Products > Test Equipment

Replacement for the PM9610 Prescaler for Philips PM6654 High precision Counter

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Fraser:
Hiya,

As previously stated, I would love to buy a board from you. You could place then in the Buy and Sell section of this forum for our fellow members. Set your price to that with which YOU are comfortable. I.e. I do not expect you to sell them at cost. Once you have fed the forum members with their needs you will get feedback on performance and any issues. You then have the option to sell PCB's and/or complete kits on eBay with Bona Fide quotes from happy members here who have built it. Such feedback is invaluable for sales. You can also reference this forum thread as part of the eBay auction.

I would buy a complete kit of parts if it were available so please consider me a very interested party.

Best Wishes

Fraser

ON5Bi:
Hi

If a prescaler PCB, or PCB comes available to purchase, I would love one to.

Marc

SaabFAN:
Short update:
- Boards are still listed as "Producing" on the ShenZhen2U Website
- If someone is interested, here is the Link to the CircuitMaker project: http://circuitmaker.com/Projects/Details/Thorsten-Schroeder/Philips-PM9610-Replacement Maybe if there are enough "thumbs up" for it it gets to the main page with the features projects  ;D

SaabFAN:
The boards are here and my curse strikes again: They kinda work, but not too well -.-

As you can see on the attached pictures, there's alot of noise and oscillation in the signal after the first prescaler and it gets worse after the second prescaler.
As you can imagine, the counter doesn't really know what to do with such an unclean signal and displays higher frequencies than the one that is put in. With no input the counter counts about 1,21GHz, which is probably the noise that gets amplified and lowpass-filtered by the DC Block-Capacitors.

At the moment I have the following culprits:
- The Prescalers are capable of too high frequencies and are toggling on a harmonic as well as the fundamental frequency - They are capable of 2.5GHz and per datasheet their useful operation area starts at 500MHz. This would mean I need other prescalers.
- Noise gets amplified enough for the prescalers to toggle on them, which I would say is unlikely because I have to go down to 10mV/div on my scope to see noise on the supply-lines, which is probably already inside the noise-floor of the scope. This would mean bigger or more caps.
- The prescaler cannot be connected directly to each other and require DC-Blocks to work properly. This would mean I have to hack the board to get a DC-Block in there.
- The prescalers need larger output capacitances to suppress parasitic oscillations and harmonics. This could be fixed the easiest way: Just add a bunch of caps :)

Any other reasons for this behavior?

artag:
I had this problem some years ago when I made a prescaler for another Philips counter. I didn't have the original schematic so I just adapted a prescaler from another design (an Elektor project that used an MB512).

In my case, it was OK when given a reasonable signal, but tended to read non-zero when disconnected. The problem is self-oscillation. If you google prescaler self-oscillation you'll find it's a common problem with most home made designs. I think one way of dealing with it on commercial designs is to block the divided signal if it's below the level the input can work reliably with.

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