I want to get into this subject because it is important to good audio practice. This article is actually a second part to another article called “Microphone Frequency Response” which should be read first to fully understand the audio that radios and microphones are capable of. Reading that article first may clarify some of the statements made here in this article.
Heil PR-781 Microphone
This is one of those mics that only comes around once in a blue moon. Because of it’s quality and price, I thought it deserved a mention on my website. Read on and see what makes this mic so special.
When Icom came out with their new IC-7800 elite ham radio, they asked Heil to make them a mic that would really show off the high end audio quality of their new big expensive radio. Heil first made the PR-780. and it was good. Then Heil went a step further and made the PR-781. The 781 is a slightly improvement on the 780. Continue reading
Communication Speakers
Have you searched and searched for a good speaker for your ham radio?
That perfect speaker that would let you hear voices through the noise and static without hiss? A speaker that isn’t fatiguing to your head after listening for a while to weak signals? If you are like me, then you answered yes.
There are several speakers on the market designed for communications. A lot of us long time operators use a good set of headphones to hear those weak signals, or to just enjoy the clean crisp audio of the strong signals. Headphones are probably the best for this purpose, but they can get annoying after wearing them for a while. I was using a small but good quality bookshelf speaker designed for lower powered stereo systems. It sounds pretty good, but it’s still not what I want.
The Grid Yagi
The Grid Yagi (or Grid Quad) is a high performance yagi antenna that can be built with readily obtainable inexpensive materials. Described here is a 6 element 2 meter version with a boom length of about 1 wavelength.
The boom is made of 11?2 inch pvc pipe, although any suitable material can be used, such as steel, aluminum, fiberglass, or wood. The elements are cut from 2 inch by 4 inch galvanized welded wire fencing, with a wire diameter of 0.078 inch, which is what #14 steel wire becomes when it is galvanized. Continue reading
ISS Amateur Radio Shack via Google Maps
ISS walk around via Google Maps
Today, while I was playing with google map, i ended up inside the International Space Station.
I immediately realized thay all the ISS modules have been made available in 360° view, so I decided to look for the ISS amateur radio transceiver, from where astronauts use to talk to schools via the ARISS program.
After some minutes, I spotted the location of the ISS radio shack, that is composed simply by a Kenwood TM- D700A transceiver, and is located in the Zvezda Module of the ISS.
Try yourself
If you want to virtually walk inside the ISS, just follow the link to the Google Maps ISS Radio Schack
The Kenwood TM-D700A is a dual bander that allows APRS, GPS and SSTV transmission with 50W RF Output
The ISS configuration map will help you on orientation through the labyrinth
Quickie Vertical
Quickie Vertical
Hear I am sitting in front of the rig listening to everyone working CQ World Wide, and I don’t really have time for this, but I hear a few interesting stations on 20 meters and try to call them. Trying to bust the pile up with 100 watts and my hustler dipole is going to be difficult on this band, so I tune up on 15 meters and there is action, and I have a good wire beam, so I tune up and down the band and can’t find a clear frequency. Then I hear some one say that 10 meters is open. So I tune up there, and there is a world of DX coming in. I choose a few interesting ones to call, but can’t be heard. I should have expected that, as my antenna for this band leaves much to be desired. It is a vertical above my Hustler dipole, but it has no effective ground plane and SWR no better than 3:1 at its best frequency. With no time to assemble a Quad, I start thinking about a better vertical.
About Loop Antennas
2.4 GHz Cubical Quad Antenna
2.4 GHz Cubical Quad Antenna – Introduction
The Cubic Quad antenna is a commonly homemade antenna in the range of about 150 odd MHz. Our little project was to design one of these for use in the 2.4GHz range for 802.11 wireless LANs. The reason these are seldomly used for 2.4GHz is the size.
The picture below is a 4 element cubic quad for the 147MHz range. Large isn’t it.
The one we are going to build for 2.4GHz will only be 6cm long!
My LoTW Certificate expired – It did it again!
Today I’ve been able finally to make some new QSOs on the air after a short period of QRX.
At the end of the day I decided to upload new QSOs to Lotw fom my RumLog (Mac OSX logbook by DL2RUM), but as soon I clicked on the menu command to “LoTW Out for the selected QSOs” I got the “TQSL Error” message:
I immediately remembered that this happened to me some years ago (3 years ago)
Antenna Basics : Directional Antennas
Directional Antennas
An antenna is known as “directional” if its pattern strongly favors a certain direction. A directional works by concentrating the signal in one direction at the expense of other directions. It is also commonly referred to as the “Beam” antenna. I am going to start with the earliest type of beam discovered, the “Yagi” Beam. This type of beam was discover by Professor Uda but the english translation was done by Hidetsuga Yagi. This design goes back to the 1920s! One would think today there would be better designs. I believe there is, and that’s why I am so interested in antennas!
The Yagi Beam
The yagi is very simple. The basic yagi consists of three elements, as shown in figure 1. The middle element is an antenna you are already familiar with, the simple 1/2 wave dipole antenna. This element is generically called the “driven element”. This is because this is the only element that is connected directly to the radio, it actually drives the whole antenna. The other two outer elements are generically called parasitic elements. One is called the Reflector (some CBers call it the “back door”) and the other one is called the director element. These elements get their name from the job they do. The reflector reflects RF energy, the director directs RF energy. There is no magic circuit located inside the elements, they are simply straight rods! The reflector element is typically 5 % longer than the driven element and the director is typically 5 % shorted than the driven element. How it works. See figure 1. As signal A comes in it strikes all three elements hence generates a current on each element. Remember we said that current on a wire causes it to radiate? Even though the current is very low, this current induced on the antenna actually re-radiates off the antenna again! Ok, back to the action, the signals are re-radiated by the director and reflector and arrive at the driven element in-phase with one another (the two re-radiated signals and the original signal). This basically means, the signals reinforce each other…and make the incoming signal much stronger coming from direction A. Continue reading