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Questions tagged [electronics]

Questions which involve the properties or applications of individual electronic components.

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0answers
21 views

ADS Simulation: Why could not the diode do the rectification? [migrated]

As titled, the diode in my half-wave rectifier did not rectify the AC signal. Vd1 is still AC signal. Therefore Vout ~ 0V. Why could that happen? The diode's parameters are SPICE parameters. The ...
3
votes
2answers
216 views

Share wide band antenna with multiple transceivers

I'm trying to incorporate several transceivers on my board design; I need WiFi (2.4 GHz) SatCom (~1.6 GHz) RF (~900 MHz) and GNSS (~1.5 GHz). I need to combine them into one antenna. I found a wide ...
7
votes
2answers
91 views

Water cooling a GS-35B in lieu of air cooling?

Does anyone know how to --or have any experience with-- water or oil-cooling the anode? Since forced-air cooling is required, the sound from the blower and the exhaust air would be too noisy for my ...
6
votes
1answer
141 views

How to determine number of turns for a 1:1 balun?

I would like to make a 1:1 balun with М1000НМ ferrite core (magnetic permeability - 1000) and 1 mm thick copper wire using triple bifilar winding. Unfortunately I didn't manage to find a clear ...
1
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2answers
197 views

Why does a Class-C non-linear power amp distort SSB but does not distort AM?

Can someone tell me why exactly a transistor non-linear power amplifier will amplify an AM signal without noticeable distortion, but will distort an SSB signal, giving the familiar scratchy sound ...
6
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2answers
450 views

Feed-through Capacitors

I'm in the "information gathering" phase of a RF Power Meter project and the design I fancy (W7ZOI Power Meter) calls for a feed-through capacitor at the output port. I understand that a feed-through ...
5
votes
2answers
97 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 ...
6
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0answers
63 views

UHF FM power amplifier design without expensive software

I'm designing a small UHF data transceiver for the 70cm band, based on a Silicon Labs EZRadioPro Si4463 IC. Modulation is FM, 12.5kHz channel step. The concept is similar to SiLabs' AN656 application ...
5
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0answers
83 views

Beyond Maximum Stable Gain of a transistor

I was plotting constant-gain circles on the Smith chart the other day for a potentially unstable RF transistor. I recently read on-line that for a potentially unstable transistor the maximum gain ...
5
votes
2answers
182 views

Learning RF electronics

I've been studying and building test circuit for actually several YEARS now, so far with no success. It sounds ridiculous but it's true. So I feel like I have a good understanding or RLC circuits, I ...
0
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1answer
41 views

Reflection Coefficient to Impedance transformation on the Smith Chart

A certain RF transistor has a source - reflection coefficient with a magnitude of .105 and a phase angle of 160°. When plotted on the Smith Chart, the normalized impedance is .825 +j .06 Ω. What is ...
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3answers
99 views

I just got this RF equipment but i don't know what's for

I got some RF equipment for free (it was going to the trash and I 'rescued' it). It's almost new, and seems expensive, but i don't know it's purpose. Googling the model numbers yields very little ...
3
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2answers
180 views

What's the difference between a Return Loss Bridge and a Circulator?

From my understanding a return loss bridge basically consists of three terminals: an RF input, a DUT output and a RF output which goes to say a spectrum analyzer; I understand that the RF input signal ...
3
votes
1answer
84 views

Series resonant circuit, how to calculate voltage across the capacitor?

This is question a3i3-1 from the practice questions in the book "amateur radio Exam Secrets": A series resonant circuit has 10V peak across it when at resonance. At that frequency the resistance of ...
2
votes
1answer
58 views

Inductors for Impedance Matching

I need to impedance match an IF mixer circuit to a 10.7MHz crystal filter. One of the inductors was calculated to be 44 $\mu$H. So I need a relatively large value inductance in a small package to fit ...
5
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2answers
136 views

What is Norton's transform?

This article from Itchen Valley Amateur Radio Club describes an interesting technique called "Norton's transform": This results in a negative capacitor, but in a circuit where there are other ...
1
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1answer
82 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? ...
3
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3answers
58 views

Conventional or electron current

I’m reading a radio theory book, Radio Theory Handbook by Ron Bertrand VK2DQ, which suggests that electron flow (ie current flowing from negative to positive) is used in radio theory and design. In ...
8
votes
3answers
383 views

Why are germanium diodes specified in amateur radio designs?

It's somewhat common to find a schematic that calls for a germanium diode in amateur radio contexts. For example: This is a QSK circuit from the Fldigi manual. And yet, purchasing a germanium diode ...
2
votes
2answers
197 views

Can anyone please suggest a substitute for the BFY51 transistor?

I have to replace a faulty BFY51 Transistor. I could not find one in the market since they have been discontinued. What is a suitable replacement?
1
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3answers
156 views

Easy way for an uncertified hiker to broadcast a distress signal

I am wondering whether shortwave can be used as an effective distress call for a hiker who is a non-ham operator. More specifically, Are non-certified operators permitted to broadcast distress calls ...
4
votes
2answers
130 views

Is using a DDS chip directly a viable way to transmit 2FSK and PSK on HF?

I'm thinking of building an HF transmitter for data (AX.25 or PSK31). Rather than using an IF stage, I'm thinking of generating the RF frequencies (or phases) directly with a Direct Digital Synthesis ...
2
votes
1answer
1k views

How to find or derive the maximum safe input power to a receiver?

A number of my RF devices have a specified safe maximum input power, for example: "The maximum RX power of HackRF One is -5 dBm. Exceeding -5 dBm can result in permanent damage!" source "If you look ...
4
votes
3answers
245 views

Why is coax loss logarithmic?

With DC hookup wire, losses are directly proportional to length. If the resistance of 100m of wire is 10 ohms then the resistance of 200m of wire will be 20 ohms. But we measure coax loss in decibels ...
1
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1answer
230 views

Old Yaesu FT-470 HT audio feedback with external speaker mic

I have a generic external speaker mic with the two-pin connection (1x 3.5mm, 1x 2.5mm mono jack), which doesn't work with my FT-470 (no real surprise, figured I'd just mod it.) I've started the mod, ...
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1answer
54 views

WIFI PACKETS AMPLITUDE AND DISTORTION [closed]

How is it that a computer receiving packets through wifi doesn't get those wifi packets distorted often? Wouldn't things like other radio waves interfere with the signal often? How does my computers ...
4
votes
2answers
145 views

In the context of the mixer in my radio, what does balanced and unbalanced mean?

I'm trying to understand how the mixer in a radio actually works, at a physics level. When looking at this article and studying the first schematic I realized I really don't understand what balanced ...
0
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2answers
525 views

what are the alternatives to LM387 and SA602AN?

I am building a 20 Mhz RF receiver out of the NASA radio JOVE instruction manual and they have recommended the use of LM387 as an audio amplifier. SA602AN as mixer IC:
2
votes
0answers
90 views

What protocol does the Vertex VX-2200/2100 use for programming?

I have seen a number of programming cable schematics on the internet, but I couldn't understand very much how they worked. From what I picked from all schematics, it appears the protocol uses the <...
4
votes
3answers
2k views

Good FM receiver single-chip IC for simple VHF receiver?

Is there an IC out there that implements all, or most all, of a simple FM receiver in the VHF range? I'm interested in doing some experiments with using DTMF over the air for tele-commands and the ...
2
votes
2answers
189 views

Adapting an antenna tuner for use with a panel meter instead of an LED

I'm building NorCal's / W6JJZ's BLT tuner (pdf) for use on 40m/20m with a 5W transmitter. I would like to remove the LED and use a small panel meter instead. I don't have a 1N34A at hand, but I do ...
3
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2answers
112 views

Building an IQ mixer using an in-phase LO splitter

There are many examples of IQ mixers on the internet; all use 90 degree hybrids to split the LO to the mixers with the outputs being combined in-phase. I'm curious, could both mixers be fed an in-...
4
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3answers
2k views

How should this SWR meter's directional coupler work?

I'm wrapping up a "home build" of the MFJ-941EK antenna tuner kit and having trouble getting the wattmeter calibrated. I can't use C4 to get the reflected power reading calibrated down to 0 as is ...
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0answers
78 views

Practical Resources for the Amateur Radio Student? [closed]

What electrical circuits can be easily build by someone with basic electrical engineering skills that exemplify the fundamental components of radios, antennas and so on?
3
votes
3answers
98 views

Switching 450 Ω window line

I have a very old Harvey Wells Z-Match antenna tuner (transmatch) with two outputs on the back for 450 Ω window line. One output is for “medium frequency” and works for 75 and 40 meters. The other ...
8
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3answers
2k views

Why does “high SWR” damage transmitters, instead of “impedance mismatch”?

In the audio realm, where cable lengths are insignificant compared to the signal wavelength, I would understand an impedance mismatch damaging an amplifier as follows: Take an audio amplifier that ...
1
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2answers
197 views

RF6886 high power amplifier maximum reverse power

I'm designing a circuit which uses the RF6886 amplifier IC. What is the maximum reverse power that the amplifier can sustain? At what reverse power will the amplifier die?
2
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1answer
185 views

Basic Signal Detector using MOSFETs

I am trying to design and build a basic signal detector using MOSFETs because they are more compact than resistors, capacitors, and inductors. I was wondering if anyone here has any suggestions on how ...
2
votes
1answer
446 views

Adding a panadapter via SDR

I've become very accustomed to the waterfall display on my SDR, especially for digital modes over HF. I'm thinking about tying into the IF on my IC-718 and connecting to an SDR to add a waterfall to ...
1
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0answers
38 views

Relay cross reference for 1925-3-2

My amateur radio uses 1925-3-2 relays on the low pass filter board to select bands. This relay is no longer available. Is there an alternative I can use? Or something?
1
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2answers
182 views

I need help identifying what I believe is a military radio

I'm hoping this question is okay to ask here. While this question is not strictly amateur radio related, I think this is the best community to ask. I'm looking for any information on this. ...
0
votes
1answer
67 views

What is the required signal-to-noise ratio for a AX5042 transceiver?

What is the required signal-to-noise ratio of a AX5042 transceiver IC?
1
vote
1answer
130 views

Toroidal inductor and transformer basics

In basic terms, using an Ultimate3S Beacon (above) as an example, what do the various toroidal components do exactly? How do they accomplish this? In construction terms, does it matter if the wound ...
6
votes
2answers
433 views

Simulating two antennas (transmitter and receiver) using 4nec2 tool

I am trying to find near field mutual coupling affects between two antennas - one being transmitter and other being receiver. The receing antenna is fed with very little voltage (I think, if I don't ...
1
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0answers
51 views

Transformer secondary coil impedance [closed]

To transfer maximum power from the secondary coil to the load, I need to find secondary coil impedance. My load impedance 5 - J365. I would design a matching circuit between load and secondary coil, ...
1
vote
0answers
206 views

What will be antenna impedance of a dipole antenna when it is kept lambda/2 away from the transmitter

I understand that half-wave dipole antenna, which is in far-field, impedance is around 73 ohms. If I keep same antenna in near-fied at distnace lambda/2 from the 1.25 lambda length tranmiter?
4
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2answers
171 views

New to Amateur Radio [closed]

I'm new to radio, and I'm trying to get into the electronics aspect of it. I was wondering if it was at all possible to build your own transmitter, receiver, etc. (basic radio components) as good ...
0
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1answer
82 views

What would happen if I created this circuit? [closed]

As you can see, one of inputs of a XOR gate is connected to the output of the same XOR gate. Each time when the output is "true" it influences its input and it makes the gate change output to "false". ...
0
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1answer
918 views

Chip with price and functionality to the RDA1846?

Is it possible to buy a cheap transceiver chip with similar functionality to the RDA1846? I'm looking for something else, because I'm wary of buying a probably counterfeit chip on AliExpress, and I ...
1
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1answer
71 views

How do I integrate XStream RF modules with any microcomputer (Rasp Pi, Beaglebone)?

I have selected XStream RF modules due to their price and their range (7 miles). I am part of a car team and hence need to transmit and receive data between the car and the ground station (follower);...