The inner conductor of the capacitors needs to be lengthened and the cables changed to the appropriate length will help signifigantly.
On 6/3/05, Kevin Custer <[EMAIL PROTECTED]> wrote: > Hi Rob, > > Rob Martin wrote: > > > > Kevin > > > > Thanks for tips, I had download the VHF tune up PDF but not the other pdf. > > I was surprised he had such problems as I had bought two sets of duplexers, > one was a DB products until which he said failed as they had 2 notches and > the second set being the wacom which he said wouldn't tune down. > > > > When you say tune them upside down could you explain a little further for me > as this is my first attempt to put a repeater on air. > The Wacom WP-639 is a BpBr design, meaning Band Pass - Band Reject. The > duplexer is specifically built to pass a particular frequency, and reject > another. The components of the duplexer determine if the notch falls above > or below the pass frequency. In the case of a regular duplexer, one side is > HPLR (high pass low reject) and the other is LPHR (low pass high reject). > Many times, from the factory, a duplexer has its ports marked "Transmitter" > and "Receiver", but those terms are meaningless unless the duplexer is used > in the same band segment as it was tuned from the factory. Let's look at it > this way, say you have a repeater on 146.625 minus 600 kHz. This repeater > would be HPLR on the transmitter and LPHR on the receiver. Follow me? > Now, lets look at 147.195 plus 600 kHz. This repeater would be LPHR on the > transmitter and HPLR on the receiver, or exactly opposite. This means if > you bought a duplexer that was originally built for 146.625 - and retuned it > to 147.195 +, you'd have to ignore the references to port identification > "TX" and "RX" and connect them inversely. If you tried to tune the HPLR to > LPHR, the duplexer wouldn't tune; it would likely be more lossy on the pass > and the notches wouldn't fall into place. (isn't that what he's complaining > about?) > > This is why I hate the reference (especially on a 2 meter duplexer) of > Transmitter and Receiver ports, as HPLR and LPHR always make sense, no > matter frequency or orientation of the repeater split. > > > > > > > As I understood all the cavities are the same or are there two types? > Two types, HPLR and LPHR.... > > > > > Also we have made our only cables to join the units together using RG214. > I'm assuming all the cables should be ¼ taking into account the velocity > factor or the cable? > The cabling might have to be changed to optimize the notch depths, but he > needs to get a little closer before worrying about that. > > > > > > > > Bob > > > > -----Original Message----- > From: Repeater-Builder@yahoogroups.com > [mailto:[EMAIL PROTECTED] On Behalf Of > Kevin Custer > Sent: 03 June 2005 12:51 > To: Repeater-Builder@yahoogroups.com > Subject: Re: [Repeater-Builder] Help with Wacom WP-639 Duplexer > > > > > > m1ror wrote: Hello All > > This is my second posting but I'm not sure if my first attempt made it > to the list. > > I bought a set of what appear to be good condition Wacom WP-639 (144- > 174Mhz) Duplexers originally tuned for 156Mhz. A friend has attempted > to align the filters but is having problem aligning the notch down to > 145Mhz. > The problem he tells me is he can only get the notch down to 148Mhz > with the Invar rods pushed all the way in. He has made up new patching > loom and still the same result. > Has any body played with these and could offer any advice? > > > > Have him swap the ports and try again, in other words, tune the duplexer > backwards from the way it is presently tuned using the opposite sides for > the receiver and transmitter. Minimum frequency separation happens with the > rods all the way in, which leads me to believe he is attempting to tune the > duplexer upside down, on the 'wrong' notch; there are two notches, as > explained below.... > > This article explains the basic principal for the Wacom WP-641 and 639 > style pass notch network. While specifically written about the 641, the > effects are the same for the 639, however, the notch depth won't be as deep > with the 639 as what is stated in the article: > <http://www.repeater-builder.com/wacom/wacombpbrnotes.html> > > Complete tuning directions are available from this page: > <http://www.repeater-builder.com/wacom/wp6xxVHFtuninginstructions.pdf> > > If you still encounter difficulty after attempting the switch-a-roo, email > us back.... > > Kevin > > > > > > > ________________________________ > 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 the Yahoo! Terms of Service. 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/
