Posts Tagged ‘MF’
630m – The Path To VK
July 19th, 2016 | 
Author:  |
| 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.
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| VE7SL To VK4YB courtesy: Hey What's That Path Profiler |
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| W7IUV To VK4YB courtesy: Hey What's That Path Profiler |
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| 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.
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| VE7BDQ To VK4YB courtesy: Hey What's That Path Profiler |
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| VE7CNF To VK4YB courtesy: Hey What's That Path Profiler |
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| VA7MM To VK4YB courtesy: Hey What's That Path Profiler |
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| VE7CA To VK4YB courtesy: Hey What's That Path Profiler |
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| VK4YB Path To Pacific courtesy: Hey What's That Path Profiler |
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!
Is Your Miniwhip Too High?
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| The Mini-Whip at University of Twente's (Netherlands) Remote Receiver |
A recent posting to Yahoo's ndblist Group described an interesting experiment by Dirk Claessens regarding the signal-to-noise ratio (SNR) versus height of his PAØRDT active whip. Dirk's tests were posted on Yahoo's Navtex DXing Group where some further interesting discussion seemed to confirm his findings.
Here is what Dirk discovered, backed-up with his graph data, clearly pointing to the 'ideal height' at his location ... and probably yours as well.
Hi all,
You may recall that to get rid of a source of QRM, my whip is now hanging from a rope-and-pulley system, about 5 .5 mtr from the house, at a height of 7 meter agl.
As the height of the whip can easily be changed, this is an ideal situation to test the behaviour of the whip wrt noise levels, optimal height etc..
I had done this test before some 4 years ago, but not very precise. Time to do it again, and documenting it.
What I also wanted to check, is if there were any noise sources of the own house possibly reaching the whip.
(how far does the "noise bubble" go in function of the height?)
The Perseus was tuned to 549 KHz Deutschlandfunk Nordkirchen, the station closest to 518.
2 markers were set, one to the signal, and a reference marker in a quiet spot nearby on 543 KHz, to get a reading for the noise floor.
The whip was then lowered in "1 meter each minute" steps, readings were taken and written to the marker file.
First the absolute values were plotted.
Note that: blue = noise floor, red = signal, and that the left and right axis scales have identical spans of 19dB, but are shifted, in order to get a compact graph.
We see that for a delta height of 6 meters:
-the noise floor goes up ~8dB, or 8/6 = 1.3 dB/m, almost linearly.
-the signal goes up ~14 dB, or 14/6 = 2.3 dB/m, clearly curved and showing a maximum at ~5..7 m.
The continuous lines are polynomic (2nd degree) regression lines.
The noise on the measurement values seems to increase with decreasing height. Was this caused by my body standing under the whip, and near to the whip for the lowest measurements??
What really matters of course, is the signal over noise value, this is plotted below:
-Within a narrow 1 dB band, the curve shows a clear optimum in the region of 4..7 m agl, a familiar value often given as optimal by Roelof.
-The measurement was performed during the day and thus with ground wave propagation. As the whip is truly omnidirectional, I cannot see a reason why the behaviour would be different at low angle DX signals.
- At 5.5 meter from the house, the whip seems to be outside of the "noise bubble"
and later, following discussion:
I have just checked the noise floor again at 518 (with no signal present)
Perseus set to 125 kS/s, Span/RBW 25/30.5
Shield grounded: -125 dBm
Not grounded: -110 dBm
That's a whopping 15 dB difference!
I have also buried the coax ~20cm deep from the grounding point to where it enters the house.
The ideal height was also that recommended by Roelof, PAØRDT, originally and points out that one of antenna-building's most sacred commandments ... "the higher the better", is not always true!
I have often recommended this simple antenna for those looking for a very effective yet low-footprint receiving antenna for use on the LF and MF bands.
Much more information about Roelof's popular miniwhip may be found in previous blog discussions here.
CLE 208 Results
This past weekend saw another of the monthly CLE listening challenges.
'CLE's' are 'Co-ordinated Listening Events', and NDB DXers around the world focus their listening time on one small slice of the NDB spectrum.
If you are interested in building a 630m system, doing some listening on the high end of the NDB band is a great way to evaluate your station's receiving performance.
The frequency range covered for CLE 208 was 400-419.9 KHz where a fair number of North American NDBs' can be found. Beacons at this end of the band also tend to propagate better than those at the lower end near 200KHz.
This weekend, typical summertime conditions prevailed, with extremely high levels of thunderstorm / lightning QRN ... propagation itself was not too bad for the middle of summer.
As usual, I set up my Perseus SDR for hourly two-minute captures of the allocated spectrum and spent a few hours going over the files during the day. I have yet to purchase and download the latest version of Perseus software but I understand that there are several improvements over the system I am using ... which is excellent for my present needs.
Here is my weekend CLE log:
02 10:00 400.0 QQ Comox, BC, CAN
02 06:30 400.0 FN Fort Collins, CO, USA
02 10:00 400.0 CKN Crookston, MN, USA
02 10:00 400.0 1L Fort MacKay, AB, CAN
02 08:30 401.0 YPO Peawanuck, ON, CAN
02 08:30 402.0 M3 Kindersley, SK, CAN
02 08:30 402.0 L4 Nipawin, SK, CAN
02 11:00 403.0 AZC Colorado City, AZ, USA
02 08:00 404.0 MOG Montegue, CA, USA
02 09:30 404.0 GCR Cordova, ALS
04 09:00 404.0 FNB Falls City, NE, USA
02 08:00 405.0 9G Sundre, AB, CAN
02 08:00 405.0 2K Camrose, AB, CAN
02 08:30 406.0 YLJ Meadow Lake, SK, CAN
02 10:30 407.0 ZHU St Hubert (Montreal), QC, CAN
03 10:30 407.0 CHD Chandler, AZ, USA
02 10:30 408.0 JDM Colby, KS, USA
02 08:30 408.0 Z7 Claresholm, AB, CAN
02 08:30 408.0 MW Moses Lake, WA, USA
02 08:30 410.0 GDV Glendive, MT, USA
02 10:30 411.0 ILI Iliamna Apt, ALS
02 09:00 413.0 YHD Dryden, ON, CAN
02 04:00 414.0 YZK Harper Ranch, BC, CAN
02 10:00 414.0 LYI Libby, MT, USA
02 10:30 414.0 IME Sitka, ALS
02 09:00 415.0 LO West Yellowstone, MT, USA
03 09:30 415.0 CBC Cayman Brac, CYM
04 08:30 419.0 RYS Detroit, MI, USA
Final details can be found at the NDB List Website and worldwide results, for every participant, will be posted there a few days after the event. If you are a member of the NDB list Group, results will also be e-mailed and posted there.
The very active Yahoo NDB list Group a great place to learn more about the 'Art of NDB DXing' or to meet other listeners in your region. There is a lot of good information available there and new members are always very welcome.
Hunting For NDB’s In CLE 207
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| 'LU' - 214 kHz Abbotsford, BC |
This coming weekend will see another CLE challenge, this time in the LF band from 275 - 425 kHz. with a bit of a twist.
'CLE's' are 'Co-ordinated Listening Events', and NDB DXers around the world focus their listening time on one small slice of the NDB spectrum but this time around, the challenge has been expanded.
From CLE coordinator Brian Keyte (G3SIA), comes the following reminder:
Hello all,
Our special 'Channels Challenge' listening event is nearly here:
Days: Friday 27 May - Monday 30 May
Times: Start and end at midday, your LOCAL time
Range: 275 kHz (or 325) - 425 kHz (see below)
Target: Try to log ANY ONE NDB in each channel
The main challenge is to try and log ONE NDB on each of the 151
channels in the range from 275 kHz up to 425 kHz inclusive.
The 'channel' means the NDB's NOMINAL (published) frequency
(it may not be quite where you heard the Morse ident).
An NDB on a 'half frequency' would be OK. E.g. 345.5 kHz would
count as OK for channel 345, etc. - show it in your log as 345.5 kHz.
Each NDB must be a 'normal' one - no DGPS, NAVTEX or amateur.
If you hear any UNIDs, please show them in a separate list.
So it means a highest possible target of 151 CLE loggings in all - that
will be VERY difficult to reach, probably impossible away from Europe.
If you don't have much time, or if you want to avoid those tough
frequencies shared with DGPS, you can try a reduced challenge of
325-425 kHz. That would give a possible total of 101 NDBs, still VERY
hard for most of us to achieve.
When we first tried this in CLE170 (end of May 2013) the average number
of channels heard was 83 for Europe listeners, and 41 for Rest of the World.
If you have extra time and want to make the challenge more interesting
you could hunt for NDBs which:
# give you the greatest number of DIFFERENT RADIO COUNTRIES heard.
See our Countries list at http://www.ndblist.info/beacons/countrylist.pdf
(Each State/Province in USA, CAN and AUS is a separate radio country)
# OR give the greatest TOTAL DISTANCE from you to all of the NDBs.
# OR include the greatest number of CHANNELS WITH MIDDAY LOGGINGS
i.e. heard within 2 hours of midday by your local winter clock time.
Send your 'Final' CLE log to the List, if possible as a plain text email
(not in an attachment) with CLE207 at the start of its title.
Please show on EVERY LINE of your log:
# The full date or day no. e.g. '2016-05-27' or '27'
and UTC (the day changes at 00:00 UTC).
# kHz - the beacon's nominal published frequency.
# The Call Ident.
Show those main items FIRST on every line, before other optional details
such as Location, Distance, Offsets, Cycle times, etc.
Always tell us your location and brief details of your receiver, aerial, etc.
I will send the usual 'Any More Logs?' email at about 17:00 UTC on
Tuesday so that you can check that your log has been found OK.
Do make sure that your log has arrived on the List at the very latest
by 08:00 UTC on Wednesday 1 June.
I hope to complete making our combined results on that day.
Good hunting,
Brian
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From: Brian Keyte G3SIA ndbcle'at'gmail.com
Location: Surrey, SE England (CLE co-ordinator)
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TIPS!
Try the channels from 325 kHz first - if you start on the more difficult
lower frequencies it might dim your enthusiasm!
As always, you can find advice about CLEs generally and about this
special one by visiting our CLE page: http://www.ndblist.info/cle.htm
This time you won't need a normal seeklist to help you. However,
from our CLE page you could quickly display details of the NDBs on
a particular channel using REU, RNA or RWW as appropriate to you.
Just enter e.g. 345 - 345.5 in the frequencies boxes and click 'Go'.
(REU shows, for example, that hearing an NDB from England on 287
would be a 'first' since 1990!)
If you wish you could use any one remote receiver (e.g. Twente) for
your loggings stating the location and owner - with their permission
if required. A remote listener may NOT also use another receiver,
whether local or remote, to obtain further loggings for the same CLE.
These listening events serve several purposes. They:
- determine, worldwide, which beacons are actually in service and on-the-air so the online database can be kept up-to-date
- determine, worldwide, which beacons are out-of-service or have gone silent since the last CLE covering this range
- will indicate the state of propagation conditions at the various participant locations
- will give you an indication of how well your LF/MF receiving system is working
- give participants a fun yet challenging activity to keep their listening skills honed
Final details can be found at the NDB List website, and worldwide results, for every participant, will be posted there a few days after the event. If you are a member of the ndblist Group, results will also be e-mailed and posted there.
The very active Yahoo ndblist Group is a great place to learn more about the 'Art of NDB DXing' or to meet other listeners in your region. There is a lot of good information available there and new members are always very welcome.
If you are contemplating getting started on 630m, listening for NDBs is an excellent way to test out your receive capabilities as there are several NDBs located near this part of the spectrum.
You need not be an ndblist member to participate in the CLEs and all reports, no matter how small, are of much value to the organizers. 'First-time' logs are always VERY welcome!
Reports may be sent to the ndblist or e-mailed to either myself or CLE co- ordinator, Brian Keyte (G3SIA), whose address appears above.
Please ... give the CLE a try ... then let us know what NDB's can be heard from your location! Your report can then be added to the worldwide database to help keep it up-to-date.
__._,_.___
IC-7300 LF / MF Receive Performance
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| courtesy: Icom's youtube |
Finbar recently had the opportunity to borrow and test-drive a spanking new Icom IC-7300. Like many of those interested in the LF / MF bands, he was particularly curious about its receiving performance in this part of the spectrum. His present mainstay LF receiver is the Icom R-75, which by any standard, is an excellent performer on the broadcast band and below.
Here are Finbar's anecdotal observations made with a borrowed IC-7300:
" ... my nearest radio amateur friend really surprised
me yesterday by telling me he had bought the new Icom 7300 SDR
transceiver. He offered me a quick loan to try it out. I drove the 9 km
straight away and getting home set it up side by side with my Icom R75.
3 hours later I returned it to it's owner having gained a valuable
chance to test it.
First off, he forgot to give me the instruction manual, but after a
short interval I had it sorted out, having seen the numerous videos, on line.
I disabled the MW attenuation and made sure not to have the Pre-amps
on, otherwise, within the medium wave band, it becomes very messy,
as one would expect.
Basically my R75 produced sharper, more sensitivity in the NDB band,
with some signals on the Icom 7300 being very weak to unreadable,
whereas the Icom R75 gave a much more solid signal, on those very weak
signals.
I did not test the rig on short wave, nor did I transmit or even key
it up, in any mode. I was much more interested in it's apparent receive
capabilities.
I will not be buying an Icom 7300, my Icom R75 is just fine and a
great receiver.
Don't get me wrong, the 7300 is a fine set, but as I see it, it
is the first of this new generation of non PC based SDR sets, and very welcome, at that. However the screen is just too small and crowded. Anyone used to a Perseus screen would be irritated by the sheer volume of screen and sub screen, all of which deserve a proper amount of space.
The subsequent new SDR based transceivers by both Icom and other
set makers, will I expect, contain a larger screen, together with an
ability to feed the video screen into to a PC type monitor, yet
allowing the user to use an SDR type transceiver or receiver without being tied down to a PC.
I look forward to these more comprehensive sets coming on the market.
This is just the beginning of a new phase in receiver and transceiver
SDR technology, integrated in the sets without a lumbering PC having to be
run alongside. This will be a breath of fresh air. Bring it on."
Although I don't believe this is the first non-PC based SDR transceiver, it may be the first 'entry-level' radio of this type. These are one ham's observations made over a short period with one particular unit and your experiences may be much different.
Finbar would be very interested in comments on his observations as well as comments on your own experience with the IC-7300's receiver on the LF bands.
The R-75, although now discontinued, still remains one of the best performing LF receivers, dollar-for-dollar, if you're still looking.
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| Icom R-75 |
As well, from my own experience, I can vouch for the superb receive performance of the Icom 756 PRO III on the LF and MF bands.
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| courtesy: http://www.icomcanada.com |
CLE 206 Results
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| courtesy: http://www.solarham.net/ |
As I usually do, I retuned my inverted - 'L' close to the CLE frequency range and set up my Perseus SDR to make overnight recordings every hour.
I capture two-minute files on the hour and during the best propagation times (usually from midnight to dawn), every half hour as well. The next day I review the files, tuning through the band to see what has been captured overnight. As you might imagine, this can take some time but it allows me to take advantage of any propagation peaks that I might have missed had I been listening in real time for just an hour or two. It also allows me to get a good night's sleep!
Conditions were noisy, on all three nights, with lightning activity over the western states ... but for the most part had cleared up nicely after midnight. The last night (Sunday) saw the best overall propagation, even with a K index of 2. A very nice, but short-lived opening towards the east, brought an additional 18 more catches that had not been heard on the first two evenings, along with some nice NDB signals from Ontario.
23 07:30 198.0 DIW Dixon, NC, USA
23 07:00 200.0 YJ Victoria, BC, CAN
23 07:00 200.0 UAB Anahim Lake, BC, CAN
23 07:00 200.0 5M Sparwood, BC, CAN
23 07:00 201.0 ZWN Winnipeg, MB, CAN
25 09:30 201.0 YKX Kirkland Lake, ON, CAN
25 09:00 201.0 GL La Grande Riviere, QC, CAN
23 10:00 203.0 ZKI Kitimat, BC, CAN
23 10:00 203.0 YBL Campbell River, BC, CAN
25 11:30 203.0 TCY Tracy, CA, USA
25 09:30 203.0 AB Aberdeen, SD, USA
23 10:00 204.0 ZQR Regina, SK, CAN
23 10:00 205.0 COR Corcoran, CA, USA
25 09:00 206.0 XBE Bearskin Lake, ON, CAN
24 12:00 206.0 SOW Show Low, AZ, USA
25 09:00 206.0 IIB Independence, IA, USA
23 10:00 206.0 EF Castlegar, BC, CAN
24 05:00 207.0 YNE Norway House, MB, CAN
23 04:00 207.0 PY Fort Chipewyan, AB, CAN
25 07:30 208.0 YSK Sanikiluaq, NU, CAN
25 10:00 209.0 ITR Burlington, CO, USA
23 07:00 209.0 IB Atikokan, ON, CAN
23 12:00 209.0 CYT Yakataga, ALS
23 06:00 211.0 HDG Gooding, ID, USA
23 06:00 212.0 YGX Gillam, MB, CAN
25 09:00 212.0 MPZ Mount Pleasant, IA, USA
23 12:00 212.0 CGL Juneau, ALS
23 06:00 214.0 LU Abbotsford, BC, CAN
23 10:00 215.0 ZAB Edmonton (Intl Apt), AB, CAN
25 09:00 215.0 AT Watertown, SD, USA
25 08:30 216.0 YFA Fort Albany, ON, CAN
23 07:30 216.0 GRF Fort Lewis, WA, USA
23 07:30 216.0 CLB Wilmington, NC, USA
23 12:00 217.0 EC Enoch, UT, USA
24 07:30 218.0 RL Red Lake, ON, CAN
23 12:00 218.0 PR Prince Rupert, BC, CAN
23 07:00 219.0 ZRS Regina, SK, CAN
23 07:00 221.0 QU Grande Prairie, AB, CAN
23 07:00 221.0 9A Hanna, AB, CAN
23 07:00 222.0 WY Wrigley, NT, CAN
25 09:00 223.0 YYW Armstrong, ON, CAN
23 07:00 223.0 YKA Kamloops, BC, CAN
23 12:00 223.0 AFE Kake Apt, ALS
25 09:00 224.0 MO Moosonee, ON, CAN
23 07:30 224.0 DN Dauphin, MB, CAN
23 07:00 225.0 X5 Vegreville, AB, CAN
23 12:00 225.0 LWG Corvallis, OR, USA
25 09:00 227.0 YAC Cat Lake, ON, CAN
25 11:00 227.0 MHM Minchumina, ALS
23 07:30 227.0 CG Castlegar, BC, CAN
23 07:30 227.0 9X Brooks, AB, CAN
23 12:00 229.0 AKW Klawock, ALS
23 09:30 230.0 YD Smithers, BC, CAN
23 09:30 230.0 VG Vermilion, AB, CAN
23 09:30 230.0 BI Bismarck, ND, USA
25 09:00 233.0 QN Nakina, ON, CAN
23 07:30 233.0 OKS Oshkosh, NE, USA
23 09:00 233.0 BR Brandon, MB, CAN
23 12:00 233.0 ALJ Hinchinbrook Island, ALS
24 07:00 236.0 ZHT Winnipeg IAP, MB, CAN
23 07:00 236.0 YZA Ashcroft, BC, CAN
25 09:30 236.0 JB Whitehorse, YT, CAN
24 07:30 236.0 FOR Forsyth, MT, USA
23 10:00 238.0 MPA Nampa, ID, USA
23 05:00 239.0 OJ High Level, AB, CAN
25 10:30 239.0 BBB Benson, MN, USA
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| courtesy: https://www.google.ca/maps/ |
Hopefully you can jump in for next month's CLE activity. The CLE 206 listening results for all North American listeners and those outside of Europe can be found here.
VK4YB Lights Up West Coast On 630m
The past few weeks have seen many of the VK 630m WSPR stations making it into North America's west coast and points east. VK2DDI, VK2XGJ, VK3ELV and VK4YB have been the signals most often seen. Particularly dominant is the signal from Roger, VK4YB, the northern-most station, located in Moorina, Queensland, near the Pacific Ocean.Roger's signal has been decoded locally by myself as well as VE7BDQ and VA7MM, creating excitement over the more normal nightly spots from the central states.
2016-04-13 11:10 VK4YB 0.475646 -28 QG62ku 5 VA7MM CN89og
2016-04-13 11:20 VK4YB 0.475647 -29 QG62ku 5 VA7MM CN89og
2016-04-13 11:28 VK4YB 0.475647 -28 QG62ku 5 VA7MM CN89og
2016-04-13 11:28 VK4YB 0.475644 -23 QG62ku 5 VE7BDQ CN89la
2016-04-13 11:36 VK4YB 0.475644 -26 QG62ku 5 VE7BDQ CN89la
2016-04-13 11:52 VK4YB 0.475643 -25 QG62ku 5 VE7BDQCN89la
2016-04-13 11:56 VK4YB 0.475643 -28 QG62ku 5 VE7BDQ CN89la
2016-04-07 08:54 VK4YB 0.475643 -25 QG62ku 5 VE7SL CN88iu
2016-04-07 09:36 VK4YB 0.475644 -29 QG62ku 5 VE7SL CN88iu
2016-04-07 10:08 VK4YB 0.475644 -29 QG62ku 5 VE7SL CN88iu
2016-04-07 10:18 VK4YB 0.475644 -29 QG62ku 5 VE7SL CN88iu
2016-04-07 11:04 VK4YB 0.475644 -29 QG62ku 5 VE7SL CN88iu
2016-04-13 11:06 VK4YB 0.475644 -24 QG62ku 5 VE7SL CN88iu
2016-04-13 11:10 VK4YB 0.475644 -23 QG62ku 5 VE7SL CN88iu
2016-04-13 11:20 VK4YB 0.475644 -23 QG62ku 5 VE7SL CN88iu
2016-04-13 11:28 VK4YB 0.475644 -28 QG62ku 5 VE7SL CN88iu
2016-04-13 11:32 VK4YB 0.475644 -25 QG62ku 5 VE7SL CN88iu
2016-04-13 11:52 VK4YB 0.475643 -18 QG62ku 5 VE7SL CN88iu
2016-04-13 11:56 VK4YB 0.475643 -22 QG62ku 5 VE7SL CN88iu
2016-04-13 12:16 VK4YB 0.475643 -27 QG62ku 5 VE7SL CN88iu
2016-04-13 12:28 VK4YB 0.475643 -26 QG62ku 5 VE7SL CN88iu
2016-04-13 12:32 VK4YB 0.475643 -25 QG62ku 5 VE7SL CN88iu
2016-04-13 12:54 VK4YB 0.475644 -24 QG62ku 5 VE7SL CN88iu
2016-04-13 12:58 VK4YB 0.475643 -24 QG62ku 5 VE7SL CN88iu
2016-04-13 13:10 VK4YB 0.475643 -25 QG62ku 5 VE7SL CN88iu
2016-04-13 13:24 VK4YB 0.475643 -27 QG62ku 5 VE7SL CN88iu
2016-04-13 13:28 VK4YB 0.475643 -27 QG62ku 5 VE7SL CN88iu
Roger has sent the following information to me regarding his well-planned system:
My antenna is serendipitous.
I am a complete novice on 630m. I only came on the band about 2 months ago at the request of a local friend, Peter, VK4QC. That is not quite true, because I was on the band once before, about a year ago and made one contact and then managed to burn out the front end of my Drake TR7, which I had roughly converted to 630m operation.
My QTH is atop of a stony ridge on 10 acres. The previous owner said there was some soil somewhere, but I haven't found it yet! Ground conductivity is very poor, I think. If you drive in two stakes about six inches apart, an ohmmeter says infinity. That's if you can drive in a stake. Because after the first quarter inch you hit shale rock. Interestingly the shale layers are at about 60 degrees to the horizontal. There are some quartz inclusions. Yes, I have tried crushing the quartz and panning it - no gold!
Getting back to my story, I needed to put up a 630m antenna in a hurry. The idea of winding a big loading coil with the rotatable inner coil was a bit daunting. And putting down ground radials or an earth mat was out of the question. So, using only some wire, string and a bow and arrow, this is what I came up with:
What is missing from that drawing is that the wire is running North-East to South-West, all in a straight line, with the shack at the North-East end. It is line-of-sight from the top of the vertical section to the Pacific ocean. I didn't put the direction on the original drawing because I didn't think it was important. I thought it was essentially a top-fed vertical and would therefore be omni-directional. Nothing could be further from the truth. Experience has shown that it is very directional. I have never had a single report from Japan, and yet my signal has peaked at -3 in Hawaii (about the same distance). Also VK3ELV, using a quarter wave near vertical, gets almost nightly reports from both Japan and Hawaii and at similar strengths. That would seem to indicate a front to side ratio of more than 20dB for my antenna, which is surely impossible?
I estimate the feed point impedance is about 3000 ohms. The ATU has 48 turns on the secondary, tuned by fixed capacitors of 960 pF in parallel with a 500 pF variable which is about two thirds meshed. The primary is 5 turns fed by the transverter having a 50 ohm nominal output. The impedance at the top of the secondary should be near 5000 ohms, but the antenna feed wire is tapped about two thirds of the way up the secondary coil, which gives 1.03 : 1 SWR. The earthy end of the coil is connected to the mains earth and the metal work of the shed. I haven't tried terminating the far end. I did think about connecting it to the fence wire that runs round the property but I thought that might be a bit dangerous. There would be high voltage points in places. The transverter output is nominally 50 watts, but it is giving about 90 watts in reality.
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| Roger - VK4YB |
Like many on 630m, Roger is using an Elecraft K3 into a transverter to generate his 630m 90 watt signal. It is interesting to see the strength of Roger's signal here throughout the night but particularly during the 1152-1156Z time slot. His signal peaked at -18db, right at the level of audibility ... CW levels, but quickly dropped. Throughout the night however, his signal was easily within range of the capabilities of the two-way JT-9 WSPR QSO mode ... had either of us been seriously involved in a two-way JT-9 QSO attempt during that night, it would have been quick work I think.
John, VE7BDQ, has already managed to push his WSPR signal to VK on more than one occasion ... this from a typical, suburban backyard inverted-L. The possibilities are exciting, but will mean some middle-of-the-night vigilance!
As activity on 630m increases in both VK and VE, we are beginning to see more and more DX possibilities arising, particularly during the Spring and Fall equinox periods when this path seems to peak. As activity in Japan picks up, it is only a matter of time before some of them begin showing up in numbers here on the west coast, as the path to JA has always been reliable and somewhat less demanding than the path to down under. I suspect also, that as the present solar cycle draws down (and supposedly goes 'quiet'), 630m Trans-Pacific signals will grow even stronger,and on most other paths as well.
In view of the JT9 QSO possibilities, I think it is clear that I now need to seriously think about building a transverter, allowing me to at least be in 'ready-mode' for the coming 630m challenges ... hopefully for the next equinox.
