The was the first radio in the series, followed by the S, and finally the SE. He writes “I have located a manual locally VK5 for the AT which by the way, was not available anywhere on the Net, hence my interest in your site I was looking for one. I would imagine a lot of hams would be appreciative for the AT as it is such a workhorse. Well, “amen” to that — I am just such a ham since the AT is what I use here. Not sure of the origin. It is about 8 pages with part list and schematic, if you pair it with the big S service manual you should be all set.. I just October scanned and posted the manual for the Heathkit RF-1 from This should work for the VFO S as well — the S has a redesigned tuning dial, but is otherwise identical.
Inverted U antenna for 160 meters
FM Transmitters Powerful microtransmitter that can cover 3km range. In our case the output power is about mW depending on the input power of 10mW and 9V battery power supply. The transistor Q1 must be mounted with a heatsink, the heatsink must have small dimensions cylindrical in order not to increase the parasitic capacitance. The trimmer R2 serves to adjust the bias of the transistor, start with the trimmer fully open and close by measuring the current absorbed by the 9V, in my case you get mW at the output with a current of 50mA not increase this value as you only increase the absorption by heating the transistor without increasing output power, because the input power is too low.
Clearly the 9V battery will be able to provide 50mA only for a few hours, if necessary have greater autonomy should be used a larger battery, but it is no longer a bug but simply an FM transmitter. FM Transmitters This tiny Mhz FM transmitter bug measures just 10mm x 17mm in size and as you can see in the photos the biggest components are just the microphone and the battery.
This is a simple, portable transmitter operating in the MHz FM band. You may use it to run your own private neighborhood radio, just replacing the microphone capsule with a male audio jack connected to your pc or MP3 player.
Inverted U antenna for meters An Inverter U for the top band Do you find it hard to get on top band because of the antenna? This is a simple wire antenna that may be just what you need. It installs easily, needs no elaborate ground system, yet performs very well. A small ingenuity solves two connundrums at once — getting the current high in the air, and lowering the current in a very simple ground system.
Common problems — antenna too large One way to meet the size problem is by wrapping a loop antenna around the house, tuned to resonance with a capacitor. But a resonant meter vertical is more than feet high. Shorter whips need to be tuned to resonance with coils, and these are lossy. Therefore, most of the power goes into heating the coil and the ground system. Loaded vertical antennas have a current maximum at the ground.
Every ohm of ground resistance is critical, as the I-squared R loss in the ground is lost power. In standard AM broadcast antennas, low ground resistance is accomplished by using a minimum of radials spaced at 3 degree intervals. For amateur work, this is again a formidable undertaking. A bit of ingenuity If a meter whip were made more than feet high, the point of maximum current would no longer be at the ground; its feed impedance would be greater than the quarter-wave 38 ohm value, and would be inductive, not capacitive.
A series capacitor would be needed to bring it to resonance.
Playing with end-fed wire antennas and 9:1 ununs
FM Transmitters This simple mW transmitter broadcasts audio on With good dipole antenna transmission range up to 4km is possible. Frequency is selected by adjusting R1 potentiometer.
Comparison with Dipole. The standard comparison vertical antenna is a vertical 1/4 wave dipole with a ground plane, Using an example model from the EZNEC files with 45degree radials elevated 5 wavelengths, the dipole was compared to the Slim Jim model.
The first thing you need to know is that ham radio has a loooooooong learning curve. You can be a ham for 50 years and still be learning something new every day if you want to. Also know that Ham radio may not be “plug and play” like you may expect! You will have many questions from the start that are not learned in the “books”.
Get yourself a good local “Elmer” who can guide you on your way! What ham radio equipment do I need?
Session Timed Out
My main shack location has a commercial J-Pole Dual band mounted on a short mast. My workshop under the garage needed to have a separate antenna, preferably hung from a nearby tree. Since I like making things, my first choice was a homebrew antenna. Hanging the antenna from a tree presented several conditions such as a symmetrical design that would hang straight vertically and would preferably not require a ground plane system. End fed dipoles have a high impedance at the feed point, so some sort of matching is necessary to keep the SWR down.
In this case, matching to the feed line impedance is by means of a J-match, just like its cousin the J-Pole.
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Class 1 expands the bluetooth range up to ft, breaking thru normal 33ft limits. Without strong signal, audio distorts and cracks, often dropping connection. Go the distance with the RTX and take your audio where you want to go. Audio will stream around corners and through walls, throughout your home, including the garage, pool, backyard, patio and beyond.
A great way to add wireless functionality to your existing speakers or stereo equipment. Trustworthy Reviews and Reputation A flooded market means manipulated, fake reviews by competitors. As vouched for by fakespot. Know you are buying a quality product from a company who cares about its customers and experience. Double your audio opportunities: Use as a Bluetooth transmitter TX mode:
Stealthy / Covert Antennas
End-fed, half-wave antennas EFHWs are a half-wavelength long and are resonant antennas on the band of interest. Generally, they are not usable on bands for which they are not a half wavelength long. End-fed wire antennas are a different beast. In many cases, the impedance can be transformed with the help of a 9:
The above FM transmitter design is a result of many hours of testing and tweaking. The goal was simple; to test many existing BA transmitter designs, compare their performance, identify weaknesses and come up with a new BA transmitter design that improves sound quality, has very good frequency stability, maximizes transmitter’s range, and is fairly simple for everyone to build.
It is exactly as described, in excellent condition, and works perfectly. I have received so many compliments. Paired with my vintage Thorens turntable, it’s an unbeatable match. Great packing, beautiful condition. I’ve been exercising it for the last 6 hours and it sounds excellent! I appreciate the spare lamps for the dial, the test data, the owner’s manual, and your reconditioning effort.
It brings back fond memories of a simpler time, and when products were built to last. I hope other people realize what a really great and cool thing you do by keeping what are likely the best period of electronics in my opinion alive. I found a CA and my setup is complete! You are the best! Unpacked it this evening.
Dual Band VHF/UHF Slim Jim Antenna
There is also a wealth of technical information on active loop antennas on his pages. His amplifier kit is an excellent value and has worked out very well for me. I have followed the loop construction guidance on the site. In fact, mine measures at 1. It is mounted on a 2 M mast and sits on a TV rotator allowing remote control from inside the shack. Why a new antenna?
Above: This gutter antenna is connected via an upper roof-level downspout where no personal contact is possible. This all-aluminum gutter is fed with coax with an unterminated shield (at this end, shield connected to radio ground at the other) to reduce nearby computer hash from inside the house.
The circuit is rather simple, uses only one transistor and few passive components and performs well in terms of frequency stability, almost zero drifting after about 4 hours of continuous operation. With 12 volt DC it will deliver 1 watt RF power. The most important parts of the oscillator are the transistor Q1 and the tuned circuit, which comprises the inductor Ll and the variable capacitor CV1.
When the battery is first connected, a brief surge of current flows from the collector to the emitter of Q1, causing an oscillating i. An oscillating voltage therefore appears at the junction of Ll and CV1. The frequency of the oscillation depends on the values of Ll and CV1, so that varying the value of CV1 tunes the oscillations to the exact frequency required. In order to achieve a high output level, you will need a well tuned antenna, and a large heatsink to dissipate the heat from T2 transistor.
Transmitter was mounted in metal enclosure and works extremely well. Frequency adjustment is accomplished with MV varactor diode and R7 10K potentiometer.