Questions tagged [electronics]

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

Filter by
Sorted by
Tagged with
5
votes
3answers
3k 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 ...
1
vote
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
114 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 ...
9
votes
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
vote
2answers
257 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
votes
1answer
191 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
521 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
vote
0answers
42 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
vote
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
73 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
156 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 ...
7
votes
2answers
513 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
vote
0answers
52 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
239 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?
5
votes
2answers
186 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
votes
1answer
84 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
votes
1answer
1k 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
vote
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);...
2
votes
4answers
2k views

Why doesn't adding a resistor inline to a 12 V car charger change output voltage

I purchased a baofeng car charger for my little UV5Rv2 HT. It was advertised to work with the radio, so I didn't think much of it. It turns out, all it does is pass my car electrical system voltage ...
5
votes
2answers
838 views

Adapting an antenna coupler

I've built AA5TB's antenna coupler: I left out C2 because I didn't understand why I would need it - why would I? It works fine without. Unfortunately, when I started tuning for a 5W 20m transceiver, ...
5
votes
2answers
115 views

Stacked shell inductor — what's its function/use?

I have a device of copper and iron (about 8 kg) which looks like two shell inductors joined so that there is some coupling but high leakage. The windings seem to be identical. Each is a single ...
3
votes
1answer
182 views

Would a switched RF attenuator be (a)symmetric?

I picked up this 0-80 dB switched RF attenuator at a flea market, with no part number or other useful markings other than the knob settings. I've tested it and confirmed that it works, but there's one ...
5
votes
1answer
229 views

Are there an MTTF/MTBF/MTTR data on the typical tubes used in the FT-101/TS-520?

I browse ebay.com for used rigs in good condition and approaching my shoe-string and ... There appear to be a decent quantity of boat anchors out there - FT-101, TS-520, TR-4 to name just a few. By ...
10
votes
1answer
2k views

How does a switching mixer multiply the two signals?

I understand what a mixer does, and when I see it in a block diagram it's obvious what purpose it serves and how it fits in the overall design of the radio. However, when I look at the schematics and ...
5
votes
1answer
564 views

Do vacuum variable capacitors have higher Q than air variable capacitors?

Do vacuum variable capacitors have higher Q than air variable capacitors? They are not commonly seen in tuners or crystal sets. But they are mentioned as superior to air variables for resonating ...
17
votes
3answers
4k views

SDR sampling bandwidth - do the bits per sample matter?

I'm looking at data converter chips for a homebrew SDR design, and I see that I can choose not just the sampling frequency, but also the bits per sample. Obviously the sampling frequency has to be ...