Forums › BB Series Discussions › Input power safety.
- This topic has 3 replies, 4 voices, and was last updated 6 years, 12 months ago by Justin Crooks.
Ivan IonovParticipantIvan Ionov March 1, 2016 at 2:55 am
I see in the manual – Do not exceed +20 dBm or damage may occur.
Is that true for any combination of preamp/attenuator settings?
Or BB60C input has best protection with +20dBm reference level (attenuators on, preamp off) and weakest protection with -60dBm reference level (attenuators off, preamp on at maximum gain).
Does it make any difference, whether strong signal is within my span range of outside my region?
Can I safely turn gain at max and inspect weak signal in one range, when I have some strong signal (<=20dBm) outside my range of interest?
For example, I attach an antenna and try to look at weak signal in 1200MHz range +-20MHz span, so I switch reference level to -60dBm (preamp at max). Can some strong signal outside my range (for example somebody’s cellphone at 900MHz accidentally makes +16dBm at my antenna) make damage to preamp in this case? Can this strong signal produce clipping in preamp and distort my weak signal?
AndrewModeratorAndrew March 1, 2016 at 9:23 am
Yes, that is generally true (do not exceed +20 dBm input) for any combination of preamp/atten settings. It is recommended to stay under the reference level though if you can.
Also, a strong signal within the IF band but not within your visible span can produce IF overload.
The biggest concern is the input into the preamp.
This morning we made an additional note in our product manual that is related to this, for a different customer. See section 3.6
Let me know if you have additional questions or need further clarification.
TishersParticipantTishers March 29, 2016 at 8:17 am
This had me freaking out a little too. With the USB cable being so short between my computer and the BB60 I had to go with a 5 meter coax to keep my test antenna far enough away as to not overload the analyzer with cellular/bluetooth/WiFi signals.
I was testing in the 928/952 MAS band and just happened to go 0-6 GHz while shutting down and received all sorts of warning messages about overload. The signals were all up in the LTE and WiFi bands. Still, I try to be nice to the front end of the analyzer.
I have the input limiter, 1 dB pad and DC block in-line with the SMA. That just needs to be a normal operating practice as it used to be with the multi-tens of thousands of dollars analyzers of yesteryear.
Time to unbox the low-pass/ high-pass filters to chop out those unwanted interferers.
Justin CrooksModeratorJustin Crooks March 29, 2016 at 9:35 am
If it helps, at the most sensitive setting (-50 dBm reference level), as long as the BB60C is powered on, +20 dBm peak puts the RF power at the preamp right at its absolute maximum, and should not cause damage unless operated in this state for extended periods.
Generally, damage occurs when much larger pulses occur, or when +20 dBm is applied before the device is powered on.
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