Products > Test Equipment
Beehive vs. Tekbox EMC probes and amplifier
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pdenisowski:
Here are the gain and noise figure of the Tekbox preamp (TBWA2 - 20 dB version, measured with a R&S FSW spectrum analyzer and the FS-SNS (smart noise source)


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matthuszagh:
Well it sounds like their "specifications" are more like typical performance and that typical performance really isn't so typical, considering this is a good deal worse than the spec sheet. Good to know...
_Wim_:

--- Quote from: nctnico on May 09, 2023, 06:07:34 pm ---@pdenisowski: It would be nice if you could also measure the 'Amazon' pre-amplifier to see how it stacks up.  ;D

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Hi, a while ago I measured another Chinese preamp (see pictures attached) with an HP8970A & 346B noise source, and it did meet it spec quite reasonable.


Spec according to Ali-Express:

Gain: typical value 31dB-0.5G input output impedance: 50Ω
Maximum output power: P1db 11dBm-0.5G
Input signal: <0dBm (>0dBm input signal has been distortion)
Bandwidth: 50K-2GHZ (different gain in different frequency)
Noise coefficient: 2dB-0.5G

As I did not want to bother writing an application for the HP 8970A, I just used in XY plotting outputs. My picoscope does not have a blanking option, so the retrace is also visible.

Plot is from 0 to 1.6GHz (so 160MHz per division)

Bottom trace is the noise figure (1dB per division): noise figure stays below 2dB up to 1GHz, and never goes above 3dB.
Top trace is the gain (4dB per division): gain up to 800Mhz is fairly flat and around 32dB and drops to 25dB at 1600MHz.

For only 14€ including shipping, this is quite a useful amplifier.

I also have one based on a SPF5189 that looks like the one in the attached picture, when I have some time in the lab I will try to measure this one also.

_Wim_:

--- Quote from: _Wim_ on May 14, 2023, 09:08:24 am ---I also have one based on a SPF5189 that looks like the one in the attached picture, when I have some time in the lab I will try to measure this one also.

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Also this amplifier seems to reasonable meet is specs (and the specs of the SPF5189). I am picking up some noise in the lab, the spikes on the noise factor come and go. For about 4€ including shipping a very useable device also.

pdenisowski:

--- Quote from: _Wim_ on May 18, 2023, 01:00:33 pm ---I am picking up some noise in the lab, the spikes on the noise factor come and go.
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Not much you can do about direct pickup, but noise figure is one of the few measurements where I use a proper torque wrench to tighten connectors :)   

It's very easy to get screwy NF results from environmental noise, especially if your lab is anything like my lab.

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