Thursday, March 15, 2018

DXers Unlimited, March 13, 2018

Radio Havana Cuba

Dxers Unlimited's middle of the week program for Tuesday 13 March 2018 By Arnie Coro radio amateur CO2KK

Hola amigos radioaficionados... hi my radio hobby friends all around the world... YES, it is time, right for you to enjoy  about ten minutes of all radio hobby related information coming to you from Havana, Cuba. I am your host, Arnaldo, Arnie , Coro and here is item one of today's

High frequency HF bands propagation will show a slight improvement only if solar activity increases during the next several days .... at this moment no new sunspot active region in sight , and the low solar flux is hovering at rock bottom levels around 70 units and even less..

By the way let me tell you that the sudden upsurge in the daily sunspot count and solar flux levels  is something that may happen at anytime during the bottom of the solar cycle ...

Yes,  This is typical of the tail end of a solar cycle, nothing abnormal at all... but it is certainly quite disgusting, due to the long prevailing minimum solar activity  to tune around the short wave spectrum and hear nothing or just very weak signals !!!

According to the most recent forecasts, next year, 2019 is going to be worse  with extended periods of much lower solar activity, that may combine with solar events that will further disrupt propagation conditions. 

Now, as we move into the  spring equinox here in the Northern Hemisphere and autumn equinox below the Equator,the beginning of summer, the propagation conditions on the HF bands from 10 to 20 megaHertz will  improve as soon as more energy reaches the ionosphere from the Sun. 

For those of us that live North of the Equator, one of the most interesting effects of late spring and summer propagation is a consequence of the daytime expansion of  the ionosphere... that causes an increase at night  of the maximum usable frequency for any given path after local sunset...

At times during solar minimum years, during the winter season  the maximum usable frequency at night may drop even below the six megaHertz band amigos !!!

 Now here is item two at the middle of the week edition of Dxers

Unlimited: I continue to enjoy very much the use of the very original software application that runs on practically any computer and  makes possible to see the results of the REVERSE BEACON NETWORK...this is certainly  an amazing achievement accomplished by volunteer amateur radio operators from many countries around the world. 

I would not attempt to describe here how the receiving stations that are known as quote skimmers unquote, automatically pick up amateur CW Morse radiotelegraphy signals that are calling CQ, and then also by means of an automated subroutine measure the CW transmission speed and the signal to noise ratio...

If it sounds to you as science fiction, but it is certainly not, and the now very reliable Reverse Beacon Network is adding yet another tool to learn more about the extremely complex phenomena that make possible ionospheric short wave propagation...

Yes amigos , I continue to run my QRP very low power amateur radio station within the power range of one to five watts, with my favorite setting at the three watts level. On Sunday's afternoons I spend some of my leisure time operating on CW , on , twenty and my CQ calls at speeds between 13 and 16 words per minute and see how my signals are picked up by several skimmers and posted at the Reverse Beacon Network site so that they could be seen by just typing CO2KK, the call sign of my amateur radio station...

Again, I want to repeat this valuable information for those of you interested in knowing more about short wave propagation You may want to visit the home page of the Reverse Beacon Network after calling CQ on CW if you already are an amateur radio station operator, and just learn , for example, what is happening when your friend Arnie Coro called CQ on the ham bands the last time he was on the air.... Just type the following URL on your Internet browser search line:



Then when the site opens and asks for whom you are looking for, type co2kk and you will see the latest spots on each of the ham bands where I called CQ...

Here is now ASK ARNIE, la numero uno, the most popular section of the show... answering today a question sent by listeners from the United States, Canada, Mexico, India, and South Africa, ... they all wanted to know what is the most economical type of antenna that can be used to optimize long distance amateur radio communications on the HF bands.......

That is a really challenging question amigos... but I will try to provide you with information about one of my favorite low cost DX capable antennas for the 20, 17, 15, 12 and 10 meter bands... It is not a multi-band antenna, it must be made for the specific band you want to operate... Results achieved with it are really good, if you are able to install the antenna in the clear...

It is made using locally available and low cost materials... The one third of a wavelength vertical antenna , using four quarter wave elevated radials produces a low take off angle vertical radiation pattern, and is a perfect match for 50 ohms coaxial cables feed line...

I used the 20 meters band version for many years, and my signal was many times as good or even better as the signal delivered by a local amateur operator that used a three elements multi band YAGI... Not to say that he was very upset when we compared signals with a distant station...

He even made a surprise visit to my home because he thought I had installed a three element YAGI ... I took my friend to the rooftop ands showed him the very simple vertical and the elevated ground radials. Then we went down to the station and measured the standing wave ratio , that indicated a 1 point one to one ratio...

That is of course an almost perfect match !!! I had to explain to him that there was no secret linear amplifier feeding the antenna,so what was actually happening was that the 120 electrical degrees height of the vertical monopole was concentrating the signal at low take off angles...

Needless to say that two weeks later he had improved his station by raising the Tribander YAGI to about 15 meters above his roof, and had also installed a perfect copy of my 20 meters band one third of a wavelength high 20 meters antenna. Now more valuable radio hobby related information to keep in mind when you decide to go on the air...

 AGAIN, BE ASSURED THAT I AM A FULL TIME ADVOCATE OF QRP or low power amateur radio operation although it is  quite a challenge, and that is why so many ham radio operators around the world are becoming more and more involved in building or buying CW rigs that are within the power range from 1 Watt all the way up to 5 Watt.... and some of us have installed calibrated signal attenuators that can turn a one watt rig into a one hundred milli watt transmitter at the flip of a switch that places a 50 ohms 10 decibels  attenuator between the rig and the antenna , cutting the power output to just one hundred milli watts...

The most popular CW operating frequencies for QRP or very low power amateur stations are 7030 and 7040 on the 40 meters band, 10 dot 106 on the 30 meters band14060 on 20 meters, 21060 0n 15 meters and 28060 on the 10 meters band....

 Calling CQ on those frequencies will, in many instances, bring back stations that regularly monitor them for QRP signals. You can always go and check if any of the skimmers at the Reverse Beacon Network is picking up your CQ call And by the way before I forget... QRP transmitters running no more than

5 Watts into a half wave dipole fed with coaxial cable by means of a one to one balun and installed at a good height will provide really amazing results.

Send your signal reports and comments to inforhc at enet dot cu or via Air Mail to Arnie Coro, Radio Havana Cuba, Havana Cuba
(Arnei Coro/R Havana Cuba)