HP 8481D power sensorand 11708A reference attenuator.

[ytterligare]

Never owned any power meter, got one ( Agilent E4418B ) from one eBay source and a sensor from another eBay source last week.

The sensor arrived yesterday, and, besides the musty stench, I noticed that the reference attenuator mentioned in the user guide ( 11708A  30dB ) was missing.
Now, I believe this sensor was used years ago by a professional knowing what he's doing or at least I hope so, but what if the seller never used the attenuator to calibrate...?

Is it really that sensitive to require this attenuator ? English is not my first language and the manual says that the attenuator "SHOULD be connected" prior the calibration, which is confusing me...

Thanks for any opinion...
A.

P.S. the probe data :

HP 8481D -> 10 Mhz to 18 Ghz

100 pW to 100 µW ( -70 dBm to -20 dBm )

[xmo]

The calibrator in the power meter outputs a 50 MHz signal at a very accurate milliwatt level (0 dBm)

The 11708A 30 dB attenuator is used to calibrate the 'D' model sensors at 1 microwatt.

The 11708A 30 dB attenuator is a special model manufactured to be extremely accurate at 50 MHz.

You can use another high quality 30 dB attenuator - it just may not be quite as accurate.

[jjoonathan]

Yes, but could the 0dBm signal fry the sensor?

I have wondered that too. My guess would be no, and that the -20dBm limit is about keeping the diode(s) in the quadratic region rather than avoiding damage, but that's just a guess and not a basis for staking (price of power sensor) on it.

[Tony_G]

For the 8481D the max power is 100mW avg or pk so the 0dBm cal won't hurt it. However, as jjoonathan mentioned it is only accurate to 10μW and once it goes outside of the square-law region it is no longer accurate.

Those 11708A attenuators come up on eBay fairly often and they aren't matched to a given sensor so you can pick one up.

TonyG

[ytterligare]

Thank you, I was able to get an 11708A used, at a fair price.

Interesting info tho, make me use the sensor with more confidence.

Ciao
Andrea