I looked. I think we should keep the design goals modest for a first revision. Shoot for a spec that can be hand built on perf board. So I'd relax those numbers by a factor of 1000. The top frequency is in Mhz, not Ghz and the time resolution closer to ns than ps. It's good to have a cheap option. Many people are happy with an FCC1 Try for the next step after that with a goal of actually matching the state of the art in steps.
Why no through holes? I don't see the point of banishing them. I to agree with the rest. SMT that is hand solderable by a skilled tech but now reflow ovens or solder past masks should be required . You might place a limit on component size too like 0.5mm lead pitch or whatever is reasonable. Mechanical part is not easy. Need to re-purpose some mass produced chassis. That keeps leading me back to computer hard drives. What if you made the PCB the same size as a disk drive and then got some 1" x 1/4" aluminum L extrusion and screwed some of the aluminum around three sides of the PCB. low-tech metal work but they might slide into a disk drive enclosure that is made to house SATA drives. These enclosures come in any size for one drive all the way up to 6 foot racks. If yu also place a aluminum L across the short side you have space for conectors and switches On Mon, Dec 20, 2010 at 6:20 PM, Bob Bownes <[email protected]> wrote: > Well said Chris. Take a look at the initial spec in the OpenCounter Gogle > group and tell me what you think with respect to your item #1. I think the > core counter is going to be the really difficult part of the module list. > > Item #2 is going to be a tough one methinks. I love Eurocard, but, as you > say, it is very expensive, if only for the connectors. In cases like this > I'm a fan of either repurposing commercially available connectors (PCI and > memory DIMMS are two I have used in the past) because they can be a) > purchased off the shelf, b) are manufactured in enough volume to make cheap, > and c) are common enough that the really cheap amongst us can get them off > of scrap boards someplace for little or nothing. The N2PK VNA is built to > fit into a particular HAmmond enclosure that I like but again, there are > many options. My feeling is that the enclosure should not dictate any > functional design decisions. > > #3 - I've created a group and appointed myself benevolent dictator. We can > discuss things, propose designs or design criteria, call for a concensus, > accept, and draft volunteers to design that section to the defined spec. If > there are multiple competing designs, so much the better, as long as we all > agree on the interfaces. Sound like a process? Can you tell I've done this > once or twice? :) > > Step one will be to agree on the overall functional spec. If we get enough > participants, I'd like to nail that down by mid January. The next step is to > agree on the interfaces between the modules. Same process, discuss, propose, > draft, get concensus, close and move on. > Then we get folks working on the individual modules. > > > On Mon, Dec 20, 2010 at 8:43 PM, Chris Albertson > <[email protected]>wrote: > >> On Mon, Dec 20, 2010 at 2:51 PM, Dave M <[email protected]> wrote: >> > >> .. never got off the launchpad because of their inability to come to >> > consensus on a set of features. I had to conclude that too many cooks >> > spoiled the broth. Everyone that had input to the project was unwilling >> to >> > yield on anyone else's ideas. Hopefully, our project won't degrade into >> > another such fiasco. >> >> >> THAT is the number one problem to solve. Technical issues are easy >> >> I think the solution is to >> (1) chop the project up into small enough parts, each on it's own PCB >> so that each part is "easy" and has some wider user outside the >> project. >> (2) Find a mechanical standard so all the PCBs can be mounted in some >> kind of chassis. I'm thinking now that maybe a 160-3U Eurocard would >> be about right size. But the parts are expensive. >> (3) Need some sort of design process that allows everyone to >> contribute. And everyone can. Projects always are lacking technical >> writers and quality control people >> >> Of those a "process" and "mechanical standard", I think are the >> hardest. We always give managers a hard time but that is what is >> needed. The person who will make this happen will be a manager and >> organizer maybe not a designer. >> >> >> -- >> ===== >> Chris Albertson >> Redondo Beach, California >> >> _______________________________________________ >> time-nuts mailing list -- [email protected] >> To unsubscribe, go to >> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts >> and follow the instructions there. >> > _______________________________________________ > time-nuts mailing list -- [email protected] > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. > -- ===== Chris Albertson Redondo Beach, California _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
