Dxers Unlimited middle of the week edition for Tuesday 15 November 2016
By Arnie Coro
radio amateur CO2KK
Hola amigos radioaficionados all around the world now listening to the middle of the week edition of Dxers Unlimited, our station's twice weekly radio hobby program. I am your host Arnie Coro,radio amateur CO2KK and here is now our number one topic for today... How you can make yourself a small but efficient vertical antenna for your amateur radio station... It is just 12 foot tall... that is a little more than three and half meters... My multiband small vertical does require the use of at least 4 ground radials... and if installed on top of a mast, if will benefit a lot from the use of elevated sloping radials.
It works nicely on the 15, 12 and 10 meters band without needing a loading coil or capacity hat. As a matter of fact on those three amateur bands the antenna is fed with 50 ohms coaxial cable that ends up into my classic PI network antenna tuner and standing wave ratio meter ... My demonstration to visitors of CO2KK and CL2ROX, our home amateur radio station is to set up Arnie Coro's KK5 portable vertical at our beautiful sun deck... This takes just a few minutes, and when fed into a multi
band HF transceiver... it is very easy to tune up on 15, 12 and 10 meters after laying the 4 radials on the ceramic tiles roofing ... Next step is to show how to use the antenna on the queen of Dxing band... 20 meters... and it only requires to disconnect the center conductor of the coaxial cable, and add a simple loading coil that has several taps... so the antenna can be tuned to the 20, 30 and 40 meters bands...
The aluminum tubing used for the antenna is split into three parts to make it really portable... but for a permanent installation I will suggest using just two sections... a larger diameter base section using
25 millimeters or 1 inch diameter tubing and the upper section using 19 millimeters of three quarters of an inch tubing... The antenna designed for a permanent installation is very rugged and proved to pass the 2005 Wilma hurricane test winds without any problems.
Building the portable version I found out that it was possible to use a car antenna stainless steel whip, that is attached to the main one and a half meter high base section using butterfly nuts, so it is very easy to assemble and take apart. The loading coil consists of a length of 2 inches or 50 millimeters diameter PVC water pipe that supports the winding of 20 turns of number 14 PVC insulated wire to which taps every 5 turns are carefully made... I use a standard cable clamp to connect the antenna loading coil to the right place where resonance is achieved on the 20, 30 and 40 meter bands, easily found with the help of the friendly grid dip meter.. Good connections between the shield of the coaxial cable and the ground radials is a must !!!
The KK5 short vertical seems to put my QRP 5 WATTS station very well on the air on the 10,12,15 and 20 meter bands... and although it works on 30 and 40 meters testing against half wave dipoles for those two bands show that the KK5 is about minus 3 to minus 6 dB when compared with the above mentioned horizontal half wave dipoles...Total cost of the project will not break your bank account, and the antenna can be stored into a canvas back together with the RG58 coaxial cable, the set of radials and the loading coil... I took the prototype to the beach and results on the 20 meters band confirmed that although the antenna is shorter than a quarter wave vertical, it did brought in many contacts especially during the late afternoon and early evening when the best band openings were
happening...
More about low cost antennas for you ham radio station in future editions of Dxers Unlimited.... Now standby for a few seconds ... a station ID will follow. I am Arnie Coro, radio amateur CO2KK in sunny La Habana . Cuba
This is Radio Havana Cuba, the name of the show is Dxers Unlimited and our e'mail address for signal reports, comments and radio hobby related questions is inforhc at enet dot cu, again inforhc at enet.dot cu.. Now here is item two of today's show...Northern hemisphere winter season propagation is now in full swing... but something unusual is happening... I am monitoring more frequent sporadic E layer events than what is considered to be normal during the first half of November...
Maybe we will see a more active sporadic E winter season starting in around a month from now.... Sporadic E layer propagation is capable of generating band openings on the 12, 10 and 6 meter bands, plus very interesting short skip openings on 20 and 17 meters.. I will be monitoring the six meters band SSB voice calling frequencies of 50.110 and 50.125 using a short version of the TTFD antenna that works from 25 to 100 megaHertz... It can also be connected to a scanner that makes possible to explore the segment known as low band VHF, between 30 and 50 megaHertz...
Now item three: ASK ARNIE, la numero uno, the most popular section of Dxers Unlimited is now on the air ... answering a question sent by listener Mark from Vancouver, Canada... Mark wants to know more about kits of parts that are presently available to assemble amateur radio single band transceivers. Well amigo Mark, I am happy to report that there are several QRP rigs kits that are within the power range of 1 to 10 watts... The really wonderful thing about well designed kits is that
they come with all the parts, and with normally well written step by step instructions and also with fault finding information...You do need amigo Mark to be able to identify all electronic components, have a good eyesight , know how to properly solder parts and own a minimum set of measuring instruments, plus a high quality soldering iron... Attempting to assemble a ham band transceiver for the frequency range from 160 to 10 meters if attempted for the first time will require the help of a
more experienced radio amateur that has already succesfully assembled the same kit you are trying to assemble... I do not recommend trying to build your own single band HF transceiver from scratch, as you may end up stuck into problems like not finding specific parts, and that is one every important fact about well done kits.... they do come will all parts properly identified , show how to wind coils or toroids if required, will tell you how to check your progress and above all the really good kits will come with very well written in plain language step by step instructions, and also with vitally important debugging procedures...
Some suppliers of QRP transceiver kits will even provide for expert advice for troubleshooting your radio in case something goes wrong...
Now our next radio hobby related item... an item not frequently heard here in my show.. Si amigos, yes my friends I very rarely provide frequencies of stations and times to listen for one very solid
reason.... WHAT you are able to pick up at your location maybe quite different from what I can listen to here at my Havana, Cuba location...you can try to follow my advice about how to find out new and
possibly rare DX stations on the AM medium wave broadcast band by following this steps... number one keep a daily record of the geomagnetic planetary disturbance indicator ... be especially aware when the A index moves above 10 units... Also if you can find out a reliable source that will show the D layer absorption index, this is an excellent indicator to follow , because lower values will really help to boost the AM medium wave band and the two lower Tropical Bands signals.
To explain it better lower ionospheric absorption from 500 kiloHertz to around three thousand three hundred kiloHertz will certainly increase your chances of picking up the weaker AM broadcast band and the 120 and 90 meters Tropical Band. The lower figure is also a good help to 160 meters band amateur signals !!!
Be aware that any geomagnetic disturbance in progress will require your immediate attention, especially starting just before sunset....
Now at the end of the show a short form propagation update ... solar activity continues to be at very low with the 10 dot seven centimeters wavelength solar flux hovering around 75 units ... See you all at weekend edition of Dxers Unlimited, next Sunday and Monday UTC days just after the top of the hour news here at Radio Havana Cuba
(Arnie Coro)
