I'm assuming that if the old RG-8 cables are being replaced with RG-214 cables that are the same length, that the velocity factors of both types of cable are the same.....
-----Original Message----- >From: "Bob M." <[EMAIL PROTECTED]> >Sent: Dec 19, 2005 7:10 PM >To: Repeater-Builder@yahoogroups.com >Subject: Re: [Repeater-Builder] Re: Old duplexer tuning question > >New cables will be a lot more flexible, and with >RG214's double shield, they should work better too. >It's tempting to use the coax and TEE fitting as a >handle when picking the unit up - don't do that ! > >I found that the connectors added exactly 1/2 inch to >the cable length PER CONNECTOR, so you would want to >cut the coax 1 inch shorter than the final lengths of >11-1/2 and 12 inches. I solder the center pin, rather >than crimping it. > >Not too many analyzers will be able to go down to the >100+ dB that these duplexers are capable of providing. >That's one reason why they tell you to tune each >section separately. I did find that if I use my signal >generator at a fixed frequency, rather than the >sweeping tracking generator, I can tune the spectrum >analyzer to the same frequency and crank down the >filters. I can barely see the sig gen around 120dB >down or more, on the final configuration. > >As others have mentioned, if your equipment does not >provide a good 50 ohm impedance, you should use 6-12dB >pads on each line connected to the section you're >tuning. Of course, adding this attenuation pushes the >signal even further down into the noise, but it should >not be a problem on any single section. Use as much >signal from the tracking generator as possible (i.e. >+10dBm or more). > >The resulting notch from the entire duplexer will >appear to be quite wide, even though the individual >section notches are quite narrow. > >Good luck with it in the morning when it's warmer. > >Bob M. >====== >--- tony dinkel <[EMAIL PROTECTED]> wrote: > >> All, thanks very much for the input. I was already >> in the process of >> rebuilding the interconnects to RG-214 with crimp on >> RFS connectors as >> a punt. That old RG-8 was hard as a rock. >> >> I also think my problem with the notches is that I >> do not have enough >> dynamic range on my ifr 1600 to see the bottom. It >> works ok on the >> individual cavities but once I combine the whole >> circuit thats when it >> mushes out. >> >> I think I will get this thing knocked out in the >> morning. This place >> is getting dark and cold. >> >> Thanks, >> >> td >> wb6mie > >__________________________________________________ >Do You Yahoo!? >Tired of spam? Yahoo! Mail has the best spam protection around >http://mail.yahoo.com > > > > > >Yahoo! Groups Links > > > > > > Yahoo! Groups Links <*> To visit your group on the web, go to: http://groups.yahoo.com/group/Repeater-Builder/ <*> To unsubscribe from this group, send an email to: [EMAIL PROTECTED] <*> Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
