Hi Eric, The link didn't work for me either,
73 de Mike ei2dj / g4gxn --- In [email protected], "Eric Lemmon" <wb6...@...> wrote: > > Norm, > > That's really odd- the link works fine from both home and work computers. > Nevertheless, I have sent you the file directly. > > 73, Eric Lemmon WB6FLY > > > -----Original Message----- > From: [email protected] > [mailto:[email protected]] On Behalf Of NORM KNAPP > Sent: Monday, July 13, 2009 11:09 AM > To: [email protected] > Subject: Re: [Repeater-Builder] Notch on duplexers... How low should they > go??? > > > > Hi Eric > Sorry to bother you, but the link for the harness drawings didn't work. Can > you e-mail to me or can I not find this info on the repeater builders web > page? > Thanks. > De N5NPO n5...@... <mailto:n5npo%40hotmail.com> > Norm > > ----- Original Message ----- > From: [email protected] > <mailto:Repeater-Builder%40yahoogroups.com> > <[email protected] > <mailto:Repeater-Builder%40yahoogroups.com> > > To: [email protected] > <mailto:Repeater-Builder%40yahoogroups.com> > <[email protected] > <mailto:Repeater-Builder%40yahoogroups.com> > > Sent: Sun Jul 12 11:01:30 2009 > Subject: RE: [Repeater-Builder] Notch on duplexers... How low should they > go??? > > > > Norm, > > The tuning rods on the TX pair of cavities will be at different heights than > > those on the RX pair, simply because they are tuned to different > frequencies. As for the RG-142 jumpers, that's okay because RG-142 is > double-shielded. Changing those jumpers to RG-214/U will probably gain you > nothing. If those jumpers are the right lengths, I'd leave them alone. > > A while back, I set up a Q202G duplexer for a local radio club. It was > originally tuned to a commercial pair in the 152-157 MHz band, so I asked > the club to purchase a low-split harness from Sinclair. When the new > harness arrived, I took careful measurements of both the new and the old > harness, and the results are on a drawing I posted in the Files section, > here: > <http://tinyurl.com/l3xquy <http://tinyurl.com/l3xquy> > <http://tinyurl.com/l3xquy <http://tinyurl.com/l3xquy> > > > > If the harness on your duplexer is the high-split version, with about 12 > inches between tee centers, you will not be able to achieve optimum tuning. > The factory-made harness uses Delta crimped connectors, and costs about > $250. If I were to do this again, I would consider fabricating the harness > myself, with genuine Delta tees, which can be purchased for a total of > around $120. > > 73, Eric Lemmon WB6FLY > > -----Original Message----- > From: [email protected] > <mailto:Repeater-Builder%40yahoogroups.com> > <mailto:Repeater-Builder%40yahoogroups.com> > [mailto:[email protected] > <mailto:Repeater-Builder%40yahoogroups.com> > <mailto:Repeater-Builder%40yahoogroups.com> ] On Behalf Of NORM KNAPP > Sent: Sunday, July 12, 2009 8:46 AM > To: [email protected] > <mailto:Repeater-Builder%40yahoogroups.com> > <mailto:Repeater-Builder%40yahoogroups.com> > Subject: Re: [Repeater-Builder] Notch on duplexers... How low should they > go??? > > Ok Eric, > You just brought up something... > My cans are SANS cabinet. Two of the cans at least, have serial numbers and > model numbers on them. I am seriously now thinking that this is a > Frankenstein monster duplexer made from cans from more than 2 set. The > tuning rods on the one pair have slightly different adjustment/hold it in > place fixtures. Furthermore, the harness is made from RG-142. Very nicely > done, but I am thinking non-stock never the less. I have some good RG-9 and > some RG-214. Perhaps I should build a new harness. > I got -79 on the lo pass (tx) side and about -85 on the hi pass (rx) side as > > it sits now. > Tnx > De N5NPO > Norm > > ----- Original Message ----- > From: [email protected] > <mailto:Repeater-Builder%40yahoogroups.com> > <mailto:Repeater-Builder%40yahoogroups.com> > <mailto:Repeater-Builder%40yahoogroups.com> > <[email protected] > <mailto:Repeater-Builder%40yahoogroups.com> > <mailto:Repeater-Builder%40yahoogroups.com> > <mailto:Repeater-Builder%40yahoogroups.com> > > To: [email protected] > <mailto:Repeater-Builder%40yahoogroups.com> > <mailto:Repeater-Builder%40yahoogroups.com> > <mailto:Repeater-Builder%40yahoogroups.com> > <[email protected] > <mailto:Repeater-Builder%40yahoogroups.com> > <mailto:Repeater-Builder%40yahoogroups.com> > <mailto:Repeater-Builder%40yahoogroups.com> > > Sent: Sun Jul 12 10:19:54 2009 > Subject: RE: [Repeater-Builder] Notch on duplexers... How low should they > go??? > > Jeff, > > I agree completely with your conclusions. When tuned on my vector network > analyzer, I have often been able to achieve 90 dB of isolation on both sides > > > of a Sinclair Q202G duplexer at 2m. The key to getting this kind of > performance is not just tuning each can individually for optimum return > loss, but also ensuring that each pair of cavities is matched to its > partner- something that a network analyzer does very well. Of course, this > assumes that the low-split harness with 14 inches between the tee > connectors, is installed. One of the quirks of the Q202G duplexer is that > the stickers (or dots) that Sinclair puts next to each loop plate may not be > > > exact, but only approximate. With a network analyzer, the loops in each > cavity can be adjusted so that they are electrically symmetrical. This is a > painstaking process, but it results in optimum tuning. > > The GE isolation curves Jeff mentioned are found in the Service Bulletin > section, here: > <www.repeater-builder.com/ge/lbi-master-list.html> > > 73, Eric Lemmon WB6FLY > > -----Original Message----- > From: [email protected] > <mailto:Repeater-Builder%40yahoogroups.com> > <mailto:Repeater-Builder%40yahoogroups.com> > <mailto:Repeater-Builder%40yahoogroups.com> > <mailto:Repeater-Builder%40yahoogroups.com> > [mailto:[email protected] > <mailto:Repeater-Builder%40yahoogroups.com> > <mailto:Repeater-Builder%40yahoogroups.com> > <mailto:Repeater-Builder%40yahoogroups.com> > <mailto:Repeater-Builder%40yahoogroups.com> ] On Behalf Of Jeff DePolo > Sent: Sunday, July 12, 2009 7:51 AM > To: [email protected] > <mailto:Repeater-Builder%40yahoogroups.com> > <mailto:Repeater-Builder%40yahoogroups.com> > <mailto:Repeater-Builder%40yahoogroups.com> > <mailto:Repeater-Builder%40yahoogroups.com> > Subject: RE: [Repeater-Builder] Notch on duplexers... How low should they > go??? > > With a preamp, if you're only getting -106 dBm sensitivity, something is > wrong. If memory serves, the spec for 12 dB SINAD without the preamp for a > highband Mastr II is 0.35 uV (-116 dBm), and with the UHS preamp the > sensitivity was 6 dB better (-122 dBm). > > Looking at the GE isolation curves, for a 100 watt highband transmitter with > > > a phase-modulated exciter you need a minimum of 81 dB of noise supression > (Tx cavity notch depth) and 69 dB of carrier supression (Rx cavity notch > depth). For the PLL exciter, you only need 59 dB of noise supression. GE's > curves are based on the assumption that 1 dB degradation (desense) is > acceptable. > > If you add the UHS preamp, GE recommends adding another 6 dB to both > isolation requirements. Personally I think that's cutting it rather close. > The preamp has about 10 dB gain, but its noise figure isn't very good, hence > > > the usable improvement in sensitivity is only about 6 dB. But that 10 dB of > gain is still there, so you want at least 10 dB more carrier supression to > prevent receiver overload (at least that's the way I look at it). > > On top of the calculated minimums, I always want to see AT LEAST 10 dB more > isolation than the minimum required, more if I can get it. > > So, assuming you're using a regular PM exciter, 100 watt PA, and UHS preamp, > > > if I were building the box I'd be targeting 100+ dB of noise supression and > 90 dB of carrier rejection at a minimum. > > --- Jeff WN3A > > > -----Original Message----- > > From: [email protected] > <mailto:Repeater-Builder%40yahoogroups.com> > <mailto:Repeater-Builder%40yahoogroups.com> > <mailto:Repeater-Builder%40yahoogroups.com> > <mailto:Repeater-Builder%40yahoogroups.com> > <mailto:Repeater-Builder%40yahoogroups.com> > > [mailto:[email protected] > <mailto:Repeater-Builder%40yahoogroups.com> > <mailto:Repeater-Builder%40yahoogroups.com> > <mailto:Repeater-Builder%40yahoogroups.com> > <mailto:Repeater-Builder%40yahoogroups.com> > <mailto:Repeater-Builder%40yahoogroups.com> ] On Behalf Of AJ > > Sent: Saturday, July 11, 2009 10:00 PM > > To: [email protected] > <mailto:Repeater-Builder%40yahoogroups.com> > <mailto:Repeater-Builder%40yahoogroups.com> > <mailto:Repeater-Builder%40yahoogroups.com> > <mailto:Repeater-Builder%40yahoogroups.com> > <mailto:Repeater-Builder%40yahoogroups.com> > > Subject: Re: [Repeater-Builder] Notch on duplexers... How low > > should they go??? > > > > > > > > In my instance here... > > > > Factory preamp puts you around -106 dBm sensitivity which at > > 44 dBm tx works out to needing about 91 dB of isolation at my > > 600 KHz split... You, however, have 50 dBm so you're looking > > at closer to 96 dB of isolation to sit at theorhetical zero > > desense. I'm sure someone on here can run the numbers through > > Commshop - stock VHF RX with 10 dB preamp is around .18 uV > > sensitivity. > > > > I'm just coming off a 13 hour shift so my math may be (way) off lol :) > > > > -AJ, K6LOR > > > > On Sat, Jul 11, 2009 at 7:46 PM, NORM KNAPP > > <nkn...@... <mailto:nknapp%40twowayradio.net> > <mailto:nknapp%40twowayradio.net> <mailto:nknapp%40twowayradio.net> > <mailto:nknapp%40twowayradio.net> <mailto:nknapp%40twowayradio.net> > <mailto:nkn...@... <mailto:nknapp%40twowayradio.net> > <mailto:nknapp%40twowayradio.net> <mailto:nknapp%40twowayradio.net> > <mailto:nknapp%40twowayradio.net> <mailto:nknapp%40twowayradio.net> > > > wrote: > > > > > > > > > > I was checking the tuning on my duplexers for the > > 147.225 repeater after noticing some desense on with the > > service monitor. I had something like 99 watts going into the > > duplexers (sinclair Q-202g) and about 85 coming out. I > > thought, WOW! This cannot be right. Sure enough they were > > aparently mis-tuned. I switched the service monitor into the > > tracking gen mode and began. The rx side was pretty close and > > when I got done I had a -85db or so notch at 147.225mhz. All > > I had to do was move the ol' notches with the little caps > > next to the connector. The pass at 147.825 looked good, about > > -1.5db or so. Moved over to the TX side (low pass) and the > > notches were off. A good bit off in fact. So I startes tuning > > them to where they needed to be and all I could get was about > > -65db or so. What gives?!? Oh no, I thought. I am gonna have > > to spin the loops! EGAD!!! I hate doing that. Oh well, here > > goes nothing. I isolated the first jug and began spinning. I > > ended up getting it (one jug) down to about -31db. The other > > side were in the -35db or more area. Try as I may the -31db > > per can was about as good as I could get. Whith both cans > > together I get a -79db notch on the 147.825 rx frequency with > > about -1.4 db on the pass. Is this adequate for a MASTR II > > with the factory preamp? The desense is pretty much gone now. > > I think if I spent a little more time I could probably get > > the notch a little closer to the -85db that I got on the > > other pair on the high pass rx side, but I am not sure it is > > worth the effort. > > What do you thing guys??? > > > > 73 de N5NPO > > > > > > > > > > > > Checked by AVG - www.avg.com > > Version: 8.5.375 / Virus Database: 270.13.12/2233 - Release > > Date: 07/12/09 08:20:00 > > > > > > >
