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

Samuel DEMEULEMEESTER sam at canardpc.com
Thu Mar 25 15:39:41 UTC 2010


Damn, I forgot to finish the "Price" point.

So, what seems to be a "fair" price ? My goal is €49 for a PCB, €99 for a kit and €149 for an assembled/tested board. It's just a first estimation of what seems fair for me. I still need to check the real price of components and the price will change with the number of buyers, of course. 

---------------------
Samuel DEMEULEMEESTER
Presse Non Stop - Canard PC
http://www.canardpc.com
Tel : +33.6.13.73.4003
MSN : sam at x86.fr 


-----Message d'origine-----
De : time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] De la part de Samuel DEMEULEMEESTER
Envoyé : jeudi 25 mars 2010 16:35
À : 'Discussion of precise time and frequency measurement'
Objet : [time-nuts] Low-Cost 6+ GHz Prescaler board for HP/Agilent 53181A/53131A/53132A

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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