If the tunable stub is connectorized, then just add a 90 degree connector in line to make it a bit longer.
It depends on the version of the old stub Q202 duplexer you have. Is it side mounted or top mounted loops and are there 4 or 8 pieces of coax being used? Is the harness connectorized with separate Ts or is it one assembly? The coax lengths should be a little longer but I think 2" is too much if I remember correctly. You should still be able to make it work with that cable harness. A good working stub Q202 is better than a new Q202 with capacitor loops. Harold, VA3HF --- In [email protected], Burt Lang <[EMAIL PROTECTED]> wrote: > > What you are experiencing is the symptioms of insufficient capacity to > pull the notch down low enough on the low pass side. The capacity range > of those "tuning stubs" is determined by the length of the center rod > inside the plastic stub. They are 3/16 (I think) diameter brass rod with > a threaded end. Sinclair had several lengths available, the longest one > being about 6in long. There is probably nobody left at Sinclair that > even remembers that part as that design dates back to the 1950s or 60s > and was superseded by the Johanson trimmer design in the late 1960s. You > should be able to get a local machinist to make you a longer one using > the one you have as an example. > > Burt VE2BMQ>>> > > > > Jim Brown wrote: > > > I am trying to move a Q 202 G from the 170 mHz range down to the 147 mHz > > range and have run into a problem on the notch tuning. The high pass > > tuning works like a charm and has a good pass and notch characteristic. > > The low pass side is another story. The pass tuning works fine, but I > > can't get a notch. With the tuning rods all the way in, it is starting > > to notch, but only about 20 db. > > > > Here is the strange thing - I took the coupling loop out of the high > > pass side and compared it to the low pass side, and they are identical. > > The tuning rod varies the capacitance across the single loop connector > > and there is no inductance in the circuit for either high pass or low > > pass side. How does the same hookup work to allow a notch on the low > > side as well as the high side? > > > > I am tempted to add a small fixed capacitance across the loop to see if > > that helps the tuning for the low pass side.. > > > > Any comments on which way to go? > > > > 73 - Jim W5ZIT > > > > > > > > > > > > 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/
