Hi Skipp, Was hoping for the rest of your comments (after lunch), but in the mean time here are some responses to this first set. Thanks.
Alex --- In [email protected], "skipp025" <[EMAIL PROTECTED]> wrote: I'd probably Cut the repeater power output > down a bit. Since you have narly antenna gain, > I'd probably back the repeaters down to 80 > watts to possibly improve the unwanted products > from the power amplifiers (which can be measured). We tried lowering the power as far a 25W, and the interference was always still present. In view of that power was again set at 100W. Still I would agree that lowering it to 75-80W would help somewhat once additional filtering is installed, without affecting coverage too much. > Did you check the combiner for proper tuning? All > is rarely plug and play in the real world. "Trust > but verify". Did not. Assumed it was Ok, and was not sure that something else besides the pass cavities would need to be retuned (isolators?), so left it alone. Guess only the cavities need to be checked for maximum power transfer? If so will do that as part of the to-do list when we return to the site. One thing I did notice on the combiner is that one of the dummy loads on the CH1/control channel isolator (the one closest to the input) was getting quite hot to the touch. The other load on the same isolator was only getting warm. Since these are basically terminated on N-connectors I hooked up a wattmeter, but it was only showing 3W (as I recall the load is rated at 35W). Left it as is for a while and it turned out the heat was actually coming from the isolator, not from the load. Is this normal? This was happening with just CH1 transmitting (continuously). > > > (Cavity/Dual Isolator type), and a Sinclair > > RM201-112S1B RX Multicoupler fitted with a BP > > Preselector (with 1MHz pass-band, and factory > > tuned to 165.625), a "Hi Level" Bipolar preamp > > (Angle Linear brand / anglelinear.com), > > Crap, I just took a look at it. > Not enough protection... by a long shot. You need > to boot the 1 MHz band pass filter and get a real > serious vhf preselection network. Was considering changing the Preselector to a pass-reject type, and have it tuned for maximum rejection to where the TX carriers are. But I am still trying to locate a drop-in replacement of this kind, if available at all in that "compact surface mount" type. Or will I need to get one with bigger cavities? Suggestions? > > As mentioned before, you should also add some > serious receiver protection in the transmit > combiner side/path. You mean of course the notch filters. Can you suggest a specific model/brand? One you would use in your own system under the same circumstances. > Using 6 ports..? Every other coax jack should be used > to balance the internal dividers better and "mo > isolation". So I would use ports 1-3-5-7-9-11 ? Or 2-4-6-8-10-12? > > > Between the preamp output and the power divider there > > is a 2dB pad fitted. > Not good, the horse is already out of the barn... Isn't this pad used to keep the overall gain of the Preselector at zero positive gain? It was factory installed. Of course, if I have to change the Preselector, obviously this would very likely also have to be changed. > If the site is on a hill, you might do better with a bit more > vertical seperation trade. Lower the tx antenna if possible. > Increasing the vertical seperation from 45' to say... 65' will > help a lot. Nope, perfectly flat terrain all around. I've gotten the more antenna separation suggestions from others, only problem is that the tower is only 90ft, and antennas are about 40ft each in length. so not much room for separation. As it is they are already very close to each other. One thing we tried (and was also recently suggested) is to split up each DB228 into separate DB224's. We used the upper portion of the top most antenna, and the lower portion of the other. That increased the separation between the two active antennas to about 40Ft. Still the interference was present, did no seem to help much, so we hooked all up again as it was. Parallel as in right next to each other? A big no-no even > for 7/8 Hardline. The two lines had better be min 6 inches > away from each other in the the inbound tray. Yes, separating these two will also be on my to-do list. > > Combiner to repeater TX port jumpers are made of Belden 9913, > From Telewave..? or you made them up? You need to boot the > 9913 and use RG-214 min or 1/2 inch superflex hardline typical. We made them. Will use RG214, as 1/2 (even superflex) will be a bit of a pain to fit. >Crap... boot the RG-58 right away. There is no real 100% > shielded rg-58 that I've ever measured. We are now using RG142 jumpers on the RX jumpers. There is not much spacing between the output ports of the multicoupler, so fitting RG214 in there would be a bit tricky. > Not good enough... did you use any main signal notch cavities > with the test set up described below? You are not going to see > the problem using what you describe above. No, just hooked up the spectrum analyzer into the TX path with a Lossy T adaptor. Disn't have anything else handy. > Lunch takes me away (I like to eat)... more later on. Bon Apetit. > > cheers, > skipp 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/
