I think the same could be said for using 75 ohm cable. One could run quad shield rg-6 with BNC connectors in the lab. It will have lass leakage then even the best rg58. then you can terminate as required. The quad shield is foil-braid-fiol-braid and is even better then the 100% coverage conventional cable.
One annoying thing about the rg6 is that it is stiff. Not good for test leads but for clock distribution being stiff is ok. If you want the best, use hardline. I picked up a little bit of this by accident when I bought a lot odds and ends. It looks like coper pipe with RF connectors on each end. I have no idea how you put the connects one put you can bend it with a tubing bender and it is not hard to work with. But seriously if you want low leakage the cable TV stuff is designed just for that. On Sun, Apr 21, 2013 at 12:22 AM, Luciano Paramithiotti <timeok...@gmail.com > wrote: > Hi all , > normally the external frequency standard input are not 50 OHms , but all > the distribution amplifier have 50 Ohms of standard output impedance. This > because the standard cables used to connect the devices are 50 ohms. > Case one: External Zi input 50 ohm: direct connection with rg58 cable. > Case two: External Zi input 1k or more (as example) use the RG58 cable with > a 50 ohm as termination in parallel to the instrument input. > > This second setup is to avoid any standing waves on the cable that produce > unwanted phase and amplitude modulation; this is a cost-less best > practics to apply . > > Luciano > www.timeok.it > > On Fri, Apr 19, 2013 at 2:54 AM, <dlewis6...@austin.rr.com> wrote: > > > External reference inputs are definitely not all '50-ohms.' > > > > 'Learned the hard way. > > > > You need to read the specs on each piece of equipment. > > > > Input impedances will vary all over the map, even within the HP line. > > > > -Don > > > > > > > > > > > > > > > > > > > > ---- Hal Murray <hmur...@megapathdsl.net> wrote: > > > > > > c...@omen.com said: > > > > I have a FlexRadio 1500, Racal 1992 counter, HP 3586, Advantest > U3641, > > and > > > > Gigatronics 6061A daisy-chained off my Thunderbolt. Don't throw out > > those > > > > BNC T connectors. > > > > > > I thought most boxes would have an internal 50 ohm terminator so at > > first, > > > I'm a bit surprised that it works. > > > > > > If cables are short (which is not hard at 10 MHz), it would just be a > > > resistive divider. If the source impedance is low, it's just more work > > for > > > the driver. If the source includes 50 ohms, that's a 5:1 (1/6) divider > > so it > > > probably works if the receivers are reasonably sensitive. > > > > > > > > > > > > -- > > > These are my opinions. I hate spam. > > > > > > > > > > > > _______________________________________________ > > > time-nuts mailing list -- time-nuts@febo.com > > > To unsubscribe, go to > > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > > > and follow the instructions there. > > > > _______________________________________________ > > time-nuts mailing list -- time-nuts@febo.com > > To unsubscribe, go to > > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > > and follow the instructions there. > > > > > > -- > Luciano > Timeok > visit : www.timeok.it > _______________________________________________ > time-nuts mailing list -- time-nuts@febo.com > 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 -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
