Questions tagged [diy]

Questions dealing with handmade (Do It Yourself) radios and radio accessories.

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3
votes
1answer
624 views

Kenwood TM-241A direct discriminator out

I am going to do a simple SIMPLEX all-star node, using the URIx USB radio interface, which I just got. I have a Kenwood TM-241A transceiver. I was told the speaker out jack is not sufficient: The ...
9
votes
2answers
5k views

How can I calibrate a SWR meter?

I would like to build my own HF (1.8 - 30 MHz) SWR meter, however I'm not sure how I can calibrate the meter without an accurate power source. I'm targeting a power capacity of 150 W so I can use it ...
10
votes
2answers
4k views

What is the expected microphone input voltage level of a handheld transceiver?

Ok, so I'm looking to inject some computer generated CW into a little handheld rig by wiring direct into the mic input line. What sort of voltage is expected on this input, are we talking uV, mV or ...
-2
votes
1answer
121 views

multiband mimo ad-hoc wireless connections from different spectrums [closed]

I'd like to create a multiband MIMO ad-hoc wireless network. Can I turn on every GPS, WIFI and Bluetooth radio of a mobile device and synchronize data transfers at extreme speeds between a small, ...
5
votes
2answers
7k views

How to construct a loop antenna for receiving HF?

I have a unused hula-hoop in my garage, and I ran some stranded speaker wire around it once, and attached one side of the wire to the coax shielding, and the other to the coax core wire. Is this the ...
5
votes
2answers
1k views

Low parts count CW HF receiver?

I'd like to be able to provide my kids with the opportunity to build something a little better than a passive crystal set, but still very, very simple in terms of individual electronic parts count. ...
10
votes
1answer
1k views

How do I design a round or square coaxial transmission line to have a specific impedance?

Certain Hex Beam antennas use a coaxial center support post to send the RF to each antenna section, which is superior, in terms of maintenance, to a post with screw terminals connected by short ...
5
votes
5answers
2k views

Simple DIY AM receiver for 25/28 MHz

I'd like to build a simple AM receiver for 25 and/or 28 MHz to receive DCF77-formatted time code. It doesn't have to be extremely sensitive or selective - the local clock oscillator will keep time ...
13
votes
2answers
3k views

How does one read a ferrite datasheet?

Datasheets for ferrite materials are usually filled with incomprehensible graphs with greek letters. For example, Fair-Rite's 73 material: What's a $\mu'_s$ and a $\mu''_s$? What do these numbers ...
6
votes
3answers
263 views

What does a first-time operator need to know when looking for a DIY kit?

When I was growing up, I lived about three blocks from a Heathkit, and envied every device on the shelves. Now that I'm older, am teaching myself electronics and have a background in film and ...
9
votes
6answers
30k views

Is there a simple, DIY, antenna suitable for HF receive only?

So the antenna I'm thinking about doing might be* way too large for my property. Is there another simple, cheap, DIY antenna I could try on my receiver? I know I'm going to want to hook it up and ...
4
votes
2answers
1k views

What impedance matching do I need between my 300Ω feedline and Softrock receiver?

I will be assembling a Softrock Ensemble II HF receiver, and I know I'm going to want it on air as soon as I build it, so I'm challenging myself to build an antenna for it first. The plan is to do a ...
7
votes
2answers
3k views

RF Transceiver for walkie talkie use

I'm close to my EE. BSc finale and I'm looking to play around a little bit with the stuff I've learned. To be honest, I'm a little bit upset that after 4 years of learning communications theory, I'm ...
6
votes
2answers
674 views

1200 baud packet radio can't communicate

I'm toying with a simple 1200 baud packet radio I built. I'm attempting for it to be compatible with APRS, which uses the Bell 202 signaling, 1200Hz for mark and 2200Hz for space, which I assume map ...
8
votes
1answer
348 views

Variable phase antenna

I'm thinking about phased antenna arrays, and am wondering if it's possible to have three fixed position antennas, and vary the length of their individual feedlines to the common point through ...
6
votes
2answers
1k views

Dummy load construction and heat dissipation

I'm building my own dummy load, consisting of resistors submerged in liquid paraffin (or something similar, not 100% decided). I had some questions around heat dissipation and how I can calculate ...
8
votes
3answers
4k views

How do I extend broken coaxial cable?

I have a piece of 75 ohm coaxial cable of unknown type (outer diameter is around 7 mm) which has developed a breakage in the center conductor (which is stranded). This cable is an adapter cable which ...
7
votes
1answer
589 views

Is bending the tips of the antenna wires going to affect the effective length?

I'm looking at designs for low cost DIY yagi antennas for a fox hunt, and pondering coat hanger wire and PVC piping. I'd like them to be built by the youth who will be doing the fox hunt, but that ...
2
votes
1answer
2k views

Homebrew 20M SSB receiver design? [closed]

I'm looking for as simple as possible homebrew 20M SSB receiver design. I just want to start listening, but at the same time learn some radio fundamentals. So rather than buying a shortwave receiver ...
5
votes
3answers
4k views

What type of solder is best suited for radio and electronic use?

Many types of solder are available today, such as acid-core, silver, rosin-core and aluminum solder. What kind should I use for building antennas and radio equipment? Why? From test question: T7D08
12
votes
3answers
3k views

How can I add amplitude modulation to this transmitter?

I recently built this circuit, and could hear a nice full quieting signal on my short-wave radio with a 7.2 megahertz crystal for the 40 meter band. What is the simplest way I could Amplitude ...
9
votes
5answers
9k views

Home-brew 10 meter walkie talkies?

"When I was in high school, we had 8 hams at once. (Probably rare) 4 of us built little 10 meter walkie-talkies and had great fun using them on Field Day, hiking or around town. It was ...
6
votes
1answer
998 views

Are there easier ways to make traps than coax and plastic pipe?

I recently built an antenna for my attic inspired by http://degood.org/coaxtrap/. I found making the coax traps very time consuming and frustrating to tune. I got to thinking about 3D printers, and ...
6
votes
4answers
4k views

How to build a remote control unit that works on amateur radio frequencies?

The only remote control units I have used before was those little cheap 27Mhz puny range cheap units. I would like to build some sort of RC unit, which has a range up to 1km line of sight. I have a ...
18
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 ...
9
votes
1answer
100 views

Can two diodes be parallelled in RB to get double the capacitance?

It's a fact of life that air-gang capacitors, are increasingly more difficult to come by - having been superseded by the far more compact varactor diodes. My part of the world components such as the ...
6
votes
4answers
4k views

Can I listen to hams on a standard AM/FM broadcast receiver?

I am very much out of practice with amateur radio (like many others), so to some, this question may seem obvious. I don't have any specialised amateur radio equipment, but I do have a Sanyo AM/FM ...
13
votes
1answer
3k views

Is it a good idea to build your own radio transceiver today? [closed]

With all the advances in the field of electronics, microcontrollers, etc., is it a good option today to build my own amateur radio transceiver (or transmitter/receiver)? Why might one choose to build ...

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