None left from that batch. Hope you got yours. Points taken, but cheap enough to experiment with.
Le 8 août 2013 à 13:08, Dr. David Kirkby a écrit : > On 6 August 2013 09:37, Raj <[email protected]> wrote: >> Found this on Hack-a-day >> >> http://www.youtube.com/watch?v=chrzrod3tQY >> >> Cheers >> >> -- >> Raj, VU2ZAP > > Interesting video. I decided to but one of the distribution amps. I > already have the rubidium. There were a few things that struck me in > the video. > > 1) Having a PIC to control an LED seems a bit OTT. Personally I'd just > stick a second LED - one as a power indicator, the other as a lock > indicator, rather than make it flash when warming up, and solid when > locked. > > 2) If one does have a flashing LED, it would be better if it is > slower, in case there are any epilepitcs about. As someone who suffers > from photosensitive epilepsy, I would not want it flashing any faster > than 1 Hz. He should just about be ok, but I'd feel a bit happier if > it was slower. > > 3) I'm not really convinced there is a need to change the output > impedance from 75 to 50 Ohms. The impedance mis-match is pretty small. > > 4) More concerning to me would be the fact the output connectors are > 75 Ohm, and so would be damaged with the larger male pin of a 50 Ohm > connector. I guess one might get away with it given one is not going > to be disconnecting this a lot, but I think I'd buy 75 Ohm BNC plugs > to put on one end of the cable, and 50 Ohm BNC plugs on the other end, > sticking a bit of heatshrink on the 75 Ohm end of the cable so I know > they are not standard BNC cables. > > 5) I wondered if there is enough cooling air there? What size heatsink > would be optimal? I think unlike most electronics, one does not want > to cool the rubidiums too much, so "bigger is better" might not apply > here. > > 6) Is the use of a SMPS a good idea? I thought the Rb oscillators > should be powered from a linear supply. I don;t suppose it is possible > to get a linear power supply in there. > > 7) He scrapped the BNCs configured as digital lines. I would have > thought it worthwhile bringing out a 1 pps output, which I think those > Rb oscillators have. > > 8) I wonder if one could fit a GPS locking module in that box and > antenna connector on the box. > > 9) It will look very odd to have the heatsink as the front panel !! > But I guess that is a small price to pay for getting a reasonably > sized box and > > 10) I suspect the box will be hard to keep in place, since with a > dozen or so BNCs on the rear, that is going to go where the cables > tell it to go, rather than the other way around. Perhaps a heavy > heatsink will mittigate that. > > 11) If I recall correctly, there is a way of adjusting the freqency of > those rubidiums, though I guess for the intended application, a Rb is > plenty good enough. I know it is for me, but perhaps not for a > dedicated time-nut. > > Dave, G8WRB > _______________________________________________ > 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.
