Posts Tagged ‘JT9’
On Saturday morning, VK4YB and I had our second QSO on 630m using JT9, the WSPR QSO mode. Signals were slightly better than our initial contact but still far from previously seen conditions on the 11,000 + km Trans-Pacific path. However what happened following our contact was equally exciting.
I thanked Roger for the contact, via the ON4KST LF / MF chat page and indicated I was going back to bed as it was still pre-sunrise here on the west coast. He indicated that my signal strength had increased noticeably on my last two transmissions and asked if we might try CW for a few minutes.
We had previously devised our CW protocol to follow a similar one to that used in CW moonbounce work. We would transmit and receive in one minute sequences, with me transmitting on the even minutes and Roger on the odd. Instead of using the RST code for signal reporting, an 'O' is used to indicate reception strong enough to have been able to copy both calls. Both stations are required to copy the 'O', which cannot be sent until both calls have been fully copied. An acknowledgement ('R') must also be sent and copied by both stations to indicate receipt of the signal report. Once the 'R' has been copied, the final transmission(s) are a '73'. Once both stations have copied the 'R', the '73' is technically not required but when copied, further confirms the completion of a valid contact.
For both of us (late at night for him and pre-dawn for me), it was a bit of a mad scramble to make a quick changeover to CW. From my end, there are a number of changes that must be made correctly to avoid over-driving the transverter and damaging the frequency doubler as well as changing to manual PTT to avoid hot-switching of the antenna relays. I also need to bring up the PC's visible clock-face with its sweep second-hand ... but we both made the transition in about two minutes.
We ran for about 45 minutes during which time I heard Roger's CW on two back-to-back sequences (1331Z and 1333Z), copying both calls on each sequence. From 1331Z on, I added Roger's signal report to my calls to him ... 'VK4YB VE7SL OOO'.
We stopped at my sunrise but Roger had only copied fragments of my transmission and never enough to copy both calls. It appeared that we could both have used a few more db on the path as previous estimates have indicated that we might see at least another 5 or 6db yet, on a really good morning. As well, it seemed that the TP pipeline on Saturday morning had centered itself to my south, around northern California and VE7 was on the far northern edge of the propagation path.
Well it seemed that Sunday morning had moved the path further to the north and our 'extra 5-6db' was on hand. All of the local VE7's had numerous decodes of Roger's WSPR signals, including my own 20 decodes in the pre-dawn hours, but ... as 'Murphy' would have it, Roger was suffering receiver-blocking thunderstorm / lightning noise, keeping his K3's s-meter hard against the pin and absolutely no chance of a CW sked. It may have been a much more exciting morning had the spring weather near Roger been more cooperative.
This morning, the weather was still restricting good reception down-under but is forecast to dissipate shortly. But Murphy has not finished with us yet, as the TP path had also noticeably deteriorated today as well. It looks as though the challenge will now be getting everything to come into perfect alignment before the summer weather in VK shuts our CW attempts down for the season.
Shortly before sunrise yesterday morning, VK4YB (Roger) and I were able to work each other on 630m ... 475.300 kHz to be exact!
This is the first-ever QSO between North America and Australia on the relatively new 630m MF band. As well, at 11,802km, it presently represents the furthest two-way contact on this band, worldwide ... but I don't expect this record will last very long once the U.S. gets the band as I believe Roger's fine station is very capable of reaching much further afield.
Our contact on JT9, the WSPR QSO mode, was made at 1319Z, about 30 minutes before my local sunrise with the sky surprisingly bright. Blog readers will know that Roger and I have been carefully watching the pre-dawn Trans-Pacific propagation path for the last week. I have been checking-in with him via the ON4KST LF/MF chat page every morning at around 0345 local time at which point a decision is made ... "get out of bed and head for the shack" or "go back to sleep". Each morning's (or in Roger's case, each evening's) propagation quality is assigned a code number by Roger, based upon what he has been hearing during the early evening hours ... a '6' or below is 'sleep-time', a '7' is a 'you decide' while an '8' or above is 'get your butt moving'.
Yesterday, Roger issued a 'code 7' but as I joked with him later, I think he tricked me as it seemed more like a '6.5' from this end! Trans-Pacific conditions were very good about 500 miles to my south but seemed to drop-off quickly much further to the north. I also need to get over a significant obstruction immediately to the SW of me and in line with Roger. That's me directly at the base of the hill on the right while the remaining peaks are on nearby Saltspring Island and then Vancouver Island before reaching the open Pacific.
I believe this requires some enhancement of high-angle arrival (and departure) which often occurs around dawn due to a short period of ionospheric 'tilting'. This is often noted by topband operators near their local sunrise, who regularly observe stronger signals on low (cloud-warming) dipoles than they do on their normal large (low-angle) verticals or beverage antennas.
We enjoyed significantly stronger conditions a week ago, but unlike Thursday when I could run at full 5W EIRP, I was only able to generate a little less than 1W EIRP at the time. So far, this week, conditions have been improving steadily each day, from a 'code 3' to a 'code 7'. Hopefully they will continue to improve and we can do it all over again sometime soon.
With my new antenna / transverter / amplifier relay control box working nicely, it seems that Roger and I can now fully take advantage of TP propagation from 'mediocre' to 'excellent' but we have yet to see just how good it can get.
|Roger's signal is at +1100Hz|
It is hoped that our contact will inspire new interest among amateurs worldwide and particularly in North America. If you are planning a station, it seems that the main mode of two-way communications will be CW or JT9 ... a simple transverter would allow both modes as well as the use of the WSPR beacon mode. More information may be found here as well as in earlier 630m blogs.
See also: http://www.arrl.org/news/a-record-breaker-on-630-meters
As mentioned in my last blog, using a transverter to drive a separate amplifier requires some method of switching system in order to automatically handle the antenna, transverter and amplifier input / output ports. To run a relay switching system in the WSPR or JT-9 modes requires that the switching be controlled by the transceiver's PTT line which in turn is controlled by the WSPR software. Using VOX keying is out of the question as it causes the relays to be 'hot-switched' and with higher power will eventually lead to their demise.
For many years I managed PTT line control via my laptop's comm port but these are now things of the past, requiring switching to be done via the USB port. There are many commercial products available that will do this nicely as well as handle the audio feed from radio to computer and vice-versa, but I found that my homebrew version worked just fine. Making it work via the USB port however required a serial-to-usb converter. This was described here, in an earlier blog and for the few dollars invested has proven to be a very reliable interface.
The schematic of the switching control unit is shown below. It uses two inexpensive OMRON G2RL-1-E DC12 relays purchased from Digikey. Although not coaxial, the $3.09 (U.S.) relay will easily handle a kilowatt as decribed by W6PQL. These relays have large contacts, rated at 16A. I added a few extra components that absorb any relay switching transients as well as remove any RF on the control lines.
|Relay Control Unit|
|Keying Line Damper: courtesy: KK5DR|
I must say a few words about Digikey's service. I really am amazed at what a superb job they do in supplying hobbyists with small orders. So many companies nowadays cannot be bothered with such things or demand a large minimum order for the privilege of handling your purchase! From what I can tell, Digikey bends over backwards to help out the little guy, with no minimums as well as dirt-cheap, fast shipping. Living in Canada, I'm used to U.S. dealers making me jump hoops to place an order, only to find out that the cost of shipping is often prohibitively high or they ship only via UPS which I will not accept.
I placed a small two-page order with Digikey via their excellent web site on a Tuesday afternoon. On Friday morning, there was a knock at my door at 0800 hours ... it was a courier service delivering my parts! To put this in context, I live on a small island in the middle of Georgia Strait, accessible only by air or by ferry. To me this service is incredible and the cost of postage was only $6.00 (U.S.). I really have no idea how they do this but they obviously have put into operation a very efficient system ... hats off to them and their skilled management that has figured this all out. A few years ago I sent in orders to both Digikey and to Mouser, each within an hour of each other. Like my recent order, the Digikey parts arrived in just a few days while the Mouser parts took over three weeks ... perhaps things have changed since then but this is the reason I use and recommend Digikey whenever I can.
Once I had the needed parts, I quickly built a PCB for the switcher and put it together in a day so that I might begin 630m skeds with VK4YB as soon as possible.
If you would like a full-size layout suitable for the iron-on toner PCB construction method, I'll be happy to send you one via email.
The first test run with VK4YB at 0300 local time proved problematic. When I fired up at full ERP, I immediately saw some output instability on the scopematch screen. Before I could shutdown however, I had blown a FET in the amplifier, shutting me down and sending me back to bed to worry about the situation.
Having had time to think about the problem made me suspect something in the new relay changeover unit since that was the only new variable in the system. I suspected that perhaps the relays were not fully seated before being hit with full RF output and the possible hot-switching had caused enough short-lived SWR to take out the very reactance-sensitive FET final. In many years of operation with the amplifier, this was the first blown FET I have had. When I built it, I made sure that the FETS would be easily accessible (see below) should such an occasion arise ... unlike my initial transmitter, where replacing a FET was a nightmare.
Fortunately, when FETs go south on a push-pull amplifier, only one FET will blow ... whichever one was conducting at the time, thus preserving the remaining FET. I flipped a coin and unsoldered the source lead of the left hand FET and measured it. Sure enough it had a drain-to-source short. My day was off to a better start. Once replaced, I set out to determine what had caused it to blow in the middle of the night.
Since I didn't want to blow another FET, I could only 'key-up' in very short bursts and see if the instability was still present. I put the amplifier on a dummy load and everything seemed normal but when put onto the antenna, it reappeared. Suspecting an arc in the loading coil, I checked it carefully. I indeed did find a charred blackened section near the top high-voltage end of the coil but that could have been a short-lived event from the past as I'm sure small crawly things often meet their demise between the windings without causing any problems other than a quick puff of smoke or a short-lived arc to the PVC coil form.
After cleaning the coil and removing any carbon paths as well as giving it a few coats of varnish, I was hopeful that the problem would be gone ... but no, the scopematch indicated it was still misbehaving. As well, I could hear a weak but audible high-pitched oscillation coming from somewhere in the amplifier's circuitry. I suspected that it came from one of the output transformers but with the fan noise it was impossible to accurately locate the source of the rogue 'squeal' when briefly keying-up.
Fast forward several hours of pulling out what was left of my hair and I was no further ahead. The amp continued to work fine at high power, via the new relay system, into my dummy load but into the perfectly matched antenna, the problem remained. It was at this point that I decided to look at the input signal from the doubler, a nice squarewave at 950kHz for the amp's divide-by-two input chip. The scope instantly indicated a dual squarewave with more than one frequency present!
|Recently built W1VD 'Frequency Doubler'|
It looked like the doubler was not getting enough 475kHz input to actually double properly and its output was a mixture of 950 and (mostly) 475kHz. The amp's divide-by-two input would then try and turn this into a mixture of 475 and (mostly) 237 kHz which the highly-tuned antenna system would balk at, producing the unwanted FET-killing reactance. Being passive and none-reactive, the dummy load was quite happy to take the signal all day long if I let it.
With the mystery solved, full ERP beaconing and scheduling with VK4YB has begun once again, but the TransPacific path has been stingy for the past few mornings ... hopefully this will change now that I'm ready again, barring any further complications.
This past week I was eventually able to mate my W1VD frequency doubler with my 630m FET amplifier and run some higher powered tests on 630m WSPR and JT9 modes.
Up until this time, I have been limited to about 1/2 W EIRP but using the amplifier allows me to get to the 5W EIRP limit. I have been using the VK4YB transverter's 475kHz reduced output of 1W and driving the doubler previously built as part of a transverter project. The doubler produces a nice 950kHz squarewave to drive my amplifier's divide-by-two flip-flop input circuit which in turn produces the dual antiphase outputs needed to drive the push-pull switching FETs in the final amplifier. Being a linear transverter, when used alone at 70W, it will run any mode that the IC756 ProIII will produce such as SSB, WSPR etc, but my switching FET amplifier is class-D, non-linear, which limits it to non-linear modes such as CW, WSPR and JT-9, the most popular modes on 630m.
A few days ago, VK4YB and I ran our first 630m sked on JT9 as conditions looked favorable. Unfortunately, this was before I had my transverter / antenna switching system completed so I was limited to the barefoot transverter at ~ 1/2W EIRP. Using a transverter to drive an external amplifier means the antenna must be switched between the amplifier output and the transverter input in addition to switching the transverter's output between the antenna and the amplifiers input. I'll post details of my switching system, and inexpensive but power-capable relays, in an upcoming blog as there are probably many 630m operators planning on doing something similar.
Thanks to Roger's huge antenna, his 90W signal was making it through well enough on this end but he was not able to decode anything from me.
1109 -26 0.3 1098 @ VE7SL VK4YB QG62
1111 -28 0.3 1098 @ VE7SL VK4YB QG62
1147 -24 0.1 1100 @ VE7SL VK4YB QG62
1149 -27 0.1 1100 @ VE7SL VK4YB QG62
1153 -27 0.1 1100 @ VE7SL VK4YB QG62
1159 -26 0.1 1100 @ VE7SL VK4YB QG62
1209 -26 0.0 1100 @ VE7SL VK4YB QG62
1225 -25 0.1 1100 @ VE7SL VK4YB QG62
1227 -26 -0.0 1100 @ VE7SL VK4YB QG62
1229 -24 0.1 1100 @ VE7SL VK4YB QG62
1239 -23 0.1 1100 @ VE7SL VK4YB QG62
1247 -26 0.0 1100 @ VE7SL VK4YB QG62
1249 -26 0.1 1100 @ VE7SL VK4YB QG62
1253 -23 0.1 1100 @ VE7SL VK4YB QG62
1255 -28 0.1 1100 @ VE7SL VK4YB QG62
1257 -26 0.1 1100 @ VE7SL VK4YB QG62
1303 -27 0.2 1100 @ VE7SL VK4YB QG62
1305 -23 -0.1 1100 @ VE7SL VK4YB QG62
1307 -25 -0.1 1100 @ VE7SL VK4YB QG62
1309 -23 -0.1 1100 @ VE7SL VK4YB QG62
1313 -25 0.0 1100 @ VE7SL VK4YB QG62
1319 -27 0.0 1100 @ VE7SL VK4YB QG62
1323 -22 0.1 1100 @ VE7SL VK4YB QG62
1325 -25 -0.1 1100 @ VE7SL VK4YB QG62
1327 -24 0.0 1100 @ VE7SL VK4YB QG62
1329 -25 0.0 1100 @ VE7SL VK4YB QG62
My location on the 'wrong' side of Mayne Island requires me to fire directly into a very nearby 600' hilltop, directly in Roger's path.
|I'm at the base of the hill on the far right.|
The large mountains are on Vancouver Island and then open Pacfic.
With the antenna / transverter / amplifier switching unit complete, Roger and I will continue to watch band conditions favorable to the Trans-Pacific path and hopefully exchange signals sometime this fall before the path disappears until next spring. For Roger, near Brisbane, the path peaks for him in the late evening while for me, it means crawling out of bed at 0330 local time to check the prop, hoping to find good signals from down under ... working VK on 630m would be well worth losing a few hours of nightly sleep!
As our sunsets start to come earlier and dawn arrives later and later, the sun's accelerated southerly excursion has brought sudden changes to 630m propagation.
This past weekend's CLE activity saw universally poor propagation as well as weather related QRN from lightning ... but as usual at this time of the year, things can change rapidly. Wednesday's overnight map of my own 630m WSPR activity illustrates why September propagation on LF and MF can often be spectacular and this is with just 65 watts total power output:
Among other things, the map indicates the growing interest among U.S. amateurs in the 630m band. Hopefully they won't have to wait too much longer, although I seem to be saying this more often than I would like to. It is of interest to note that even though these were WSPR reports, signal levels at most reporting stations were either into the 'audible CW' levels or at 'JT9 workable' levels ... all stations should be workable once the 630m ham band becomes a reality for all North Americans. Midwinter conditions over the next several years should see an abundance of transcontinental contacts on both CW and on JT9!
The east-west path is the bread and butter direction for interesting possibilities, when it comes to those of us in VE7 land. Normally it only really sets in when geomagnetic conditions are quiet but, as a result of coronal hole streaming, this week's geomagnetic field has been anything but quiet. As John Langridge, KB5NJD / WG2XIQ reported today in his invaluable '630m daily reports':
The geomagnetic field was extremely active, with many reporting periods at storm levels. The Bz is pointing to the South and solar wind velocities are very high, peaking at 700 km/s. This event is significant and I am just glad to see that it is helping and not hurting propagation. When will the bottom drop out? Clearly there is a lot going on here that we do not understand.
With stormy conditions continuing throughout the week, Friday's path to down-under enjoyed some enhancement as well, not unusual when the east-west path is disturbed. VK4YB's 90 watt signal was widely heard by several VE7's (VE7CNF, VA7MM and VE7BDQ) in the predawn hour, as Roger's signal peaked up briefly for several WSPR decodes.
As the coronal hole streaming continues, this morning's path to VK seemed even better along with a new antenna at VK4YB favoring the northwest:
12:24 VK4YB 0.475622 -21 VE7BDQ 11844 km
12:12 VK4YB 0.475621 -22 VE7BDQ 11844 km
12:08 VK4YB 0.475622 -17 VE7BDQ 11844 km
11:04 VK4YB 0.475622 -24 VE7BDQ 11844 km
11:02 VK4YB 0.475623 -22 VE7BDQ 11844 km
10:54 VK4YB 0.475623 -22 VE7BDQ 11844 km
12:28 VK4YB 0.475626 -21 VE7SL 11820 km
12:24 VK4YB 0.475625 -23 VE7SL 11820 km
11:54 VK4YB 0.475623 -25 VE7SL 11820 km
11:04 VK4YB 0.475623 -23 VE7SL 11820 km
11:02 VK4YB 0.475625 -26 VE7SL 11820 km
10:54 VK4YB 0.475626 -21 VE7SL 11820 km
11:22 VK4YB 0.475614 -28 VA7MM 11872 km
11:04 VK4YB 0.475614 -28 VA7MM 11872 km
11:02 VK4YB 0.475615 -33 VA7MM 11872 km
10:54 VK4YB 0.475615 -26 VA7MM 11872 km
I should mention that the other VE7 stations are all operating from noisy suburbs near Vancouver ... clearly fine examples of what can be done on 630m under less than ideal operating conditions and by paying close attention to system optimization. Please don't let living in the city stop you from enjoying the mysteries and challenges that our latest ham band has to offer ... as mentioned earlier, there is still much to be learned about using this band at amateur radio power levels and small backyard antennas. How exciting is that!
As mentioned in previous blogs, this summer's Es season on 50MHz has seen a huge increase in the number of stations using the weak-signal JT65 mode.
Although this mode has been around for a few years, for some reason, it really took off this season. I witnessed many long-time, 'CW-forever' operators (myself included), gingerly move up the band to see what this mode could offer.
At first I thought the activity I was seeing was probably mostly from magic-band regulars, who like me, were also curious ... but I now think this is not the case.
Normally, my 6m summertime Es activities result in just one or two stations requesting a QSL to confirm the contact. These are usually guys that either need a VE7 card or are looking to confirm my grid-square ... just a few cards arrive, in spite of many dozens of contacts over the summer months. This summer I noticed a much different pattern.
This summer saw a tenfold increase in the number of QSL requests and every single one was for a JT65 or JT9 digital mode contact! It soon became apparent that these were not 6m diehards that had just moved up the band, but rather, very enthusiastic newcomers to the band ... what an exciting thing to see! Many of the cards did not have any grid-square information ... the telltale sign of all VHF operators. They had discovered the magicband, using JT65.
Perhaps these were mostly 'no-code' amateurs or those living in antenna-challenged situations such as condos or apartments. Whatever the reason, it really is interesting to see such a profound change in 6m operating tactics, by both the veteran ops and by the newcomers ... all happening so quickly. Hopefully some of the new arrivals will venture down the band to try CW or SSB where contacts can be made much more quickly than on the digital modes but all of this new activity is wonderful to see.
Thursday's blog lamenting this summer's poor domestic Sporadic-E season on 6m must have struck a sour note with the propagation gods as Saturday afternoon and evening saw a massive opening to the eastern U.S., Alaska as well as to the Canadian Arctic ... it was even strong enough to show up the next morning and continue on and off for most of the day. Now that's the type of thing we used to see with fair regularity and it was a welcome respite from what has generally been acknowledged, along with last summer, as the poorest Es seasons in many years. The long-lasting, strong-signal opening provided us dedicated 6m junkies with a nice late season flurry of fun, which would not have been out of place had it occurred in mid-June ... maybe the Es 'metamorphosis' eluded to in my last blog also includes an extension of the normal season. Who knows what effect global warming is having on this aspect of natural phenomenon ... there is just not enough yet known about this fascinating mode of propagation that generates so much interest every summer.
The map below shows the 'leftover' activity on Sunday morning ... not as much as Saturday night but still a pretty good showing for the last day of July!
I spent most of my time working this opening on JT65, up at 50.276, and learning the ropes of this fast-growing mode. One thing is abundantly clear however ... ideally, the chosen JT mode for 6m Es should be JT9 and not JT65.
Using JT9 would allow 10 times the number of stations to fit into the present JT-window ... that's 100 JT9 stations instead of 10! With JT65, the window fills-up quickly and the QRM can soon take its toll with the usual ear-splitting strength of Es signals.The waterfall below shows the much narrower, more sensitive JT9 mode on the right compared with the wider JT65 signal on the left.
I took the opportunity to send out a few JT9 CQ's and did work a number of stations with several of them being well into the -20db range ... too weak for CW but readily worked on JT9. The sensitivity of JT9 will allow two-way contacts to be completed right down to the -27db range, over a one minute transmission period. This is pretty close to the popular WSPR none-QSO mode! I'm surprised that WSPR is so popular on HF when hams could actually be working each other, on-the-air in weak-signal mode JT, instead of relying on a backdoor computer link to see who is hearing their signals ... isn't two-way communication what it's all about? Granted, WSPR beaconing is great for observing propagation trends when you can't be there to watch, and therein lies its utility. Please excuse my short WSJT rant!
Saturday night's opening provided another rare visit from the 6m 'snowman' ... VYØSNO/b, located in Iqaluit, Nunavut in the Canadian Arctic. The beacon is rarely heard as far west as VE7 and it is always a great treat to catch it. It is basically unmaintained so when it fails, may never be repaired ... it's nice to know that its 25 W transmitter is still doing the job. I suspect that if anything fails, it will be the antenna in the brutal Arctic winter weather. The beacon's vertical antenna is located on the top of the high building on the left.
|Sunset at VYØYHK courtesy: https://thesongiliveby.com|
This short video was made during Saturday evening's opening to the north and before the VYØYHK/b appeared. The weaker beacon on 50.030 is VY1DX in Whitehorse, Yukon Territory.
This morning, as I write this, the band is open to W1 and points to the east ... still some life left in the band yet.
It will be interesting to watch what happens over the next two weeks, when most Es activity on 6m usually folds its tent and quietly disappears until the following May ... let's hope the Fat Lady still needs more practice before pulling the curtain.