Skip to main content

Questions tagged [oscillator]

The tag has no usage guidance.

Filter by
Sorted by
Tagged with
1 vote
1 answer
29 views

The Maximum Power of Quartz Oscillation?

Quartz oscillation is well known for its high Q-Factor and stable frequency. I have read many articles which say that amplifying such quartz oscillations should not be easy. I am not a licensed radio ...
noneed's user avatar
  • 113
-6 votes
1 answer
207 views

How low can a VCO step up and down frequencies?

So I am a hobbyist and I have in mind, a project I am working on and I need to sweep in a frequency range of 500 MHz with a step of 500Hz, and if my calculation is correct, this is equal to 1000000 ...
user avatar
-1 votes
1 answer
76 views

How does a band frequency is generated?

A band frequency is a range that start from a X frequency(lower one) to a Y frequency(higher one) but exactly and precisely how this is done i dont know how.i assume that the generator use a loop step ...
user avatar
5 votes
2 answers
865 views

How to design a Local Oscillator for a radio receiver?

I have decided to design a Medium Wave radio with discrete parts which won't include much complex ICs or schematics . I am thinking of designing the radio in Heterodyne mode. Which requires an ...
CoderBittu's user avatar
3 votes
1 answer
118 views

Will two GPSDO units be precisely in phase with each other?

I always thought of a GPSDO as only a precise frequency reference. But the GPS and other GNSS systems also deal with rather precise UTC/TAI-ish time! Are the outputs of any two GPSDO units generally ...
natevw - AF7TB's user avatar
5 votes
4 answers
594 views

How can I inject an oscillator output into the RF input to my radio?

I have a Bodnar GPS disciplined oscillator, and I would like to inject its output into the antenna input to my HF rig. This will allow me to compare the frequency of received unknown signals to the ...
Bill KG5RMJ's user avatar
1 vote
4 answers
306 views

How can an RF coil emit at 3 different frequencies at the same time during Amplitude Modulation?

This image shows how an AM wave is generated and emitted: This comment explains how 3 separate waves are sent at once to represent an AM wave: the transmitter does not transmit one pure sine wave at ...
Dan's user avatar
  • 311
2 votes
0 answers
207 views

Dielectric coaxial resonator vco circuits topology?

I came across this VCO that uses a dielectric coaxial resonator, I understand how the resonator works, what I don't know is the oscillator topology, Colpitts, Clapp, et. Also I do not see any circuit ...
mpradio's user avatar
  • 75
6 votes
4 answers
1k views

Can SDR receivers be detected remotely?

It's my understanding that active superhet receivers can be detected by looking for the emissions from the local oscillator, particularly because the LO's frequency is usually set at some fixed offset ...
chrylis -cautiouslyoptimistic-'s user avatar
5 votes
3 answers
339 views

Design of oscillator

I'm looking for a good tutorial about oscillator design (electronically) for transmitter. The problems with current tutorials are almost all provide only schematics, some explain how it works. But ...
RainerJ's user avatar
  • 151
2 votes
4 answers
871 views

How to use FE-5650A rubidium frequency standard?

I bought a FE-5650A rubidium standard reference from eBay in the hope I can readily use it: https://www.ebay.com/itm/142361240786 Unfortunately this is far from "reasily useable". First and ...
divB's user avatar
  • 163
1 vote
2 answers
140 views

Toroid Coupling Issue in Common-base Amplifier

I'm working on an old school VFO for the 15 meter band based on a JFET Hartley oscillator. The plan is to follow the oscillator section with a JFET buffer, then a CB amplifier (for increased reverse ...
Buck8pe's user avatar
  • 989
11 votes
1 answer
2k views

Why would you need a signal generator to receive early satellite transmissions?

I recently watched, on You Tube, a NOVA program about the British school masters and students who were the first to publish the news that the Soviets had started launching satellites from a new launch ...
John Warren's user avatar
6 votes
2 answers
2k views

Is there a best ratio of L to C in a resonant circuit?

When designing a resonant circuit, for example as a local oscillator, the product of $L$ and $C$ determine the resonant frequency according to $$f_{res} = \frac{1}{2\pi \sqrt{L C}}.$$ This means that ...
DK2AX's user avatar
  • 624
3 votes
3 answers
389 views

78.5MHz AM receiver self-oscillation

Circuit appears to be working but very easily breaks into oscillation - sometimes just getting up from my desk triggers it, or while tuning, and sometimes after a few seconds with no disturbance that ...
user avatar
2 votes
1 answer
210 views

How does this Pixie circuit produce a beat frequency?

I have two Chinese Pixie kits that I've assembled. I think they are pretty interesting, from a QRP / tinkering stand-point. Looking at the schematic below, where is the beat frequency coming from? ...
Will B - AF7EC's user avatar
1 vote
1 answer
166 views

Frequency divider in premix oscillator (PMO)

In his book "Crystal Sets to Sideband", Frank Harris K0IYE describes using premix oscillators (PMOs) to convert signal from low-frequency LO to a particular ham band. Many ham bands are harmonically ...
user6691's user avatar
3 votes
5 answers
1k views

"Local oscillator generates a frequency twice lower than received signals". Why and how does it work?

I would like to construct the following receiver: I have a fair knowledge about a receiver building blocks. I have previously build small receivers. In the description it say: The local ...
machineaddict's user avatar
7 votes
4 answers
3k views

Shaving Quartz Crystal for New Frequency

Back in the 1960s during my Novice days I operated on the 40-meter band only with 4 different quartz crystals that determined my transmitting frequency with my Eico 720 CW transmitter. I had heard ...
K7PEH's user avatar
  • 3,008
3 votes
1 answer
538 views

How can I tell the frequency without an oscilloscope, or frequency counter?

Just going through the RF oscillator listed on SM0VPO's web-site. I replaced C1 by a reverse biased 6A8, and used an E-core transformer pulled out of a Compact Fluorescent Lamp instead of an inductor ...
VU2NHW's user avatar
  • 2,834
4 votes
3 answers
2k views

SSB demodulation

I was building the superhet receiver for ham radio. But I seem to have got stuck at the demodulation stage. As an example: Suppose the person is transmitting SSB signal (20m band) at 14.250 MHz ...
Plutonium smuggler's user avatar
7 votes
2 answers
829 views

Doppler Shift Compensation in Inter Satellite Communication

I am currently doing a project in the area of optical inter-satellite communication (GEO-LEO). I am using a optical carrier of 281 THz, and the Doppler shift corresponding to it is ±7 GHz. I ...
Seetharama's user avatar
6 votes
2 answers
372 views

Does the waveform of the VFO necessarily have to be sinusoidal?

Looking around for a VFO online, I see most kits/manufacturers make it a point to mention the waveform. Sinusoidal is a fundamental shape, whereas others (sawtooth, square) are a composite. I recall ...
VU2NHW's user avatar
  • 2,834
3 votes
1 answer
611 views

Can an external VFO be injected into a commercial rig?

Constraints of various kinds preclude any investment in a rig at present; so I find myself pondering the means to get back on the band piece-meal. Say I were successful in an attempt to throw ...
VU2NHW's user avatar
  • 2,834
10 votes
3 answers
6k views

Why prefer LC oscillators rather than RC oscillators in RF design?

I don't recall ever seeing an RC oscillator driven RF transmitter or receiver. What prevents people from choosing RC oscillators in RF design?
Adam Davis's user avatar
  • 12.2k
1 vote
1 answer
104 views

Can I filter after modulation when using a square wave oscillator? [closed]

Most designs appear to filter most of the harmonics out of the oscillator before modulation, then apply additional filtering as needed for the specific modulation they are using after modulation. ...
Adam Davis's user avatar
  • 12.2k