[time-nuts] DIY Frequency extension for HP Agilent 53181A, 53131A or 53181A

Max Skop mskop at bigpond.net.au
Sun Feb 15 01:07:42 UTC 2009

Hi Samuel and all,
Welcome to the group.
I also have a 53131A and would welcome any way to enhance or upgrade the 
performance of this instrument. Please count me in on clone option parts.
As can be seen from the picure of the 3Ghz option there is nothing special 
in its construction.  Just four stages of amplification and a divider. Only 
need to ID the parts to copy and determine the pinout of the connector.  The 
mounting holes would also have to be accurately positioned.

----- Original Message ----- 
From: "Samuel D. [x86/CPC]" <sam at canardpc.com>
To: <time-nuts at febo.com>
Sent: Sunday, 15 February, 2009 6:30 AM
Subject: [time-nuts] DIY Frequency extension for HP Agilent 53181A,53131A or 

> Hi there,
> First, let me introduce myself : I’m a 28-years-old electronic engineer 
> working for a press magazine as Hardware & Test Chief Editor. I’m from 
> France; so, please forget about my bad English. Since years, I’m obsessed 
> with precision measurements and I spend the last 15 months finding the 
> best way to accurately measure a couple of femtoamperes or nanovolts. For 
> 2009, my new goal is to be able to measure the mHz part of a GHz signal 
> so, I need ultra high accuracy frequency standard and other fancy things 
> like that.
> But here is the problem: I’m not rich and I don’t have enough money to 
> build Agilent’s and Symmetricon’s stuff at MSRP. In the other hand, I love 
> precision equipment and high quality, well-known hardware. After all, its 
> 90% hobby and 10% professional, so, why spend thousands of dollars on a 
> brand new Rubidium standard when you can build one with a Datum module 
> found on eBay for a small fraction of that price? That’s what I will do in 
> the upcoming weeks.
> By the way, as you know, the two first equipments to own for precision 
> time measurements are a high stability frequency reference and a good 
> counter. Building the first one is quite easy but a good counter is 
> something expensive. Fortunately, I just bought an Agilent 53131A for €350 
> on eBay and I’m really happy with it. As usual, I will now spend some time 
> to see how I can improve it.
> HP/Agilent 53181A, 53131A & 53132A are probably the most used frequency 
> counters in the world. They come with two kinds of options: three advanced 
> time-bases (an OCXO with 2x10e-7, 1.5x10e-8 or 3x10e-9 monthly aging rate) 
> and four frequency extensions. These counter’s max base frequency is 225 
> MHz and may go up to 1.5, 3.0, 5.0 or 12.4 GHz with an additional PCB 
> linked to a BNC or type-N connector acting as Channel 2 (for 53131A) or 
> Channel 3 (for 53131A and 53132A).
> As often with Agilent, the price for those extensions is clearly and 
> indecently overpriced: more than $2000 for the 3 GHz option, the price of 
> the counter itself. Overpriced, Really? Yes! And if you still doubt, here 
> is an anecdote from my experience: the Agilent 34420A Nanovolt Meter comes 
> with a low-thermal input connector. Last year, I wanted to build a custom 
> cable and I asked Agilent the price for a male connector. They quoted that 
> small part more than €100. After lots or research I found the exact same 
> connector, originally built by Lemo, and bought it new for less than $15.
> Ok, come back to the 53131A frequency options. The extension sold by 
> Agilent is nothing more than a prescaler (probably /16, /32, /64) mounted 
> on a small PCB and connected to the counter with a standard ribbon cable. 
> The PCB is really small and there is no more than 20 components built-in 
> as you can see here : http://www.x86.fr/temp/003.jpg (3 GHz option) and 
> http://www.x86.fr/temp/124.jpg (12.4 GHz option). From a good source, the 
> prescaler is not built by Agilent and all components are available from 
> third-party.
> My target is to create a clone of that extension. I think it will not cost 
> more than $50. Then, I’m planning to offer a “DIY frequency extension kit” 
> for sales for all time enthusiasts and without making profit.  Every owner 
> of a 53181A, 53131A will be able to add the nice freq extender for a 
> fraction of the MSRP. But I need some help. The first thing to do is to 
> find someone with an original -003, -005 or -124 extension and willing to 
> scan (or take pictures of) the card in high resolution in order to 
> reproduce the schematic and layout used by Agilent. Knowing the pinout of 
> the J2 connector will be useful too. Then, I will create a PCB and find 
> the good replacement components...etc.
> Do you think this project is a good idea and may interest somebody other 
> than me?
> Please share your thoughts ;)
> Regards,
> ---------------------
> Presse Non Stop - Canard PC
> www.canardpc.com
> MSN : sam at x86.fr
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