----- Original Message ----- From: "Bruce Griffiths" <[EMAIL PROTECTED]> To: "Discussion of precise time and frequency measurement" <[email protected]> Sent: Friday, June 13, 2008 8:37 PM Subject: Re: [time-nuts] Non-impedance matched antenna cables
> Magnus Danielson wrote: >> Hi fellow time-nuts, >> >> For those of you that isn't aware of it, using 75 Ohm antenna >> cables rather >> than 50 Ohm cables is a bad move, as the antenna cable itself will >> create a >> multi-path system. This article elaborate on reflections i cables: >> >> http://tycho.usno.navy.mil/ptti/1998/Vol 30_39.pdf >> >> Nothing new, but needs to be said, especially with Thunderbolts >> getting more >> popular, as the manual clearly recommends 75 Ohm cable as I recall >> it. Do not >> listen to that. >> >> Cheers, >> Magnus >> >> > Hej Magnus > > If one uses cheap cable with relatively high attenuation at L1 this > may > not be a problem. > However the active antenna may need higher gain to compensate. > The question is just how much one way cable attenuation is required? > > A considerable reduction in this effect can be obtained by making > the > cable length close to an odd multiple > of one-half the signal wavelength (½λ) in the cable. > > Bruce Has anyone actually measured the TBolt rx input impedance at L1? DaveB, NZ _______________________________________________ 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.
