[time-nuts] Low-Cost 6+ GHz Prescaler board for HP/Agilent 53181A/53131A/53132A

[paul swed]

I joined the group this year.
Since I don't have these counters I might be interested in just a free
standing version.
More importantly a couple thoughts.
Use a mar amplifier as the fuse. They are pretty cheap.
Would appreciate seeing the schematic board... So I might understand better.
Regards

On Thu, Mar 25, 2010 at 11:34 AM, Samuel DEMEULEMEESTER <sam at canardpc.com>wrote:

> Last year, I posted a message on timenuts about a project for an internal
> prescaler board for the 53131A (and related 53181A & 53132A) counter.
>
> I successfully cloned the original 3 GHz board from Agilent and I've looked
> further. I then designed a more advanced prescaler PCB based on the Analog
> ADF4107 PLL, able to reach 6 GHz and beyond. I worked on component
> selection
> to get a stable board and I'm now in the final stages of the design
> process.
>
>
> I will order soon a batch of the final PCB and consider selling them to
> recover some of the bucks I spend on the project. My goal is NOT to make
> big
> money, just help some ham and others measurements addicted like me to
> benefit from a frequency extensions for one of the more wide-spread
> counter.
> This said, I need your opinion about some points.
>
> 1- The minimum measurable frequency for that design is 80-85 MHz for a sine
> wave (down to DC with a square wave). To get lower specs, I need to add
> some
> more components to get fast-rising edge in all cases at the input of the
> ADF4107. I don't think there is a need for that as the original 5 GHz board
> for Agilent is rated to 200 MHz min. What's your thought ?
>
> 2- About sensibility, my goal is to achieve -20 dB over the 0.1-6 GHz range
> (as "rated" spec). To get higher sensitivity, I need to add some RF amps.
> It
> would cost more and seems overkill for that application, but .... ?
>
> 3- Let's speak about input protection. More protected = less sensitivity.
> Right now, the front stage is protected by a voltage limiter (2x dual RF
> diode) but it will not support a huge peak (more than 30 dBm). Should I add
> some more protection ? In all case, the "rated" spec will be 10 dBm.
>
> 4- Connectors. The PCB board will input into a standard SMA connector. I
> first planned to provide the board with a short SMA/Type-N cable to mount
> inside the 53131A. This is not possible because the front-panel hole is not
> big enough and will require hardware mod to fit a Type-N connector. So, the
> only other option is a TNC connector at input. Is it a right choice ? A BNC
> @ 6+ GHz seems not a good idea, but works just fine too and is the industry
> standard...
>
> 5- I'm thinking about selling the prescaler board as a "nude" PCB or an
> assembled board. Should I sell a "kit" PCB too ? The board is all SMD and
> the main chip is a fine pitch TSSOP quite hard to solder. This is not for
> beginners.
>
> 6- Price. Last but not least : the price ! Right now, the original 3 GHz
> board costs $1100 and up to $2200 for the 5 GHz. What a ripoff ! You could
> buy some refurbished 3 GHz board on eBay for about $200.
>
> Thanks for your answers !
>
> PS : Two pictures of the Beta 0.7 PCB measuring a 3 GHz / -30 dB signal
> (http://cpc.cx/OB) and a 8 GHz / 0 dB signal (http://cpc.cx/OA)
>
> PS2 : Sorry for my bad English.
>
> ---------------------
> Samuel DEMEULEMEESTER
> Presse Non Stop - Canard PC
> http://www.canardpc.com
> Tel : +33.6.13.73.4003
> MSN : sam at x86.fr
>
>
>
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