630m - The Path To VK

Roger, VK4YB

I've been exchanging e-mails lately with Roger, VK4YB, in Queensland, Australia.

Roger is located about 30 miles from the ocean and has been the only VK signal that I have been able to hear on 630m WSPR mode. He seems to have the strongest signal out of Australia on 630m with his 90 watts and 120' tree supported wire vertical. John, VE7BDQ, has been heard twice down under with his modest station running at the allowable 5W EIRP limit, being reported in the fall of 2015 and again this spring. As well, John has heard Roger, the only signal from VK that either of us has copied.

I would like to be able to run some schedules with Roger in the fall, when transpacific paths should peak again. With that in mind, construction has begun on a new 630m transverter that will allow me to drive my present FET amplifier at full EIRP. Our schedules will utilize the JT9 weak signal mode, similar to JT65 but designed for the noisier LF and MF bands. It uses about 10% of the bandwidth that a JT65 signal requires, about 15Hz, and gains about 2db more sensitivity. A two-way QSO, under the best conditions, would take four minutes if all went well. A typical exchange of the required information, if initiated at my end, would look something like this:

                    VK4YB VE7SL
                    VE7SL VK4YB -20
                    R -18
                    RR 73
               73 73 (not really needed but indicates RR received)

The path from my end is difficult as I am on the east side of Mayne Island and in Roger's direction, about one mile from a 600' hill directly in line with VK. Any RF heading Roger's way will need to leave here at a fairly high angle, which is likely the case anyway considering the low and short (in terms of wavelength) inverted-L antenna.

The path profile from here to the open Pacific Ocean is shown below, with my end being on the right edge, just behind those two hills. The rest of the obstructions are on Saltspring Island and then Vancouver Island, before hitting open water.

VE7SL To VK4YB courtesy: Hey What's That Path Profiler

The most consistent west coast signal to reach down under is from Larry, W7IUV, in Washington state, operating experimentally as WH2XGP. Larry's path is a little more forgiving although his inland location certainly doesn't help. His first obstacle is about 10 miles away and about 2,000' higher. I would guess that his signal is well above that before reaching those mountains and the remaining higher Cascade peaks would not interfere.

W7IUV To VK4YB courtesy: Hey What's That Path Profiler

 To VK4YB courtesy: Hey What's That Path Profiler

The path from John, VE7BDQ, already heard in VK, is also easier than from here. Not far from the water, John has a pretty clear shot across Georgia Strait, giving his signal lots of time to gain altitude and clear those pesky Vancouver Island peaks.

VE7BDQ To VK4YB courtesy: Hey What's That Path Profiler

VE7CNF's (Toby) path profile is similar to mine in that he is confronted very early with a hill to clear. Once over that his signal should be well above the mountains.

VE7CNF To VK4YB courtesy: Hey What's That Path Profiler

VA7MM's (Mark) path profile looks a little better than Toby's as there is a little more distance for his signal to gain altitude before passing over Vancouver Island. Mark was also able to detect VK4YB's WSPR signal earlier this spring and is looking forward to the fall tests with Roger.

VA7MM To VK4YB courtesy: Hey What's That Path Profiler

VE7CA's (Markus) path profile is probably the best of all of us on the west coast as he is located high up on the hills to the north of Vancouver along with an open shot to the ocean.

VE7CA To VK4YB courtesy: Hey What's That Path Profiler

I think my only advantage here is my quiet receiving location as it's going to take some brute-force to get over those nearby peaks. Like many of those operating from the suburbs, higher noise levels really take their toll on weak-signal reception and that will be the biggest obstacle for those operators in the city. Twenty years ago, this would not have been nearly such a problem!

VK4YB Path To Pacific courtesy: Hey What's That Path Profiler

Shown above is Roger's path to the Pacific and illustrates one of the reasons why he has the best signal into North America on MF! Although 30 miles from the ocean, there are no obstructions, yet ... coming soon is a 120' cell tower, directly in line with North America and less than 1000' from his antenna. Hopefully it won't cause any problems other than being a dreadful eyesore.

As the solar activity slowly abates (but not this week!), propagation on 630m will slowly get better and better ... hopefully along with increased levels of Canadians transmitting on the band, and lots of stations in the USA. It is hoped that our enthusiastic neighbours to the south aren't too far away from getting the band fairly soon. Better get those soldering irons warmed-up so you are all ready to go!