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Old 31-Jan-2015, 5:30 PM   #1
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Juice Pre-amp

Is anyone using or has anyone seen the Juice pre-amp? I am wondering how well shielded it is. Most of the (affordable) pre-amps I have looked at have plastic cases and would offer little shielding from my nearby ham radio antennas.

Last edited by Tim; 1-Feb-2015 at 7:01 PM. Reason: Added link to website and corrected mis-spelling
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Old 31-Jan-2015, 6:09 PM   #2
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Can you post a link? Tried googling & don't see it.
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Old 31-Jan-2015, 7:34 PM   #3
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It's about the most shielded pre-amp you'll ever see in this market space. Molded metal housing with a steel back plate that is soldered, not glued, to the housing.

If you experience ingress when using this amp, it probably isn't coming in through the housing.

The Juice is pretty much a re-done CPA19. We had to change manufacturers so we redid the name, the physical packaging (we kept the metal injection mold), the power supply and, internally, the filtering. The CPA19 had a filter that suppressed between 250 and 400+ MHZ, the Juice deleted that filter and replaced it with one that rolls in just above 700 MHz for 4G/cellular suppression. There was only enough circuit board real estate available for that one filter, so it's the only one in the Juice. FM filtering, if needed, can be done with one of our external full band filters.

Gain averages about +18 dB +/- ~1 dB across design band of 54-698 MHz.

Noise figure averages around 2.5 dB in low-VHF, ~1.75 in high VHF, and averages sub 3 dB on UHF. The gradual roll-in of the 4G filter slightly affects the top end of the UHF band. TANSTAAFL, as they say.

As far as IMD performance, it tests out to between +35 and +38 dBm TOI (Third Order Intercept), depending on the frequency at which it is tested. My personal observation is that this model is the most overload resistant amp that's come across my workbench so far.

For those who hate TOI results, I've tested a few other protocols. Frankly, testing this thing for overload is a PITA because my test gear doesn't readily produce hot enough signals and the dynamic range of the Rigol isn't all that wide. It is necessary to use attenuation on its input to keep the mixer input below -10 dBm so it doesn't introduce any IMD of its own which affects the ability to display weak and strong signals at the same. Depending on the RBW and attenuation settings, it's hard to achieve 70 dB of dynamic range. But, hey, it's a $2K piece of gear, not several 10s of thousands of dollars.

A sampling of test results:
505 MHz with IP3 @ -46 dBc --- +61.9 dBmV (+13.1 dBm) fundamental output
505 MHz with IP3 @ -60 dBc --- + 7.7 dBm (TOI=37-38 dBm) fundamental output
DIN45004B 3-tone @~500 MHz --- 119.35 dBuV

Several notes: Samples from the same batch of amps will vary, sometimes by several dB. Also note that the Rigol's accuracy is somewhat limited in its precision (+/- 1 or 1.5dB IIRC). Far more accurate lab gear would reduce the results range for greater accuracy but that is outside my assigned charter. In general, the readings taken with the Rigol are very close to those obtained by our test lab engineer in his facility with his HP/Agilent gear.

P1dB test results usually ranged between +21 to just over +23 dBm depending on the individual sample and the test frequency.

I will be happy to try to answer any performance related questions that you might have.
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Last edited by ADTech; 31-Jan-2015 at 7:38 PM.
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Old 31-Jan-2015, 9:22 PM   #4
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Thanks for the run down on the Juice. Very glad to hear that it is well shielded. I may have to move my antenna to a new location with a longer cable run. I am currently using a distribution amp but with a longer cable run from the antenna I may have to try a preamp and a splitter. At least I will have an option now that I know there is an affordable shielded preamp on the market.
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