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Thread: Any Los Angeles based Calibrators

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    Default Any Los Angeles based Calibrators

    Looking for recommendations for service monitor calibration services. Prefer not to ship them off to some far away land, so something local (Southern California) that can handle a Motorola 2670 and/or an IFR 1200 would be ideal? I googled, but when searching, looks like the companies that I find will calibrate anything. I'd prefer someplace with service monitor experience. I am not hung up on NIST traceable calibrations, but if the price is right...

    Thanks,
    Michael


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    NexTec Global (Zvika Golan).

    (310) 212-7770

    Not sure if he can do your 1200, but he can do your 2670 for sure. He is a General Dynamics specialist.

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    Thanks for the referral.

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    never understood the desire for NIST traceable calibration for typical two way use. Avionics guys do have to show a documentation path but never needed that in a land mobile context.

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    Quote Originally Posted by jry View Post
    never understood the desire for NIST traceable calibration for typical two way use. Avionics guys do have to show a documentation path but never needed that in a land mobile context.
    Accredited calibrations include the as found/as sent measured data which can be desired over just a calibration certificate which is common on non-accredited calibrations.

    One area of LMR that requires accredited calibrations is the CAP program for performance testing, but that's a very small group of test labs.

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    very rarely have seen the inbound outbound data in the reports.

    It may be included it to show what was done but even though I may have glanced at it never got much value out of it.

    Either the unit was in specification or not.

    Often on the R26XX series the IF filters alignment is not checked so you end up with ripple on the tracking gen function. Usually shows with the 5Mhz span. Both the RX and GEB IF filters should be checked and aligned to get the ripple down to an acceptable level.

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    Quote Originally Posted by d119 View Post
    NexTec Global (Zvika Golan).

    (310) 212-7770

    Not sure if he can do your 1200, but he can do your 2670 for sure. He is a General Dynamics specialist.
    +++1

    10MHz gps-disciplined i.e. fluke 910r is great when you can, but its still important to calibrate internal for when you need it.

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    Quote Originally Posted by jry View Post
    very rarely have seen the inbound outbound data in the reports.

    It may be included it to show what was done but even though I may have glanced at it never got much value out of it.

    Either the unit was in specification or not.
    This is the data you _must_ get in an accredited cal for something like a 3920 for it to actually be an accredited cal. The uncertainties are also important in calculating the test uncertainty if you are testing the extremes of performance.
    Attached Files Attached Files

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    Quote Originally Posted by duggerd View Post
    This is the data you _must_ get in an accredited cal for something like a 3920 for it to actually be an accredited cal. The uncertainties are also important in calculating the test uncertainty if you are testing the extremes of performance.
    Not quite sure what an "accredited " calibration ? Accredited by who ? Usually the manufacturers process is what is followed ...sometimes they include the worksheets and sometimes they do not ...depends on the model and manufacturer.

    When would you ever reference that data ? Like I said I have seen that with some units but I never referenced it the normal day to day operations and usage.

    The only time I would think to look at it is if a unit failed to meet spec and if that was handy so if what it was the last time.

    Most service monitors specifications are pretty loose and can vary by temperature and other conditions so unless you are the same conditions as the calibration was done may not be worth much as well.

    Typically the signal gen output specs are +- 2db on a decent unit. Part of that specification takes into account variances in ambient temp, warm up and voltage

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    Quote Originally Posted by jry View Post
    Not quite sure what an "accredited " calibration ? Accredited by who ? Usually the manufacturers process is what is followed ...sometimes they include the worksheets and sometimes they do not ...depends on the model and manufacturer.

    When would you ever reference that data ? Like I said I have seen that with some units but I never referenced it the normal day to day operations and usage.

    The only time I would think to look at it is if a unit failed to meet spec and if that was handy so if what it was the last time.

    Most service monitors specifications are pretty loose and can vary by temperature and other conditions so unless you are the same conditions as the calibration was done may not be worth much as well.

    Typically the signal gen output specs are +- 2db on a decent unit. Part of that specification takes into account variances in ambient temp, warm up and voltage
    There are two concepts here, traceable calibrations and accredited calibrations. NIST traceable means that the all the equipment in the chain that the unit was calibrated with were all derived off a NIST master reference source. Accredited calibrations are additional requirements put onto a traceable chain of standards such that you have to report the level of uncertainty that the calibration could be off.

    With just a "NIST Traceable" calibration, the piece of equipment could be calibrated directly against a NIST master source, or that piece of equipment could be calibrated by a transfer standard that was calibrated by another transfer standard...repeat 40 times...that was calibrated against a NIST master source. Therefore the accuracy of what you were calibrating the unit from could be anything. You have no way of knowing what of those two options actually happened.

    With an accredited calibration, the calibration lab would be accredited by NVLAP or ANAB or A2LA to ISO 17025:2005 or ANSI Z540.3, and would produce calibration reports that conform to the ANSI or ISO accreditation requirements (having test data and measurement uncertainties among a stack of other requirements). Therefore when you see the measurement uncertainty is 10dB, you would know that the calibration is meaningless.

    Service monitors are a all-in-one tool and don't have the highest accuracy and precision, but as someone who has to produce accredited test reports at a test lab for P25 equipment to TIA-102.CAAA-E/TIA-102.CAAB-D I've had to reference these uncertainties many times to be able to call something pass or fail.

    For most people using service monitors to auto-tune radios it won't _really_ matter, but it is a good indicator of calibration quality rather than a "NIST traceable" calibration report that isn't worth the paper it is printed on.

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    Ya, I have both a GPSDO and OCXO for my test equipment, but a good calibration, especially when its probably been 5 years or more, seems prudent. So far, Zvika has been a pleasure to deal with.

    Quote Originally Posted by PSEhub View Post
    +++1

    10MHz gps-disciplined i.e. fluke 910r is great when you can, but its still important to calibrate internal for when you need it.

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    So typically you would refer to these as calibration provided by Brand X accredited facilities ( much the same way that you obtain a college degree from an accredited university )

    The cal itself is not accredited but the provider is. Providing the checklist may be part of maintaining their accreditation standards depending on who they used for this.

    Accreditation implies that there is a third party oversight of the practices and procedures to maintain quality to a minimum level

    I agree completely on the NIST for land mobile ...completely worthless in a land mobile context since most of the equipment
    a. is used in the field and bounced around all the time and used in unstable environments even on the bench
    b. never had that great of a tolerance in the first place ( some of the good stuff is still +- 4db on measurements )

    Calibration really has its value in verifying full functionality within the manufacturers spec ....two years would be my threshold especially for field equipment.