I am feeding that box with 12 volts, and it has a sequencer board, some external relays to drive the coaxial relays, preamp and the amplifier. As you can see, this sequencer board has some DIL relays, they are only intended to drive external relays that actually control all of the above. There are indeed more relays on that board than needed, but the
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boards are "generic" and I use similar boards in other placesof my EME station. The one I use for my 432/1296 station switches both 12V and 24V, and then I make use of all relays on the board. As you see in the circuit diagram, one 741 is for activating the antenna relay, with a delay on break to make sure there is no RFwhen switching back to receive. The other741 is for delaying the keyingofan external amplifier, and it has instant break to stop the transmitter/amplifier. The sequencer is connected to the CAT/Tuner connector on the back of the FT-897. I use the TX Gnd to activate the sequencer via a DIL relay on the sequencer board. Remember, the sequencer 741`s are triggered by a +12V impulse. I also route the +13. 8V available on the same connector, via a 1. 5k resistor, to a set of contacts on the relay that keyes the external amplifier and then back to the pin TX Inhibit. When this pin is held high, no RF comes out of the radio on any band. This way, no RF can be transmitted from the FT-897 before the amplifier is keyed, and this also makes sure that the antenna relays are engaged properly. Actually, no RF is coming out of the FT-897 unless the sequencer is actually keyed properly, which has proven to be fool proof, so far. It might look and sound complicated, but it is not. describing it in words is complicated. No preamp has ever been blown because of sequencer failure. so far.
This project fits more for custom made battery casing that can have more space to hide things inside. This switch with few alterations can be used for any other project as well but is designed based on e-bike needs! This project use a clever functionality of....
The circuit described here uses ultrasonic oscillations and operates based on the propagation velocity of these oscillations in the air. Thus, we can easily determine the distance of two points if the time within which the wave travels this distance is....
Sometimes the precious metals are hidden too deep and are not detected except with complicated devices. In many cases, however, small pieces of precious metal buried near the surface can be detected by relatively simple means. Everyone is very attractive to....
Many times for various reasons we forget or can not water the plants that we have in our homes. And many humidity sensors units just notify us with a beeping sound or with a flashing light, that the pot needs watering. But what if we are away from home? This....
The principle behind a metal detector is really very simple. Proof of this is the circuit that follows, in which it proves that the construction of a metal detector can be done in the minute, with few components that we find very easily everywhere. With the....
The sub-harmonic bass generator is a sound producing unit for guitars. The sound it produces looks very much like that of the bass guitar. The octave generator is sometimes quite unusual since it does not produce any of the usual ways of coloring the sound,....
In the past the sounding (sea bottom measurement) was done with the "bullet", that is, with a heavy lead object that the seamen plucked into the sea hung from a calibrated rope. As soon as the "bullet" reached the bottom, the depth appeared directly from the....
This Amplifier was designed to have the following specifications: Distortion less than 0.1% at full power of 100W even at 20KHz. Power has to be attributed to an extended bandwidth. The output transistors must be protected against short circuits. The power....
A series of LEDs serve to alert the gardener when plants need water. Using two conventional digital integrated LEDs and a series of LEDs, we make a very useful device for gardening. The device detects the amount of water in the pot and alerts the grower.....
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