This past weekend I met three other hams at the Synopsys site in Hillsboro to install our group’s D-STAR repeater.\u00a0 We have had the components of this stack for a while now and have been testing it at a low-level site (my house).\u00a0 Late last year, a member of our group approached the Synopsys facilities supervisor about potentially locating some or all of our D-STAR repeater equipment on their roof.\u00a0 They graciously agreed and we closed on that this weekend.<\/p>\n
We installed a Comet GP-98 antenna on a ten-foot pole with a very short run of 9913 coax through the wall into the roof stairwell enclosure.\u00a0 Inside, we put a 7′ fully-enclosed rack cabinet with our D-STAR repeater controller, UHF RF module, and our UHF duplexer cans from TX\/RX Systems.\u00a0 We got everything installed and set out to test things to make sure they worked properly.<\/p>\n
Initially, we were getting almost no power output from the repeater past the duplexer, but full output into a dummy load.\u00a0 Not looking to prolong the installation day too far, we decided to tune up and install a small mobile notch duplexer that I happened to have with me so that we could at least get the machine on the air and then go home and diagnose the issue with the large duplexer offline.\u00a0 Performance with the notch was not good at all, and I was worried that there were other issues at play.\u00a0 Anything but the strongest signals into the repeater were seriously garbled and absolutely no data traffic was making it through the unit.<\/p>\n
At home, we were able to determine that while the duplexer cans were tuned perfectly for our transmit frequency, they were presenting a relatively high SWR to the repeater PA, which caused it to scale back its power dramatically (from about 20W to 2.5W or so).\u00a0 We retuned the duplexer a bit to give an additional 1db of loss but with very low SWR.\u00a0 I tested it on a ground-level repeater module and confirmed that it was putting out reasonable power again.<\/p>\n
On Wednesday, I returned to the Synopsys site to reinstall the better duplexer and do a little bit of testing.\u00a0 With a wattmeter, I was able to confirm that the repeater was putting out a reasonable amount of power after the duplexer.\u00a0 After calling on the air for testers, it was immediately apparant that it was performing significantly better with the cans than the notch filter.\u00a0 More testing that day and the day after was extremely positive.\u00a0 Mobile stations were getting into the repeater quite well, and almost all fixed stations could hit it easily at 5W, even with a handheld on a rubber duck.\u00a0 Wednesday night, I was able to have a QSO *and* transmit GPS position reports clearly from PDX Airport some 18 miles east.\u00a0 Thursday morning, another station was able to get into the repeater easily while mobile from the intersection of Highway 6 and Highway 8, about 20 miles west.\u00a0 Quite impressive for a repeater that is only six stories off the ground and putting out about 15 watts after losses!<\/p>\n
The machine is KD7RFI_B on 440.550+MHz.\u00a0 There is no gateway on it (and we’re not sure if we will try to install one at this site or not) at the moment.\u00a0 If you’re within range, jump on and say hi! <\/p>\n","protected":false},"excerpt":{"rendered":"
This past weekend I met three other hams at the Synopsys site in Hillsboro to install our group’s D-STAR repeater.\u00a0 We have had the components of this stack for a while now and have been testing it at a low-level … Continue reading