Amateur Radio Stack Exchange
Amateur Radio Stack Exchange

Questions tagged [diy]

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

157 questions
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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 several times the target frequency, but what effect…
Adam Davis
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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 represent, and how can I use them in amateur radio?…
Phil Frost - W8II
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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 Modulate this signal with a microphone or computer output…
Skyler 440
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Is it a good idea to build your own radio transceiver today?

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 over buying, or the other way around? How should…
kR105
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11
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Will electrically joined dipoles of different lengths, at right angles, behave as a multiband antenna?

I haven't seen this done, (which, after more than a century of amateur and professional radio development, is probably a bad sign), but I had an idea the other day for simplifying the setup and feed to cover more than one band without the compexity…
Zeiss Ikon
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10
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Why is my diplexer such a spectacular failure?

I'm trying to create a diplexer for the 2m and 70cm bands so that two antennas can share a feedline to my "shack". My radio is a Yaesu FT60 handheld, 5W max. I have home made a j-pole for 2m, and a neat little ground plane antenna for 70cm, both of…
user14945
10
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2 answers

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 with my HF radio. However, my test equipment at…
W5VO
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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 even Volts?
user521
10
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1 answer

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 lengths of coax used in previous designs. I'd like to…
Adam Davis
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Why do we have to hand wind toroids?

Many, if not most, ham radio kits (transceivers, tuners, ununs, baluns) require the builder to hand wind and tap their own toroids. (example) This is a considerable area of stress for newbie builders and a failure point for their builds. I can’t…
RoboKaren
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Why don't monolithic HF transceiver ICs exist?

HAM operators who build their own HF rigs typically do so using discrete components. However, for VHF and UHF rigs, an operator can make use of monolithic transceiver ICs on the market For example, there is this one for 30MHz ~ 1200MHz: AK2401…
watkipet
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9
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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 especially fun because this was pre-cellphone and…
Skyler 440
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9
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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 venerable BB212, MPN3700, MV1662 are almost…
VU2NHW
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Baofeng low power mod

I have a few baofeng UV5R handhelds sitting around that only transmit, the receiver is damaged. What I would like to do with these is build a foxhunt transmitter. Sure, I could set it to low power (1 watt) and put it through a less efficient…
Skyler 440
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Building a portable event repeater

How does one go about building a portable repeater for use at events? Preferably at low cost, and with a minimum of bulky parts (so it's travel friendly). Obviously you'd need a pair of radios to handle RX and TX, taking into account that the TX…
Trevor Johns
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