--- In Repeater-Builder@yahoogroups.com, "Eric Lemmon" <wb6...@...> wrote: > > You don't move the Invar rods at all- those are the pass adjustments. [...] Just so we're talking apples and apples, the Invar rod is > in the center of the cavity, and it usually has a black knob on it.
OK, so much for re-reading my post so I didn't write something embarrassing! I was calling an apple and orange. The question remains though, how much should I expect to have to move the plastic stick in the reject adjustment? And should I expect to hear a definite center? The duplexer came to me at least 3rd hand. I guess part of what (and why) I'm asking is, does it sound like the notch adjustment is working correctly? [...] > Since you have eliminated the original tuning with experimentation, > perhaps it would be a good idea to properly tune the duplexer with the appropriate test equipment. That would certainly be the best idea, but there are two problems. 1) The only guy I know in the area who had such equipment had his shop broken into recently and among other items taken were his spectrum analyzer and tracking generator. 2) It still doesn't answer the question of how far I should expect to move the adjustment. Using the right equipment would give a nice graphical display of what the adjustment was doing but I still wouldn't know if it was a matter of I was looking for the null in the wrong place or the adjuster wasn't working. > The tuning info is here: > <www.repeater-builder.com/wacom/wp6xx-vhf-tuning-instructions.pdf> Been there, read that. :) (And many other articles about duplexer tuning linked on the site. - thanks for your contributions, by the way) > 73, Eric Lemmon WB6FLY 73, and thanks for the quick reply, even though my nomenclature misnomer was embarrassing. :) rj > > -----Original Message----- > From: Repeater-Builder@yahoogroups.com > [mailto:repeater-buil...@yahoogroups.com] On Behalf Of hbbcara > Sent: Saturday, July 18, 2009 5:48 PM > To: Repeater-Builder@yahoogroups.com > Subject: [Repeater-Builder] wp-639 -- How far should I expect to move the > invar rods? > > > Hi all, > > In tuning the reject for a wp-639, how far should I expect to move the > invar rods to find the notch? > > In tuning mine (the poor man's way - system on the air receiving a weak > station) I didn't find a definite place I"d call a null. There was more > noise on the signal with the rod pushed most of the way in and less > noise with the rod most of the way out, but it was a gradual change. I > expected to find it noisy with the rod mostly in, noisy with the rod > mostly out and at some point in between a quieter spot. > > SO my question is, should I hear a definite "noisy-quiet-noisy" > pattern as I move the rods and if so, over how much motion of the rods > is it likely to fall? An inch? Half-inch? Three inches? Or would that > pattern only be noticeable with "the right equipment." > > (Some background - the duplexer is from an uncertain origin, but it has > a factory sticker saying 146.97 - 146.37 with the ports marked "high > input" and "low input." I'm using it on 146.88/28 so it shouldn't be an > "upside-down" issue.) > > Thanks for any info! > > rj >
