On Tuesday 12/08 Ray Uberecken and Bill Miller traveled to the Plishner site. We found that the gate chain lock was not properly attached to the post and could be removed without unlocking it
We replaced two of the coaxial cables running from the dish pedestal control deck to the upper deck just below the dish. These cables had stretched from their own weight and from the elevation rotation of the dish. As a consequence the center pin pulled out from the mating connector, losing the conductivity. We added to the cable a loop over the elevation axis. Ray added a feedthrough connector attachment on the ceramic slip ring collar, in order to remove the rest of the hanging stress on the wires, and he re-added the swivel joints below that. This arrangement completely eliminates the cables traveling up and down thru the collar as the elevation is changed, and this also virtually eliminates the coaxial cable wrap in the control deck area. We redressed all of the cables there with tie wraps and tape to get them out of the way of personnel in the deck and to remove the mechanical strain on all the cables.
At the top deck we removed the AC extension cord, which had been temporarily installed to a power amplifier at the feed for EME. Its cord insulation might not have survived the winter, and the uninsulated cord could potentially short out to the structure. A more permanent and reliable 120 volt power distribution is needed to the feed point.
We also re-dressed all the wires and coax cable in the upper deck. We reused the pipe grommets as a weather shield for the cables going down thru the azimuth axes collar to the control deck level.
We then placed a ladder on the mount and proceeded up to the dish surface. There we continued to remove the 120 volt extension cord, and we inspected the surface and the support. This is a wide angle shot of the scene in the dish. It does give a sense of the surreal feeling of the view from there.
We inspected the attachments and connections. We discovered that the grounding cable connection on one of the legs leading to the focal box had been cut off. Furthermore, the wave guide that is attached at the dish structure is not electrically attached to the focal point box. Therefore the only ground to protect from RF, lightning, or static is the coax shield and the low voltage control cable ground wire. This may be one of the causes of failures in the electronics. We should retrofit to provide a good DC ground connection between the feed box at the focal point to the pedestal.
We also wanted to know how the fiber glass supports for the feed are adjusted.
The fiber glass supports are badly weathered after 60 years in the open. We should derive a plan to rework the fiberglass surface, for the next time we rent a bucket lift to work on them.
Once we had inspected the dish, we tipped the dish down to the service elevation, donned climbing harnesses, and climbed the scaffold tower. We removed the 1296 MHz feed and installed the 408MHz antenna using Ray’s quick-change mount. This only took about an hour where before the process could take as much as half a day.
We also reworked the connector attachments in the electronics box. Ray then reattached the additional 20db amplifier, and checked everything out with the TDR and Spectrum analyzer. He reattached the cables in the pedestal to connect the correct coax lines to the Comm. Trailer.
Bill replaced the broken window in the back of the comm. trailer with the new one he purchased from Kent Glass and sealed it with RTV. This provides a much clearer view of the dish from the trailer.
We parked the dish, turned off all the equipment, locked the site and left for the day.
On the weekend following this past Thanksgiving we participated in the second round of the ARRL EME Contest, which ran for 48 hours, on November 28 & 29, 2020, GMT hours. This time it was a cliff-hanger in that we almost didn’t get on the air. But with some dedicated effort we succeeded again. This time we contacted some new places. And we added JT65C digital mode.
Team members for this operation were Ray Uberecken AA0L, Gary Agranat WA2JQZ, Myron Babcock KL7YY, and Bill Miller KC0FHN. Floyd Glick WD0CUJ came out also for one evening, accompanied by our new member Michael Nameika.
For this weekend the Moon was at almost full phase. That meant that it would be up mostly during our nighttime, which therefore was when we would have to do our operations. The contest would start at 0000 Hours GMT, which for us was 5 PM on Friday evening November 27. The Moon was already rising at 3:19 PM, so it would be up high enough to begin operating right away, once the contest started.
Ray and Bill arrived Friday afternoon by 3 PM to set up and do last minute testing. I (Gary) arrived soon after.
In our testing, we found we could receive the 1296 MHz beacon Ray set up at his home in Peyton. But we couldn’t properly transmit.
We quickly slew the antenna to the service tower, and Ray retrieved the amplifier at the feed. The thinking was the problem might be there.
Ray did some quick testing of the amplifier. But an initial check didn’t find anything wrong.
Ray then climbed back up the tower to return the amplifier to the feed point. We thought about what else could be wrong.
We then checked how much power was being drawn by the amplifier in the pedestal. The power meter was reading about 30 Watts when we tried to transmit, when it should have been reading about 200 Watts. At that point the sky was getting dark. It would not have been safe to do any more climbing. And so for the first night of the contest we couldn’t operate.
Bill returned home, but was available the next day for coordination in Colorado Springs. Ray and I spent overnight at the site, to continue troubleshooting on Saturday. We would have the whole day in sunlight, until the Moon rose for the second pass at 3:47 PM.
Before going to sleep I (Gary) made some HF ham radio contacts. So we got on the air still, but on HF. This weekend there was also another contest, the CQ World Wide CW (Morse Code) Contest. On 160 and 80 meters I made three contacts with Canadian stations. There were lots of US stations on, but for the rules of this contest, you have to contact stations outside of your country (or more precisely outside of your DX area, which for us is the CONUS). I afterwards made some HF FT8 digital contacts for the club, on 80 and 40 meters. On 40 meters we made our first DX contact with New Caledonia in the southwest Pacific, with station FK8HM. This was with our recently repaired vertical antenna, so this showed our vertical was working OK.
Early the next morning I made some more CW contacts for the contest, this time on 40 meters using the vertical, and on 15 meters, using both the vertical and Yagi antennas. On 40 meters, while it was still dark across the Pacific, stations in China, Hong Kong, and South Korea were heard, but I didn’t succeed in making contacts. I did succeed though in contacting two Japanese stations. Then on 15 meters, with daylight across the Atlantic, the band was wide open to Europe. For a few minutes while on the air, we made contacts with France, Spain, and Slovenia, and also one contact to the south with Brazil.
Ray and I had breakfast and resumed troubleshooting work at 9 AM. We retrieved the amplifier again, and this time did a much more thorough test. Ray found one diode was leaking current. But this was a circuit safety issue and not a showstopper for transmitting. Ray replaced the diode, and returned the amplifier to the feed.
We then considered what else could cause our problem. Ray tested the conductivity of our feed lines. We have two coax cables running from the operations trailer to the feed. Ray climbed to the feed, and connected the two cables there. Then we measured the conductivity going out and coming back, together at the same time. His software analyzer showed Coax cable #1 had a fault at 135 feet down the line, and Coax cable #2 had a fault 185 feet down the line. This corresponded with where there are swivel joints for the cables, where the fixed pedestal interfaces with the moving dish antenna structure. A signal test also showed there was more loss on the lines then expected.
At first Ray wondered that the swivel joints might be the problem. However, on visual inspection those were seen to be OK. The problem was eventually traced instead to the weight of the cables at that location pulling on the centers of the feeds, causing those to slip out.
Ray was able to repair Feed Line #1. We then did more testing, with Ray’s beacon and the W0TTT beacon in Como, CO, and with an SSB tropospheric scatter contact with Myron in the Springs, and found we were working well. We were back in business.
Myron drove out to the site, and operated with us the second night. While Myron was on his way, I slew the antenna for Moonrise, getting more practice with the System 1 automatic tracking.
As soon as the Moon rose we heard CW and digital signals. We again had to figure out the Doppler shift correction, using the WSJT 10 software. At the start we made several CW contacts with Europe: to Germany, England, Croatia, France, Poland, and Austria.
Eventually we also tried digital JT65C –for the first time. That was a learning curve, but we finally got it. One of the tricks for that was that the waterfall window on the JT65C has a bar at top designating where the sync pulse of the signal has to be, in order for the software to decode it. Another challenge was that operators were heard with JT65 weren’t using a consistent contact exchange format. And so I had to manually edit the exchange fields quickly, in the 10 seconds between decoding and transmitting.
We made 19 contacts altogether. 16 were with CW (Morse Code) and 3 were digital JT65C. Myron tried several times to make SSB contacts. But there were no takers to respond back to us.
Over the night, I generally made the CW and digital contacts, while Ray operated the radio, including keeping up with the Doppler shift offsets. I offered to let others make contacts too. But we were comfortable doing it this way.
Floyd came during the evening with his astronomy student Michael Namieka. Floyd showed Michael around the site, and I believe also made some HF contacts in the bunker. They watched our EME operation. They got into a good technical discussion about the component causes of the Doppler shifts. Myron had Michael send a voice CQ and test moon bounce signal, and Michael heard his voice come back about 2 seconds later.
Our CW contacts included our DSES member Skip, VE6BGT — he said we sounded much stronger this time. And we found several other stations we had contacted last month too.
On JT65 we had QSOs with AL Katz K2UYH, W6YX Stanford University, and AA4MD in Florida (who last month we got on CW).
New countries to Europe this time were France and Croatia. We got KL6M in Alaska, who built our feed. We got one Japanese contact JH1KRC, who we contacted last month. And this time we had one contact with Australia, VK5MC, probably our contact furthest away from us. I am happy to report we had pileups on us. At least some of our contacts already knew something about us and our capability.
This is a record of our contacts, from the Cabrillo formatted file we submitted to the ARRL for the contest. CW is Morse Code. DG is JT65C digital. 1.2 G is the 1.2 GHz frequency band. You see the date and times in GMT, our station with the signal report we sent, and the station we contacted with their signal report to us. QSO: 1.2G CW 2020-11-28 2312 K0PRT 599 DG5CST 599 Germany QSO: 1.2G CW 2020-11-28 2317 K0PRT 559 SP7DCS 589 Poland QSO: 1.2G CW 2020-11-28 2324 K0PRT 559 G4CCH 599 England QSO: 1.2G CW 2020-11-29 0007 K0PRT 559 9A5AA 579 Croatia QSO: 1.2G CW 2020-11-29 0020 K0PRT 569 DL6SH 579 Germany QSO: 1.2G CW 2020-11-29 0040 K0PRT 569 VE6BGT 589 Canada QSO: 1.2G CW 2020-11-29 0057 K0PRT 579 OE5JFL 579 Austria QSO: 1.2G CW 2020-11-29 0216 K0PRT 569 WA9FWD 579 Wisconsin, USA QSO: 1.2G CW 2020-11-29 0350 K0PRT 559 F2CT 569 France QSO: 1.2G CW 2020-11-29 0403 K0PRT 559 KL6M 579 Anchorage, Alaska, USA QSO: 1.2G CW 2020-11-29 0407 K0PRT 559 OK1KIR 569 Czech Republic QSO: 1.2G CW 2020-11-29 0413 K0PRT 559 I5MPK 599 Italy QSO: 1.2G CW 2020-11-29 0420 K0PRT 559 K7CA 559 Nevada, USA QSO: 1.2G CW 2020-11-29 0430 K0PRT 549 KA1GT 559 Maine, USA QSO: 1.2G DG 2020-11-29 0629 K0PRT -06 K2UYH -01 New Jersey, USA QSO: 1.2G CW 2020-11-29 0750 K0PRT 569 JH1KRC 589 Japan QSO: 1.2G DG 2020-11-29 0811 K0PRT -08 W6YX -08 California, USA QSO: 1.2G CW 2020-11-29 0920 K0PRT 439 VK5MC 449 Australia QSO: 1.2G CW 2020-11-29 0946 K0PRT 599 N4PZ 599 Chicago, Illinois, USA QSO: 1.2G DG 2020-11-29 1006 K0PRT -09 AA4MD -07 Florida, USA
We decided to stop operating at around 3:30 AM Sunday morning. We were hearing much fewer new contacts. But also the outside wind was picking up immensely. Forecasts for the region were for gusts up to 50 knots. We stowed the antenna back to the safe position. Ray, Myron and I then got sleep in the operations trailer. Outside the temperature dropped to the low 20s, but we kept warm inside with the heaters. Myron left early in the morning. Ray and I closed the site by 11 AM Sunday, and headed back to the Springs.
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Some technical feedback: System 1 was working almost perfectly. The one glitch again was that there was a discontinuity in elevation reading on Friday night as the elevation was brought close to zero (seen by Bill). I didn’t experience that on Saturday or Sunday. Otherwise, the System 1 is an immense help. It makes the slewing and tracking easy and seamless.
We had a learning curve figuring out all of the nuances and details (or the sufficient and necessary details) for running JT65. We did eventually get JT65 working well. You do need to pay attention to its peculiarities. It probably could use some guidance documents, like we have for System 1.
I will note I did try to make a number of contacts but didn’t get responses. I don’t know why that was. I am suspecting part of the reason might be due to not getting the Doppler shift offsets quite right at times. But we did get a number of good signal reports and explicit comments that we had good signals.
Later I did some research. One of our contacts KA1GT has some articles on the Doppler shift math and corrections. These might be helpful:
It was a somewhat intense weekend for the team — with not being able to operate Friday evening as it got dark, with the troubleshooting, the cold and windy weather conditions and staying overnight (for some for 2 nights) on site. But we were very pleased we got our Moon communications back. We had lots of good signal reports. We apparently were doing better than in October with our signals. We probably had fewer contacts than last time as we were spending time figuring out the JT65 and Signallink. And I suspect there might have been fewer hams on for the second night. But I think also we didn’t want to knock ourselves out, especially with all the work we did. We found a good balance that worked.
I think all of us involved were very pleased with what we accomplished this weekend. We spent the effort to troubleshoot, we got ourselves back on the air, and we made a successful second EME Moon bounce operation.