com/t/re-b200-clock-calibration/241157 "2014-05-15T11:49:44Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![musicdenotation](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/m/ea666f/32.png) [@musicdenotation](https://www.ruby-forum.com/u/musicdenotation)\
**Post date:** [May 15, 2014, 11:49am UTC](https://www.ruby-forum.com/t/re-b200-clock-calibration/241157/1 "2014-05-15T11:49:44Z")

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Hi, In case we use on-board oscillator , how is ADF4001 configured? Does  
CP (pin20) output affect the VCXO\_Tune ? Is it possible to control this  
chip directly from the command line?

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**Author:** ![rlorimor](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/r/96bed5/32.png) [@rlorimor](https://www.ruby-forum.com/u/rlorimor)\
**Post date:** [May 15, 2014, 5:18pm UTC](https://www.ruby-forum.com/t/re-b200-clock-calibration/241157/2 "2014-05-15T17:18:55Z")

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The ADF4001’s output charge pump is tristated when not locking to an  
external reference, and a resistor divider holds the VCTCXO’s tuning  
input  
at 1/2 Vcc. The B200 hardware can use the AD9361’s low-speed DAC to  
drive  
the VCTCXO’s tuning input via AUXDAC1 if R118 is populated; however,  
this  
functionality is not supported by the B200 UHD driver.

–n