Joe, Thanks for the reply. They are pass/notch. (Moto 1500 series) Right now the repeater is in a sight that should really work well (300ft tower) but is in a hole topo wise, in right next to a hill. So really trying to get sensitivity out of the thing. No desense, the best I can tell.
Just in a noisy repeater shack that is pretty hard to hear the "quieting" of the rx (have to use head phones...and is still pretty hard to hear). Had a friend put it on his bench and really worked it well with his service monitor. I was just hoping to (and did somewhat by ear) match it a little better to the repeater antenna and feedline. Have limited equipment myself (Cushman CE-5 and Moto s1327B ?, CE-15...plus Moto test set) and was hoping for a "visual" to combat the external noise factor. BTW, I changed out the preamp from the P432VDA to a P432VDG. BTW2, I need a UHF preselector for the Moto if someone has one for sale. Thanks, Robert --- In [email protected], "Joe Burkleo" <[EMAIL PROTECTED]> wrote: > > --- In [email protected], "georgiaskywarn" <kd4ydc@> > wrote: > > > > Ok on both from both Kevin's. > > > > Do have a preamp in line. Will try it out. > > > > Now...can the test set not be used as a "scale" with a weak signal to > > "touch up" the rx side of the dup.s? Not wanting to mess with the > > front end of the receiver. Are you also saying I should see something > > on meter setting 4+? > > > > Is "tweaking" the cans not possible with the test set? > > Robert > > KD4YDC > > > Robert, > > Position 4 if I remember correctly is the discriminator position, and > should not be used for signal strength indication. > > What you are asking about "tweaking the cans" depends on what type of > duplexer you have. If it is a pass or pass/notch duplexer, you may be > able to rock the pass tuning rods 5 to 10 degrees max to hear or see a > difference. Preferably with a very weak signal. If you need to move > the adjustment more than that, you have some more serious problems. Do > not do this if you have a notch only duplexer. > > Also you can try and rock the transmit pass adjustments with a > wattmeter in line, the same 5 to 10 degrees and see if the transmit > power increases any. Often times if it is desense you are fighting by > fine tuning the transmitter pass side you are also helping the > receiver notch. Most duplexer tuning instructions caution you to not > touch the notch of either side while transmitting, this is most often > a recipe for disaster. > > If you decide to twist on the duplexer make sure you have the preamp > and all the proper cables in place or the tuning could change once you > put the preamp back in. Sounds like you have a catch 22 situation, you > need the preamp out to get a good valid meter position 5 indication > and you need the preamp in to make sure it does not change the > duplexer tuning when in-line. Depending on which brand of preamp you > are using, you may or may not see a change. Some of them look pretty > ugly on a return loss bridge, and may not present a true 50 ohm > impedance to the duplexer or receiver. > > A better way to do this is with a signal generator connected to a > isolated tap or a isolated tee fitting on a wattmeter that is > connected to the output of the duplexer and the antenna. > > Good Luck, > Joe - WA7JAW >
