Watch Radio Modulation Depth for best Signal Clarity

Set Radio modulation Depth for optimum Clarity For the sake of optimum clarity and intelligibility of radio transmission, the radio modulation depth must be controlled by ensuring that the microphone input level is maintained well within the automatic Level control (ALC) correction range of the modulator. Failure to do so would result in the introduction of audio distortion. Overdriving the modulator will invariably result in the creation of unwanted AF harmonics and spurious products. Consequently, the intelligibility of the demodulated audio on the receiver at the DX end will also suffer proportionately. Several ill-effects of overmodulation will begin to surface. In extreme cases, the overmodulating radio station will begin to splatter across the band. However, with the modern radio transmitters, sideband splatter is usually not the problem. Nonetheless, this could have been a huge problem in earlier transceivers because it would have produced spurious RF components across a significant portion of the band. At times the splatter could have extended across the entire band. This kind of slatter from just one operator might have rendered the band more-or-less useless for... Click Here to Read Full Article […]

Low SSN – Why do most Hams find HF Radio so difficult?

HF Radio communication so difficulties during Low SSN It is true that most ham radio operators around the world in their quest for DX on HF radio find it exceedingly difficult during low SSN conditions at Solat Cycle minimas. Currently, as I write, we are negotiating low SSN conditions as we are making a transition from Solar Cycle #24 to #25. I agree that the difficulties are much greater during this phase in comparison to the high SSN phase. However, the question that is often asked is, are the HF bands practically dead? … The short answer is NO! Can we still continue to make adequate radiotelephony SSB and CW DX contacts on HF during low SSN? YES! … Do we need to fall back on ultra-weak signal modulation modes like FT8 to survive? … NO! … Those of us who give up on SSB phone or CW and find ourselves limited to FT8 are certainly doing something horrendously wrong. Most probably, the ham radio station setup is unsatisfactory… Hold on! I hear some readers saying, what nonsense are you... Click Here to Read Full Article […]

SSN, SFI, Solar Data for HF Propagation

SSN, SFI, Solar Data for HF Radio Propagation Here are some of the important Solar activity parametric data that are responsible for influencing the behavior of the Ionosphere on earth. These, in turn, are instrumental in determining HF radio propagation conditions on various bands. The information presented here is automatically updated on a regular basis. The data-set is presented in two formats below. They are the graph format and a tabular metrics format. The graph which displays the history of measured SSN and SFI derived SSN – SSNf(10.7) that prevailed over the last 60 days is updated once a day, while the Solar terrestrial data metrics table is updated on an hourly basis. This page also explains each and every Solar Data Parameter that we have covered here so that amateur radio operators irrespective of their technical understanding could get a reasonable insight into how HF radio propagation on Earth is influenced by the Sun’s activity. This way, one can watch for changes in various critical parameters and make an informed decision related to HF radio band opening prospects. Why... Click Here to Read Full Article […]

EMI-RFI and Noise related HF Radio Station performance loss

EMI-RFI and Noise related HF Radio Station performance loss HF radio performance loss due to EMI-RFI and noise in and around the station environment is often a major issue that could almost cripple the communication capability. This is especially true during conditions of low SSN, the way it prevails during the ebbing part of the Solar Cycle. Many amateur radio operators do not realize the real consequences and the utter magnitude of loss in their radio station’s performance. More often than not, we have heard statements like – The HF bands are now dead at low SSN, the only viable way is to work HF using FT8, SSB radiotelephony is hardly possible during low SSN conditions, I think I need to invest in a linear HF power amplifier, etc, etc… – We have heard all this far too often. However, it is not necessarily the whole truth. We all agree that during low SSN conditions, negotiating the HF radio bands become more difficult and stringent in comparison to what happens during the better part of the Solar Cycle. When the... Click Here to Read Full Article […]

Inverted V Antenna – A popular Dipole variant

The Center-fed Half-Wave Dipole Inverted V Antenna An Inverted V antenna is a very popular variant of the standard horizontal dipole. In his article, I will try to bust some of the myths associated with Inverted V and dipoles. Just as a regular dipole may or may not always be of resonant 1/2λ length, an Inverted V too may not always be cut to resonance. However, the non-resonant variety is relatively less common, therefore in this article, I will stick to the 1/2λ resonant Inverted V antenna and leave the discussion on the non-resonant variety to another article. Many people might tend to consider an Inverted V as an antenna of a separate genre with its own unique performance characteristics, but it is not. It is essentially another dipole antenna that is physically oriented in a slightly different manner than a regular one. The performance characteristics of an Inverted V antenna is not too different from a horizontal dipole. Therefore, I will not repeat what we have already discussed in the article titled The Ubiquitous Dipole Antenna. Readers are requested... Click Here to Read Full Article […]

Cubical Quads & Delta Loops

Cubical Quad antennas and Delta Loops When we think of a Cubical Quad or a Delta Loop, the picture that we usually visualize is a large multi-element structure of vertically oriented wire loops on boom and mast with a rotator that swings the structure around. They feature a unidirectional radiation pattern with fine overall characteristics and performance. This is very true for cubical Quad and Delta Loop arrays but all Cubical Quads need not be arrays. We can very well have a single element Quad loop with bidirectional radiation properties. In this article, we will examine the Cubical Quad or Delta Loop geometric structure as antennas. The common term Cubical Quad will be used in general for both type of loop structures. However, specific references to Delta Loop will only be made when it warrants a distinction on account of a unique characteristic or feature. Cubical Quad and Delta Loop Geometry Let us start by examining a single Quad Loop and see how it behaves and what it has to offer, In contrast to a dipole which is 1/2λ in... Click Here to Read Full Article […]

Learn CW Morse Code – Get Started

Learn CW Morse Code – Get Started If you are reading this article, then in all probability you either wish to learn CW Morse Code from the scratch or are one of those who learned it earlier in life but still find it an uphill task to copy CW by the ear. Whichever might be the case, do not fret. We will guide you through the process of mastering CW Morse code with a set of scientifically designed lessons in this section of the website. The method that we employ is proven to help learn CW as if it were another language and not a code. This is the crux of the matter. People often make the blunder of memorizing the CW code set consisting of dits-n-dahs. Never ever do that… Those who are absolutely new to CW will be beginning from the scratch. Hence, they do not carry any baggage of bad learning practices. The others who might feel uncomfortable copying CW by the ear beyond a limited transmission speed because they perhaps learned it the wrong way will... Click Here to Read Full Article […]

Global HF Radio Propagation Openings – The Summer of 20

HF Radio Propagation Outlook – The Summer of 2020 In the Summer of 2020, the HF Radio Propagation openings are not so frequent as one would expect under normal circumstances. The reason, as we all know is on account of the phase of the 11-Year Sunspot Cycle that we are going through at this time. The 24th Solar Cycle has ended while the 25th cycle has yet to pick up steam. We are placed at the cusp, which appears like a deep broad valley when observed on a graph. As a consequence, the prevailing SSN is either extremely low or zero (0) most of the days. The 10.7cm Solar Flux Index (SFI) is also near the rock bottom. The solar magnetic activity, as well as the energy and particle ejections, are rather placid and limited. For our friends living on the Southern side of the Equator, the phrase, Summer of 2020, may not sound right because it is the winter for them. I totally acknowledge this reality but would request them to bear with me on this matter with regards... Click Here to Read Full Article […]

Radio Systems

Fundamentals of Amateur Radio Systems Take a look at some of the fundamentals of the amateur radio system. Technologies related to radio systems for communication have developed rapidly over the last seventy-five years or more. World war II was the turning point. Even prior to that, amateur radio operators were at the forefront experimenting, working with new ideas, and developing new methods of modulation to increase transmission efficiency. With limited resources in terms of transmitter power and the hunger to reach further and further brought about the concept of SSB radio. Initially, it was not taken seriously by the commercial world who continued to use the time tested AM. Eventually, the merits of SSB stood so tall that it could no more be ignored. Now almost entire HF radio communications whether military or commercial radio systems are all done with SSB. This was followed by big developments in VHF/UHF and microwave technologies. The advent of satellites opened up new avenues and satellite-based communication systems become a vital cog in the giant wheel of radio systems communication. Genesis & Evolution of... Click Here to Read Full Article […]

Radio Transceiver S-Meter – Pitfalls to avoid

Radio Transceiver S-Meter – Lesser known facts An S-meter of an HF radio transceiver is a very important instrument on the rig and is used extensively for signal reporting by amateur radio operators while in QSO. However, unfortunately, its calibration accuracy appears to be on the lowest rung of priority for the commercial manufacturers of amateur HF radio equipment. The calibration of the S-meter of most HF transceivers (including several well-acclaimed rigs) is absolutely appalling, to say the least. However, on a brighter note, let us also acknowledge that some of the newer, and modern high-end transceivers that are becoming available these days rely heavily on SDR techniques and often extensively employ DSP to replace various receiver functions that were traditionally done using analog circuits. DSP functions bring to fore several advantages including a far more accurate implementation of S-Meter characteristic response. In this article we will unravel the mysteries, lies, and truth behind typical S-Meter behavior and also dwell into some of the common confusions that are sometimes created. From the perspective of HF amateur radio operators, the ramifications... Click Here to Read Full Article […]