The back to back diodes are there because some radios present high voltage transients when switching bands which will lock up the DFD requiring it to be turned off and back on to unlock. If power for the backlit display is to be taken from Vdc when AC is supplied to Vac then the capacitor from Vdc to gnd should be increased to about 100ufd to 250u
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fd depending on current supplied to backlit. Piero used a DFD with the IC-202S two meter rig. It triples a 15MHz VXO to 45 MHz and then triples it again to 145MHz. Piero took the signal after the first tripler and set DFD to multiply by 3. The signal was taken from the junction of R25, R26 and C39 through a 100pf capacitor and about 12" of RG174U. I purchased your DFD and it works great. Although to get it to work with my Kenwood TS-820. I had to add an amp to the front end to beef up the VCO signal from my radio. I thought you would like to know that I used a Signetics NE5205 wide band 20db amp. I used two 1000pf caps, one on the input and one on the output. Also a. 01 bypass cap. I taped into the 5volts on your board and I was in business! I did a bench test and the DFD will convert a 50mvp-p signal up to 47Mhz. Which is well above where my radio VCO tops out at. I thought you would like this info and find it useful, if you didn`t already know about this chip. Thanks for bringing my radio up to modern standards. You can also use an NE5204. These devices have a 50 ohm input impedence. An emitter or source follower can be added to the input to increase the input impedence. Direct conversion units are simple. Connect to the LO (VFO) output and adjust the IF offset to zero. The NE/SE602 is a popular device in such units. The counter should be connected to pin 7 (the emitter of the oscillator transistor) Single conversion...
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....
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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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