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23 Threads found on Hf Oscillator
Hi, This little crystal oscillator I have designed by trial and error, uses crystals or ceramic resonators to oscillate at HF. There ia a "hitten" capacitor formed by the internal capacitance of the gate-source of the FET. When I set the source trimmer at extreme ends (especially at low values, max OSC gain) the oscillator changes frequency by a f
Hi, I would like to build this little transmitter I like the fact that it is screen modulated and uses no anode transformer. I wonder if I use a linear output amplifier, would I need to perform the modulation on it, or at the tube oscillator as is? My HF commercial transceiver (that has linear amplif
Hi, this is a simple HF TX (it's core) that I have found in an old HAM magazine. It outputs about 5-7W depended on the band (160m-20m or so). I do not like the fact that it uses PNP transistors for the oscillator and that it keys the oscillator. Also the RFC must have a 30R series resistance, so it is critical. Can you help me modify the circuit
Hi a question has come into mind related to these HF HAM commercial transceivers. How do these handle the SSB and LSB related to the oscillator frequency? I can think of two cases. It is better to present an example, to understand my question. For both cases LOSC=10MHz and transmitter baseband modulating audio signal=1KHz tone. Case 1: When switc
Hi there, I have found measuring RF power a tricky thing to do if not special equipment is available and I would like your comments on this. I have an HF power oscillator that is supposed to output 2W. When I measure this in the watt meter it outputs 2W. When I measure it in the scope, it outputs about 28Vpp ie 2W, and the waveform seems somehow
What is the load on the oscillator and where does its current return? The two grounds are evidently distinct and you need to have a good HF return path or you will drop voltage all around "whatever the loop is".
Hello I consider this it produce 90 degrees phase difference between it's outputs or 180 degrees? Is it possible to scale it for HF frequencies? <30MHz A converted crystal configuration could also
Hi I have made a power oscillator for HF using an RF transistor that is mounted onto a metal enclusure that is used as a heatsink using mica insulator to insulate it from the enclosure (fin connected to collector) The emitter of the transistor is connected to ground and the metal enclosure is not connected to ground. When I touch the metal enclosur
Hi, I consider the MC1648 as an oscillator in LC mode for HF CW transmitting. I would like to know to things: 1. What sort of output power and impedance should I expect out of it? (in order to see what will be the drive to the power amplifier) 2. What sort of frequency stability should I expect out of it? Is it enough for CW transmitting on HF am
Hello, I am a bit confused of which material is better to use in a 7MHz HF oscillator I make. Amidon specifies material 2 for 2-30MHz and 6 for 10-50MHz However the next site specifies material 2 for 250 KHz-10 MHz and material 6 for 3MHz-40 MHz The material 2 material 6
Hi I would like to make a small TX transverter from 144mhz to 14mhz and 7mhz. Instead of mixing, which requires a stable vhf oscillator, I was thinking of a divider, which divides the stable 144mhz signal to hf. for 14mhz a mc12080 can do a simple /10 divider but what about 7mhz? Any other propositions for dividers for 14 and 7mhz would be helpful.
Hi I am building an HF oscillator circuit which requires a bf247c but this is not cheaply available. Are there any equivalents?
Hello, I am thinking of the attached Quadrature oscillator covering 1KHz-30MHz, and I wonder if this would work and if it will be stable enough to be used on HF ham bands? (as it is, no decreasing of the range) I do not expect crystal stability, but I have read that the thermal stability of these chips is 40ppm per C! Also the max freq of the
If this is a normal crystal then this will specify a capacitive load for typical operation. The problem will be that circuit layout is unknown and produces a significant capacitance. The two capacitors for HF work are often around 10pF, hence the layout issue. Keep the crystal leads close to the component pins, track the capacitors close to the
Hello, I came across this HF band kit that says hooking up will enable you to receive HF bands ...30m, etc basically i want to receive 10 MHz signal (which is not in 30m band) but this kit is programmable with software (so its a Software defined radio), t
I made a HF pedal for my welder with an illuminated footswitch. I wired it up by trial and error, and it sort of works, but I don't know why! The foot switch makes a circuit for a secondary output primary coil which energizes a spark gap oscillator that generates high frequency bursts of high voltage to help start the arc. The LED lights up whe
Hello I am trying to make a simple RTTY oscillator for the HF bands that can accept 1.2KHz and 2.2KHz audio tones. Can this be done using a quartz crystal for better stability, or the crystal does not allow so much deviation? Also are there any sources of such a schematic?
Hello I alter the frequency of an HF (1-30MHz) crystal oscillator using an MV209 varicap. I need to replace it with a greater capacitance range varicap to increase the tuning range, as much as the crystal permits it. Which one should I use? Requirements: 1) 9.5v maximum tuning voltage 2) junction operating temperature more than 80C, since it
Hi every one, I do not know if I am in right topic section. I need some schematic circuit diagram of an HF Plastic welding machine (for creating Photo Albums). I want to assemble one for me by using FU 501 triode as the main oscillator/output tube.
Hi Chaps, I have built a hf start module for a tig welder, its basically a high voltage radio frequency spark gap oscillator driven by a car ignition coil, its aim is to start the arc from the electrode to the work esp on low welding voltages. It works well on my dc output alternator generator welder, however I tried this device on a ac stick w
You will be best off by using inductive coupling. Especially if everything is in a large metal box. In the EU there are rules on unintentional radiation in the HF ISM bands. You can exceed these with just tens of watts of power.
Hi I need some help..Ive been trying to build a RF amplifier for 12MHZ .But ive had some problems driving power. The basic oscillator is a colpitts one with crystal using a BJT 2N2222 .Output is taken from BJT colector.The bjt colector also has a choke tied to +Vcc.But I need to boost output power. Just 1 BJT isnt enough for getting 180Vpp and 20
The problem is tricky - he wants to have consumption about 3 microwatts . So oscillator must be very efficient , that put restriction on using UHF, which is preferred for such communication - antenna lenght could be very small) I think you can experiment with ferrite antennas on LF-HF band to keep power consumption low. Or may be usltras