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.
