- #Radio shack manuals archive manual
- #Radio shack manuals archive full
- #Radio shack manuals archive plus
Simply say that if the input voltage (Vjn) is a positive voltage between the upper and lower threshold voltages, the outputs of both comparators will be at supply voltage. It uses two LM311N voltage comparator integrated circuits connected as a window comparator.
#Radio shack manuals archive full
The system that I selected is known as a "bang bang" servo system in aerospace circles, It is either off or on in one direction of rotation or the other and provides full motor torque when on. To understand its operation, it is best to start with an explanation of the servo system and work backwards toward the input. The circuit which I designed is depicted in Fig.
#Radio shack manuals archive manual
The control head has directional indicators, an automatic/manual operation switch, an automatic/manual indicator, a manual slewing switch, and an impedance-match selector switch. Tuning unit also contains a toroidal impedance-matching transformer which ensures a good impedance match between the antenna and coaxial line. The jack is a male chassis-type ¡ones plug. The output transistors and motor are discussed in the text. The motor turns a roller inductor taken from a surplus T21/ARC-5 or T22/ARC-5 command transmitter. The tuning unit contains a phase detector and a servo system which drives a permanent-magnet dc gear motor. One unit is a control head and the other is the tuning unit. These design requirements led to a system consisting of two units.
#Radio shack manuals archive plus
Last of all, the servo system had to be uniquely simple, have a 3-or 4-kHz deadband so it would not hunt or jitter around in the voice pass band, provide constant motor torque while tuning, and operate reliably over a plus ten-to-fifteen-volt supply voltage range. ¡t had to be easy to duplicate, present a pleasing appearance, and the control head had to be capable of being mounted on the side of an Atlas and be visually compatible. The parts count was to be minimized to keep reliability high, complications associated with limit switches were to be avoided, and the power handling capability had to be at least 350 Watts PEP. I decided that the tuner would be required to tune automatically over all of the 40 and 75 meter phone bands and use easily-obtainable parts. This conclusion required me to design a servo system. Luckily, no damage was done, but the experience convinced me that for safety's sake 1 had to get out of the loop.
This worked beautifully for about six months until I ran off a freeway one day while watching a field strength meter as I was peaking the antenna. The base of the antenna and a control switch at the driver's seat, allowing me to QSY the antenna resonant frequency. Specifications for the Tennamatic are listed in Table 1. Of course, if your transceiver has tubes in the final, you will "still have to retune it when you QSY. Start talking, and the Tennamatic will tune your mobile antenna system to resonance automatically, ensuring maximum field strength.
This means that you can use transceivers having solid-state finals and obtain full output power on any frequency in the 40 or 75 meter phone bands without any manual tuning operations. Would you like to operate your mobile station over the entire 40Īnd 75 meter phone bands with a vswr not exceeding 1.15 to 1? With a Tennamatic, you can convert a high-Q narrow-bandwidth mobile antenna into a wide-bandwidth system. To obtain full band coverage, I added a motor-driven roller inductor atī. The control head, tuner cover, and end pieces are 0.040-inch soft aluminum cut in a paper cutter and folded in a vise using wood blocks. The neat packaging of the Tennamatic can be duplicated easily. It also proved to be an exceptionally efficient radiator compared to the commercials, but it was still limited to only a few kHz of usable bandwidth on each band, and I wanted full band
He subsequently described it in his October, 1976, 73 Magazine article entitled "Build a Weird 2 Band Mobile Antenna." His antenna neatly solved the problem of needing to change antenna loading coils when band-hopping between 40 and 75 meters. About two years ago, I met Don Johnson W6AAQ, and ! adopted his "big DK" mobile antenna system.