It seems a good percentage of young PMEL techs have a bad habit of limiting equipment IAW the K-procedure STEP and not IAW the table 1 specifications. Example: "Third Order Intermodulation not cal'd at 8.4 GHz." 8.4 GHz was one of three frequencies called for - the problem was the unit was spec'd for TOI from 2-12.4 GHz for this 8.4 check point. THis would not be a QR failure since it passed at 8 GHz but it was a PR failure as the technician could not explain any error and just carried over the previous limitation. Moral: Be VERY, VERY careful when using the word "AT" in a limitation.
A K1 example that was a QR failure was a 3400A limited as "NOt cal'd at 10 MHz". When tested at 9 MHz, it failed. A proper limitation would have been, "Not Cal'd above 5 MHz".
Good examples.
They should also be in terms that the user can relate to or see in their TO/commercial data. This is a bad one I had recently.
"Harmonics of center frequencies greater than 40 MHz are less than 25 dBc" - or very close to that. As a tech we understand where they were going but most people don't and its completely unrelated to table 1 wording.
That "dBc" is a real tough one to phrase. It technicially means "dB below carrier". As such, there is no such thing as MINUS dBc since it is relative. Other mistatements are "< 40 dBc" which would mean between 0 and 39 dB below carrier. "> 40 dBc" would be the more proper statement.
Adding to the confusion is every method (greater than, less than, minus, plus and combinations of the these) of stating dBc are found in K-procedures, T.O.s and OEM manuals. This is aa area that NIST and AFMETCAL need to clarify for the industry. As QA, I suggested the technicians use the phrasing found in the calibration procedure to determine the proper phrasing of limitations in these areas.
Until recently when I asked myself what does it really mean I wouldn't have argued but it does not actually mean below carrier. Its deciBel related to the Carrier.
I'll quote some website
"Another common usage is dBc, which is essentially a relative term with a variable reference, like dB alone. It is usually taken to mean "dB referenced to a carrier level" and is most commonly seen in radio receiver specifications regarding spurious signals or images. For example, "Spurious signals shall not exceed -50 dBc" means that spurious signals will always be at least 50 dB less than some specified carrier level present (which could mean "50 dB less than the desired signal").
"
I always thought it could mean either but I think that was because of training or a CDC typo that said below.
like dB sound - its all relative. dBm is an actual value - sorta it represents a power level.
I'm just a rookie. We can let flewdacoup the expert share his 2 cents though.
Where I come from we use robogrips on 3.5 connectors*
No we don't but it has been alluded to that we do.
man i miss AF calibration lol