Sunday, August 5, 2018

Agilent 53132A 53131A 53181A DIY Open Source 3Ghz Channel Option 030 Board

As mentioned my Open source Agilent OCXO upgrade post, I mentioned, I have bought a Agilent 53132A a 12 digit universal counter, more capable than commonly known 53131A 10 Digit Counter. Both are really nice units though.

unit i have bought did you have ultra stable oven oscillator so i made oven board, this unit also have option for third channel, my unit did not came with any third channel.. which is capable for frequency up to 12.5 Ghz with correct option installed. These optional board contains RF Gain blocks and frequency prescaler chips. many people have made there own DIY units but none of the is open source. So i have to make one open source DIY Design.

Although i did not needed any RF counter, but i still decided to make my self 3Ghz prescaler. Because when i was doing oven board so it was no too much hassle to make one more board.

here is how board looks

Here is the Schematic
All the source , PDF File are available in my github repo , here.

Here is how PCB Looks
All the source , Gerber File are available in my github repo , here.

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Blank PCB only , HASL Finish

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As this is basically my first time playing with 50 Ohm RF Gain Blocks so i wanted to make sure everthing  is right , i do have 3Ghz Spectrum analyzer in my oscilloscope, so i can verify if all the RF Gain block correctly functional.

I made few Test , with 50Ohm dummy load, and also bough cheap diy kind of 1.5Ghz active probe to  test. there were few limitation in each time of test which i will Describe shortly and also in a youtube video i put explaining this project.

Test 1:
I first tested each ~7db gain block separately, because these are 50 Ohm  Gain block you need to have 50Ohm load on the output so i connected 50 Ohm Terminator and then either verified gain with the high impedance oscilloscope probe or with an active probe.
if  your spectrum analyzer  is 50 Ohm terminated then you can connect spectrum analyzer directly to the ouput of the gain block without any 50 Ohm terminator.

Test 2:
when every thing is assembled, and you have verify gain at each stage, i can no longer connect my spectrum analyzer to it, even connecting high impedance oscilloscope probe with change the behavior of the circuit totally  so i have to use active probe connected to spectrum analyzer only.

Test Video

More image 

On the back of the board there is 6 Ghz MCX connector and original Amphenol MCX to BNC cable will be connector between front panel and the board.

as i was not sure about generally available mcx bnc cable, i went extra lenght to get Amphenol MCX to BNC cable for better quality

Top Quality Amphenol MCX to BNC cable 


  1. Gaurav, thanks a lot for the project! I'll sure build one for my 53131A...But I'm curious, why 4-stage amplification? Couldn't you just use ONE MAR or ERA MMIC from Mini-Circuits? Thanks and greetings from Brazil! =)

    1. Primary reason to use 4 MMIC is to achieve needed gain levels and needed sensitivity. There are new MMIC available which can achieve this by just one or two stages. But to keep the original design, I have left it as is.

  2. Hi Gaurav. I found small inaccuracy in BOM xls sheet. R1 and R3 is NC (unused?) Tony

    1. That is very well a mistake in BOM , Will be corrected.

  3. Is there any other chips which can be used to replace MB510? This one is too hard to buy.