VA3TO 76/78GHz Portable Station




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Equipment details:

Dish: MTI MT-799002 - 12" Prime focus with integral Cassegrain feed.
Transverter: DB6NT/Khune MKU 76 G2 transverter. 200mW o/p power with internal LNA.
Local Oscillator DB6NT/Khune 8-13 L.O. + CTI 10 MHz OCXO reference. Switchable for 76 or 78 GHz operation.
LNA: Internal 23dBg, 7dB NF.
Waveguide Switch: Hughes manual WR-15 WG switch custom motorized using a stepper motor.
I.F. Rig: Icom IC-705 @ 144 MHz.


Accomplishments to date:

Best DX (Tropo): 167km - VA3TO in grid FN03df to VA3ELE in grid FN13ax.

78 GHz VUCC: 6 Grids from FN03cn: FN03, FN02, EN93, FN04, EN92 & EN94.



In the spring of 2023 I purchased an MKU 76G2 transverter and an 8-13 L.O from Khune in Germany. Finding affordable surplus equipment for this part of the radio spectrum is normally quite difficult but I was lucky enough to purchase a spare 70 GHz 12" dish with integrated feed and a manual Hughes WR-15 waveguide switch from my good friend Rene VE2UG. I was originally planning to use the waveguide switch manually then chose to try motorizing it. I first considered using a DC motor with microswitch limit switches but decided to try a stepper motor instead. I had to learn how they work so I bought a couple of different stepper motors off of Amazon along with an A4988 stepper driver board and an Arduino Nano microcontroller to experiment with. It turns out that the A4988 driver board simplifies the hardware interface and software required to run the stepper motor, so I was away to the races. I designed a custom carrier board for the Nano microcontroller and the A4988 stepper control module, wrote some code and it works very well. Detailed description in a document on this page: Motorizing a Manual Waveguide Switch using a Stepper Motor and a demonstration of the completed assembly in this video: Stepper motorized WR-15 Waveguide Switch in use.




First Tests on 78 GHz:

My first contact on 78 GHZ was with Kevin VE3KH. He was located in FN03CG and I was set up at Burloak Park (Burlington, Ontario) at a distance of 10 km. It was an easy contact with S9+ signals at both ends.


Updates:

- In the Spring of 2023 I set up in grid FN03fo at Samuel Smith Park (Mississauga, Ontario) to try a contact with Kevin VE3KH in FN03cg at a distance of 41 km. Video here: VA3TO FN03fo to VE3KH FN03cg ~ 41km on 78 GHz


- On April 15, 2024 I increased my personal best distance on 78 GHz to 71 km. Peter VA3ELE just finished working in the Niagara area and headed over to FN03jf at Sunset Beach on Lake Ontario near the mouth of the Welland Canal. I set up on a South-East facing edge of the Niagara Escarpment at FN03an on St.Helena Rd. just north of Milton, Ontario. I was using a 12" dish and Peter was using a pair of horns mounted directly on the transverter. We first completed using CW then repeated the contact using SSB (voice). Video here:   VA3TO FN03an to VA3ELE FN03jf ~ 71km on 78 GHz


- Grid #2 !
On October 15, 2024 Peter VA3ELE was working down in the Niagara region. There were some small isolated rain cells moving through the area so he drove down to FN02ax after work. We started off on 24 GHz to get an idea where to aim. Signals were pretty good on 24 GHz so we switched over to 78 and boom !!!... there he was. My first taste of 78 GHz rain scatter and my second grid. Proof that rainscatter does work on 78 GHz so that gives us confidence that we can achieve VUCC without perfect Line-Of-Sight paths. I was a little unprepared so I only caught the last part of our QSO... Video here:   VA3TO FN03cn to VA3ELE FN02ax ~ 78 GHz Grid #2
Peter's video:  78 GHz Grid #2 from Peter's end.


- Grid #3 !
On November 04, 2024 there was some low ceiling scattered rain in the forecast for our area so Peter VA3ELE messaged me and proposed that we do some testing on 78 GHz. After work he went to his chosen 78 GHz VUCC site at FN03dp and I drove to a roadside location in grid EN93xo, just a little bit north of my home in attempt to give him grid #2 on 78G. We lined up on 24 GHz with good signals then switched to 78 GHz. Nothing was heard on 78G so we went back to 24G to re-peak on the rain. After a bit of back and forth we found each other with decent signals on 78G and completed a QSO.

Since that worked out for us, Peter drove up to grid EN93xo and I drove down to my VUCC site at grid FN03cn to see if I could get the grid. In the meantime the rain that we used in the earlier contact dissipated but the weather radar was showing that more scattered rain was moving in. Once Peter arrived at the same location from where I worked him, the traffic had picked up so he decided to look for a quieter location. After a bit of driving around he found a site with a clearing in my general direction. The second wave of rain had not yet arrived but it was getting dark so we thought that we'd try a tropo shot. We set up and peaked up on 24 GHz with signals well into the red, It seemed promising for 78 GHz so we switched over and found each other within seconds of dashing. After peaking up on each other the signals were also very strong so Peter suggested that we go directly to FM and we completed the QSO in short order. Video here:   VA3TO FN03cn to VA3ELE EN93xo. 78 GHz Grid #3

Peter got all of it on video so you can see it from his end here:  78 GHz Grid #3 from Peter's end.


- Grid #4 !
On November 09, 2024 Peter VA3ELE drove up to operate from Grid FN04fa for our deferred November Microwave Activity Day. I set up at my favorite location on a train overpass at FN03cn. It was a nice sunny but chilly morning at 0°C. I first worked him on 10, 24 & 47 GHz via tropo then switched over to 78 GHz and it wasn't long before we found each other and completed a CW contact. Signals actually improved after our initial QSO so we repeated it on SSB. I also work Kevin VE3KH in FN03cg on all 4 bands. Video here:   VA3TO FN03cn to VA3ELE FN04fa. 78 GHz Grid #4


- Grid #5 ... 78 GHz VUCC !
On November 19, 2024 Peter VA3ELE was working down in the Niagara area. There was a bit of rain and the traffic was brutal as he started making his way home so he phoned to ask if I was up to try for my Grid#5. Of course I was game so he took a detour and drove an hour west to grid EN92xx. I drove over to my VUCC spot at FN03cn. The path was not ideal so we were hoping to do this by rainscatter, but the rain had already passed by the time he arrived on site. In fact it was drizzling at my end while I was setting up. The humidity was in the 90% range, and the wind had really picked up so I was not feeling very optimistic at all but as we've learned in the past, just try it ! We started off on 24 GHz to get the bearing, peaked up on each other then switched over to 78 GHz. I aimed my 78 GHz dish in the same general direction, panned around a little and within a minute or so found Peter's dashes on the bandscope, so I tuned him in and heard him well enough to complete the QSO.

Video here:  VA3TO FN03cn to VA3ELE EN92xx. Grid #5 for 78 GHz VUCC !    It didn't record very well due to the wind and road noise but I heard it just fine.

Video from Peter's end here:  VA3TO 78 GHz Grid #5 from Peter's end.



- 167 km on 78 GHz ... New Canadian 78 GHz DX Record !
On the morning of April 18,2025 I drove to grid FN03df at a lookout point off Ridge Road on top of the Niagara Escarpment at the west end of Lake Ontario near Hamilton, Ont. Peter VA3ELE drove east, first to a favorite lakeside park of ours off Monk St. in Cobourg, Ont., grid FN03vw where we easily worked on 24 & 78 GHz @ 150km. Video here:  VA3TO FN03df to VA3ELE FN03vw ~ 150km on 78 GHz

Then Peter drove a litte further east to FN13ax at the Wicklow Boat Launch, just east of Grafton, Ont. where he first worked Kevin VE3KH at 166km, a new grid for him on 78 GHz. Congrats Kevin !
Then it was my turn and again, we completed on 24 & 78 GHz, this time at 167 km. Both contacts were made in CW and SSB and even heard each other on FM. Deep QSB (fading) on 78 GHz at those distances due to variations in the air density over Lake Ontario. I was not at my home grid so no new one for me.
Video here:  VA3TO FN03df to VA3ELE FN13ax ~ 167km on 78 GHz


- Grid #6 !
On the afternoon of May 04, 2025 Peter VA3ELE had some work to do up near Orangeville, On. There was scattered rain between us so after he finished his job he drove up to grid EN94wb to see if I could get a new one on 78 GHz from my VUCC location at FN03cn. There's a rise in terrain where the Oak Ridges Moraine meets the Niagara Escarpment inbetween this path, so it's definitely not Line-of-Sight. Any chance for a successful contact would need to be attempted using rainscatter, so this was a good opportunity to try. First we lined up on 24 GHz to get the bearing with very stong signals, then we switched over to 78 GHz. Signals on 78 GHz were far weaker so we had to work at peaking each other up. After a bit of dashing back and forth we had enough to work with and completed a CW rainscatter contact !
Video from Peter's side here:   VA3TO FN03cn to VA3ELE FN04fa. 78 GHz Grid #4




75 GHz VUCC (6 Grids).










78 GHz Grids Worked from FN03CN
(Tropo contacts = Yellow dot, Rain Scatter contacts = blue dot.)




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