Questions tagged [electronics]

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

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2
votes
1answer
54 views

voltage rating for RF filter components

I want to design a PCB for a diplexer for Satellite operations. I want to use SMD capacitors and possible inductors to get some experience with soldering SMD components. What should the voltage rating ...
0
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1answer
41 views

Had +5VDC and GND swapped, feeding a GPS receiver. Source is +5VDC output @ DB9 port on Yaesu FT-2600M, now showing 0V. Did I fry something?

Basically, I connected +5VDC to the ground of a GPS receiver, and now have no power from the power source. Is it possible to mess something up by doing this? I feel like this is more of a basic ...
0
votes
1answer
71 views

Can i use an anaolgue IC switch to change a 10 m yagi's directivity by somehow combining received signals with different variable phase?

Can i use an analogue IC switch being triggered at the same frequency I am receiving on to change a 10 m yagi's directivity by somehow combining received signals with different variable phase either ...
5
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3answers
182 views

ARRL handbook as a reference for all your radio learning needs?

Looking to take up learning understanding everything from basic electronics to how today's wideband radios work, so that I can build my own radio systems (not just ham radios), and talk radio concepts ...
1
vote
2answers
54 views

How is frequency selection (tuning) accomplished in a direct conversion receiver?

How is frequency selection (tuning) accomplished in a direct conversion receiver ? A crystal filter can't be used is that correct ? Because there is no IF to mix with the incoming frequency band ...
3
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2answers
95 views

What are the advantages for a receiver that uses an IF compared to direct conversion?

What are the advantages for a receiver that uses an IF compared to direct conversion ?
1
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2answers
97 views

If I parallel two crystal filters together, will that double the bandwidth? [closed]

Will the bandwidth be doubled ? And will the impedance be halved ?
4
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2answers
94 views

Dipole increased CM current using choke balun

My 20 meter inverted vee dipole is fed with 56 feet of 50-ohm coax. The SWR measures 1.2 at the center of the band. According to http://arrl.org/grounding a balanced antenna doesn't need a ground, so ...
1
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3answers
96 views

How does the Maximum Power Transfer Theorem relate to RF power amplifiers?

The Maximum Power Transfer Theorem says that maximum power transfer occurs when the source impedance equals the load impedance, when the power transferred to the load is 50%, the other 50% being ...
4
votes
4answers
177 views

Why does an RF Amplifier fail when the SWR is high?

Exactly why does an RF output transistor fail if the SWR is bad ? Is it A because the impedance mismatch between the transmission line and the antenna results in maximum power not being transferred ...
2
votes
2answers
257 views

Voltage vs. Current Balun for Dipole

I'm a new radio amateur setting up a half-wave 10-meter inverted vee antenna fed by 50 ohm coax. I understand that the inverted vee lowers the normal 72 ohm dipole closer to 50 ohms, so I only need to ...
3
votes
4answers
149 views

How is working on DC high voltages as in a tube radio different from 120VAC?

Suppose that I am familiar with the safety procedures for working on 20 A 120 VAC 60 Hz household lines. What should I be prepared for before working on high voltage DC circuits (say, 800 volts) as ...
4
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0answers
64 views

Is it practical to use a magnetic amplifier as an AM modulator in a transmitter?

If I'm building a vacuum tube HF transmitter (say, 40 m band), obviously the simplest mode to build is CW; it's common to key the oscillator input to the final (in order to keep the oscillator running ...
1
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0answers
59 views

Are jammers relate to electronics or electrotechnics , why? [closed]

Are jammers relate to electronics or electrotechnics , why ? Please ,tell me the main difference between electronics and electrotechins and why we can classify jammers as electrotechics or ...
7
votes
1answer
143 views

Double power-handling ability of RF amplifier output transformer

I want to base the output network for a 500W push-pull HF amplifier on "A 250W Broadband Linear Amplifier" described in Chapter 17 of the 2014 ARRL Handbook. I need advice on whether and/or how the 1:...
6
votes
6answers
379 views

Is it practical to use a slug-tuned variable inductor in an antenna matcher (aka “antenna tuner”)?

I will soon need an antenna impedance match (aka "antenna tuner"), because I'll initially only have a single antenna for my HF rig (needs to cover 80m, 40m, 20m, 15m, and 10m). Obviously, in order to ...
1
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0answers
73 views

How can the output power of a Yaesu FT101E be increased?

I have a Yaesu FT101E which has low output because the final 6JS6C valves are old. If i increase the plate voltage on the final tubes from 600 to 800 VDC by changing the mains transformer tapping ...
2
votes
3answers
141 views

Is double amplitude modulation useful?

If i amplitude modulate an AM carrier with an audio signal, can i then feed that resultant AM waveform into another modulator and amplitude modulate the AM signal to give a signal which is amplitude ...
2
votes
1answer
49 views

Attenuator Cascaded Connection

PAT1220-C-10DB-T5 is a 10dB attenuator. (This chip is just an example, it could be any other component as well). Can I simply connect 3 of them in series in a PCB design to make my cheap 30dB ...
1
vote
3answers
318 views

How to reduce voltage ripple of a linear power supply?

I made a simple linear power supply for my transceiver using 12V 30A transformer, four diodes RHRP3060 forming a rectifier and three 30_000 µF capacitors connected in parallel. I also used a 200 Ω 50W ...
2
votes
1answer
59 views

Can an indoor antenna damage unshielded electronics?

I have a 25w radio running through a ~4.5db gain antenna. If I use a 4W HT indoors, I can hear a loud buzzing noise emmanating from my computer speakers. If I used the 25w mobile with the 4.5db gain ...
-1
votes
1answer
47 views

Skin effect for a modified antenna with a high frequency pulsed DC

A direct current will be interrupted by a high frequency switch. It seems , that in a wire, connected to the source (the antenna rod), instead of pushed back- and forwards electrons, the electrons get ...
5
votes
2answers
267 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
150 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
920 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
vote
2answers
447 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
votes
2answers
598 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
147 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 ...
0
votes
1answer
167 views

ADS Simulation: How to model an antenna in a simple rectifier circuit?

As titled, I'd like to explore the output power of a simple diode-based rectifier circuit, excited by an antenna (assumed to be 50 ohm impedance). Please give me some advice as to how to do this. It ...
8
votes
0answers
136 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 ...
6
votes
0answers
145 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 ...
6
votes
2answers
265 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
votes
1answer
54 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 ...
1
vote
3answers
106 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 ...
2
votes
2answers
410 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
126 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 ...
4
votes
4answers
2k views

What are some equivalents of a BF199 transistor?

I'm planning to build an FM radio receiver using the instructions on http://www.instructables.com/id/Build-your-own-Crude-FM-Radio/ The schematic uses a BF199 transistor which is marked "obsolete" by ...
2
votes
1answer
70 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
votes
2answers
214 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
vote
1answer
100 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
votes
3answers
68 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 ...
9
votes
3answers
522 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 ...
3
votes
2answers
389 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
vote
3answers
191 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
161 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 ...
3
votes
2answers
2k 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 ...
3
votes
3answers
352 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
vote
1answer
266 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, ...
1
vote
1answer
64 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 ...
3
votes
2answers
199 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 ...