Hello ... Ken Arck wrote: > > At 07:40 PM 4/27/2004 -0000, you wrote: > >Is there any methods of tuning a set of duplexer without having a > >Spectrum analyzer. I am in the learning stages again. I have an > >IFR-500a, so I can generate a signal into them. I know this would > >work somewhat for the receive, but what does one do for the > >transmit.
Long before I had access to a spectrum analyzer etc., I was tuning duplexers ... many of them. I used a signal generator, carefully tuned receivers on the frequencies involved and double shielded coaxial jumpers. > <---Why wouldn't it work for transmit? As a matter of fact, it > would work just fine by both the receive AND transmit sides of the > duplexer. RF is RF, regardless if its -100 Dbm or +10 Dbm, right? A correction here, in polite engineering lingo, a Decibel is one tenth of a Bel, a persons name hence it is dB or here, dBm ... > Depending on what kind of duplexer is it (BP/BR or just BR) > determines the tuning procedure. You might want to check the > website to see if yours is listed. One thing though - It's a good > idea to use a 3 db pad on the receiver you're using for tuning, > since you have no guarantee it will present a 50 ohm load to the > duplexer. The absolute minimum I use is a 6 dB pad ... usually more like a 10 or 20 dB pad. The higher the attenuation, the more closely matched to the 50 ohm reference. > Oh, and don't forget to make sure a 50 ohm load is on the duplexer > port not currently being tuned as well (a 3 db pad would work here > as well). Again, I prefer to use as a minimum here a 6 or 10 dB pad as a termination. A 3 dB pad will have a 6 dB return loss which is insufficient for my tastes. I prefer a higher return loss or, better still, an actual 50 ohm termination. I keep several Bird 50 ohm loads handy for various projects such as the two 20 watt loads up to the 2500 watt water cooled load. I used to have a 10 KW water cooled load with a 3 inch flange connector on it. My shop bench RF coaxial hardware is based on the GR874 series of adapters, attenuators and patch jumpers. If I need to match a 445 MHz 50 ohm source to a unknown termination, I use a pair of GR874 20 cm adjustable stubs connected via GR874 T connectors to tune out the mismatch. > > Ken > ----------------------------------------------------------------- > President and CTO - Arcom Communications > Makers of state-of-the-art repeater controllers and accessories. > http://www.ah6le.net/arcom/index.html > Be sure to see our products at this year's Dayton Hamvention! > Repeater Builders spaces 707 through 710 > AH6LE/R - IRLP Node 3000 > http://www.irlp.net 73, Neil McKie - WA6KLA 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/
