Re: [Repeater-Builder] Re: wp-639 -- How far should I expect to move the invar rods?
Hopefully, you have only tried to tune on of the cans. If you still have a can that is tuned to the original frequency they were working (???) on, try to follow the procedure on repeater builders carefully. If you get that one working, you can try to set the rods to the same dimensions as the good one a try to tune the other ones. It is possible to get a duplexer working satisfactorily (but probably not optimally) without the proper test equipment (tracking generator, etc) but takes a lot of patience and time. I did it many years ago to a set of homebrew 220Mhz cans with an HT and an RF detector on an Oscilloscope. After several nights of tuning and graphing results I got them to work very well. If you start with a working set of cans, moving them to a new frequency is easier. It sounds like you need to hook up with someone that has a service monitor or a network analyzer. Where are you located? Maybe someone can give you a hand. 73, Joe, K1ike
Re: [Repeater-Builder] Re: wp-639 -- How far should I expect to move the invar rods?
There's no way to tell how much, the adjustments interact with each other. Chuck WB2EDV - Original Message - The question remains though, how much should I expect to have to move the plastic stick in the reject adjustment?
Re: [Repeater-Builder] Re: wp-639 -- How far should I expect to move the invar rods?
Joe is correct, if you're going to try an tune it without the proper test equipment, you will not get it perfect. It may work, but not as well as it could. Early in my career, I was able to tune a duplexer with a couple HT's, one for xmit and one for receive, but I found I needed a step attenuator to keep from saturating the receiving HT. I was really proud of myself cause I could tune for the peak and the null by using this method. It worked, but later when I had access to the proper equipment, I checked the duplexer and found I missed the proper settings by 10 Db on one side and 15 on the other. I don't think there is anyway you'll be able to tune it by ear. Try and find someone with the proper gear, you'll be much happier in the end. Gary - K7NEY Joe wrote: Hopefully, you have only tried to tune on of the cans. If you still have a can that is tuned to the original frequency they were working (???) on, try to follow the procedure on repeater builders carefully. If you get that one working, you can try to set the rods to the same dimensions as the good one a try to tune the other ones. It is possible to get a duplexer working satisfactorily (but probably not optimally) without the proper test equipment (tracking generator, etc) but takes a lot of patience and time. I did it many years ago to a set of homebrew 220Mhz cans with an HT and an RF detector on an Oscilloscope. After several nights of tuning and graphing results I got them to work very well. If you start with a working set of cans, moving them to a new frequency is easier. It sounds like you need to hook up with someone that has a service monitor or a network analyzer. Where are you located? Maybe someone can give you a hand. 73, Joe, K1ike
Re: [Repeater-Builder] Re: wp-639 -- How far should I expect to move the invar rods?
If you bring them to me I will (try to) tune them for you... No charge. - Original Message - From: Repeater-Builder@yahoogroups.com Repeater-Builder@yahoogroups.com To: Repeater-Builder@yahoogroups.com Repeater-Builder@yahoogroups.com Sent: Sun Jul 19 07:33:17 2009 Subject: Re: [Repeater-Builder] Re: wp-639 -- How far should I expect to move the invar rods? Hopefully, you have only tried to tune on of the cans. If you still have a can that is tuned to the original frequency they were working (???) on, try to follow the procedure on repeater builders carefully. If you get that one working, you can try to set the rods to the same dimensions as the good one a try to tune the other ones. It is possible to get a duplexer working satisfactorily (but probably not optimally) without the proper test equipment (tracking generator, etc) but takes a lot of patience and time. I did it many years ago to a set of homebrew 220Mhz cans with an HT and an RF detector on an Oscilloscope. After several nights of tuning and graphing results I got them to work very well. If you start with a working set of cans, moving them to a new frequency is easier. It sounds like you need to hook up with someone that has a service monitor or a network analyzer. Where are you located? Maybe someone can give you a hand. 73, Joe, K1ike
