DX RXThe Doctor of DX prescribes the |  |
DX RXThe Doctor of DX prescribes the | |
Several weeks ago I was listening to some hams on a net which meets daily on 20M SSB. One fellow (Florida QTH) was complaining to the other that band conditions were terrible. The other (North Carolina QTH) agreed wholeheartedly, lamenting the fact that their daily QSOs were something less than ideal. Not once during the course of the conversation did either gent mention anything about having checked the National Bureau of Standards Station, WWV, for propagation forecasts, copying the daily bulletins from W1AW, or picking up the latest issue of QST and reading the propagation predictions to ascertain the reason for the poor propagation. All these two fellows knew was that conditions were “terrible”. Any serious DX’er would have been able to tell them that “propagation” was poor for them because, on that particular day, a) the solar flux index was very low, b) the ‘A’ index was 26, the ‘K’ index was 3 and rising, and, given the band, time of day, time of year, and physical separation of the two conversationalists, they were on the wrong band!! They would have had “armchair” copy had they been on 75 Meters or 40 Meters that particular morning.
From a Physics perspective, propagation is defined as “to move through a medium”, such as a radio wave moving through the “medium” of the atmosphere. In its simplest form, radio wave propagation is divided into three areas: 1) Ground Wave, 2) Space Wave, and 3) Sky Wave. Ground Wave propagation is vitally important at Very Low (VLF), Low (LF) and Medium (MF) frequencies. In the HF spectrum (3-30 MHz) Sky Wave propagation plays the most important role, and at VHF/UHF and microwave frequencies Space Wave propagation is key. However, as in anything, there are exceptions to all the rules. The manner in which these varying aspects of radio wave propagation behave, is, in large measure, dependent upon time; time of day, time of year, and time of sunspot cycle. If this last statement were, in the strictest sense, 100% true, then forecasting band conditions between any two points on the face of the earth would be a “piece of cake”. But it’s not nice to fool with Mother Nature. She enjoys throwing curve balls at us. As you know, since the sun controls propagation of RF energy, at least within the confines of Mother Earth, it behooves us to pay close attention to “Old Sol”. While we can speak in general terms about the conditions noted above, it is almost impossible to predict, at any given moment, the sun’s surface activity, which is the engine of the propagation phenomenon. While avid HF DX’ers pray for sunspots, avid low band DX’ers (40 Meters and below) relish the “quiet” times of the sunspot cycle, and VHF/UHF enthusiasts love to see flares, aurora activity and other astronomical activities which aid them in their pursuits. Daily measurements of the Solar Flux Index, the ‘A’ Index and the ‘K’ Index provide the ham with a ready tool to determine the probability of successfully communicating on any given band at any given time period.
The sunspot cycle is, on average, a period of about 11 years. The number of sunspots on the surface of the sun are, in general, related to the period of time within the cycle. If the number of sunspots were plotted along an 11-year timeline, a rough sine wave curve is created. At the beginning of each cycle, surface activity is generally low, the number of sunspots is minimal, and Low Band Dx’ing is the norm, with 20 Meters usually being about the highest band useable on a daily basis. Again, this does not always hold. During this past year, there continues to be considerable activity on 17 Meters. Four or five years into the cycle, the average number of sunspots on a daily basis peaks and communications on 15, 12, and 10 Meters is pipeline all over the world. As the cycle passes the peak and the number of sunspots (or the solar flux index) decreases, a gradual decrease in activity is noted on 10 Meters, followed by 12 and 15 Meters. This cycle of activity on the HF bands then repeats itself again.
The number of books written about the subject and science of RF propagation would fill a room (and then some, I suspect). John Devoldere (ON4UN) provides an excellent treatise on the subject of Low- Band propagation in his book “Low-Band DX’ing”. The ARRL Antenna Book provides an excellent introductory tutorial on the subject of RF propagation in general. This is “must” reading if your interests include DX or any other serious HF work. Other subjects include “Gray Line” propagation, Aurora work, Sporadic-E and the like. Additionally, WWV and WWVH transmit propagation data at 18 and 45 minutes after the hour, respectively. This data, together with other information which you provide, can be plugged into various Propagation software, now readily available, and the software will provide you with tables of information about present and projected conditions. Each month QST Magazine publishes charts of propagation predictions in the “How’s DX” column for a one month period. W1AW also broadcasts update bulletins, and the NE1V-5 PBBS retains these bulletins for several iterations. The DX Cluster packet network also provides access to these bulletins, as well as up-to-the-minute transmissions of solar data. These and other resources will be discussed in next month’s column in greater detail.
The subject of good operating practice has been cannon fodder for Amateur Radio writers and public speakers for years. All of us know, or should know, the common courtesies and practices which differentiate a real “pro” from the “LID”. However, each and every one of us, especially in the “heat of battle”, sometimes slip and say or do something which we know is not exactly on the up and up. Or we may just get careless. This morning (8 May) I did just that.....I got careless and QRM’d a DXpedition, unintentional as it was. Believe me, I got a lot of “LID” and other indescribable words (this is a family journal) thrown at me in high speed CW lingo. I have no excuse to offer and I feel like the fellow who discovers that his fly is down while at a church social. It may be instructive to review a few of the more common practices and courtesies. These apply to all of us, not just DX’ers or contesters.
1) Always listen carefully before ever transmitting. If you have one, load your transmitter/amp on a dummy load.
2) When working rapid-fire DX and DX’peditions, first take the time to ascertain if the station is running split mode or simplex. Make sure you can hear the operator well enough to exchange reports before opening your yap. Make sure your VFOs are correctly set for split or simplex operation. This was the source of my error this morning. In my hurry to work ZL8RI on Kermedec Island on 20 CW, I failed to push the little button which would have put me in split mode. I was transmitting on his transmit frequency. I got “flamed” big time.
3) Be patient. Observe how the operator wants the QSO exchange and ensure you use that method.
4) Be considerate. If you have already worked a rare one and a zillion guys and gals are calling, don’t be an “oinker” and hog the time of the DX. Let the others who really need the QSO have a crack. Wait till later to ragchew. Insurance QSO’s usually are very severely frowned upon.
5) Be quiet. Don’t be a “Kilocycle KOP”. If someone QRZ’s the frequency, a simple “Yes” will suffice. Better yet, since you will be joined by 10 x 10 to the 13th power other hams screaming “Yes”, let them do it.
6) QSL promptly. If you have worked a rare one, please consider sending a “green stamp” to cover the expense of return postage. An SAE also helps. If the DX station has a stateside QSL manager, send an SASE. A green stamp doesn’t hurt either, especially at the cost of printing QSL cards today. (Ed Note: A “green stamp” refers to a US one dollar bill. These are accepted almost anywhere. Check first to make sure that the country you are mailing to allows foreign currency)
7) LISTEN...LISTEN...LISTEN. Learn what goes on each day. Learn what conditions to expect. Do not sit on a DX frequency and scream “QSL Info?”. There are resources for that. Do not pound out “di-di-dah-dah-di-dit” when you don’t know who the station is or can’t hear him. If you can’t hear him, you can’t work him. If you LISTEN and can hear him, he’ll ID. Use the resources of the DX Cluster to find, work and QSL the stations you need.
8) Keep a set of notes on daily operations, conditions, stations heard and times, etc. It becomes a valuable resource later.
9) Retain a sense of humor and perspective. Remember, nothing is worth getting so angry over that you have a heart attack. Also remember that Amateur Radio is a hobby and amateur activities should be balanced with your other activities. (This secret helps keep XYL’s happy, OM).
10) Encourage new and young hams and lend them an “Elmer” hand. Show them, by example and instruction, what the hobby is really about. Nothing can be more damaging to a new operator than to be “flamed” the first time out of the gate.
VK/ZL L/P 20M/Late afternoon
Far East/Pacific 40 Meters early AM
Far East 20M mid-mornings
OH0 80/40/30 CW & RTTY
CN8 Late Afternoon 20/17 Meters
Next month we’ll discuss some of the various resources and tools available to the DX’er and Contester.
di-di-di-dah-di-dah.