Questions tagged [diy]

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

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5
votes
3answers
515 views

RF Bridge Problem - K6BEZ Antenna Analyzer

This question regards erroneous SWR measurements of K6BEZ antenna analyzer design from 2013 using Arduino and AD9850 DDS modules. There have been many variations of it by other people over the years. ...
5
votes
0answers
53 views

How to estimate input and output impedance of an amplifier?

I'm trying to figure out how to design power amplifiers which input and output are properly matched to 50 Ohm. My thinking was that the most bullet proofed approach would be to model an amplifier in ...
3
votes
0answers
78 views

DIY Triplexer for HF (low), 6m (med), and 2m/440 (high)

I'm looking at picking up the TYT TH-9800, which is a Quad-Band FM radio on 10m/6m/2m and 440 (I'm lucky enough to have some 6m and 10m repeaters in the area). I know there exists quad band antennas ...
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 ...
4
votes
0answers
101 views

Problem with theory of HF detector

I'm currently trying to build my own SWR power Meter. This design is based on the so known HT detector with schottky diode BAS70. For my understanding, and for easy purpose, I'm currently focusing on ...
6
votes
7answers
652 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 ...
10
votes
5answers
1k views

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 ...
2
votes
1answer
69 views

Can these in-band spurs from rpitx be eliminated somehow?

I'm putting together a 2m NBFM transmitter/receiver combo using rpitx and rtl-sdr. During testing my low-pass filter I discovered that rpitx is generating spurious signals within and around the band (...
9
votes
6answers
29k 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 ...
7
votes
3answers
796 views

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 ...
0
votes
1answer
40 views

Detect multiple broadcast on same channel

I have a number of ear guards with two way radio communication. They can only be set to send and receive on the same channel, and they have the option of dividing themselves according to the ctcss ...
1
vote
1answer
39 views

PSR500/Pro106/WS1040 Phase II Upgrade?

I want to know if one can upgrade the hardware chips/ the CPU/DSP inside police scanners to do Phase II. I know they cannot do Phase II due to hardware/software limits but if whistler can upgrade ...
2
votes
2answers
70 views

coax switches for HF

Like many hams I have several radios and several antennas. instead of constantly connecting and disconnecting coax cables I would like to feed several antennas in to some type of switch so I can ...
1
vote
4answers
162 views

Indoor HF/VHF/UHF antenna, have someone an Idea?

My wife doesn't think that having tall antennas is acceptable. Does anyone have a solution for this? Our house is 16 meter long and 10 meter wide. I have an antenna tuner (if it can help).
4
votes
2answers
119 views

How to design constant impedance tracks on PCB?

I have designed PCB's in the past, but need to draw a constant 50 ohm impedance track on the project I'm planning. I know the calculations for (for example) a coplanar wave and how to get a straight ...
4
votes
3answers
4k views

Antenna tuner design

In a related question about a broadband antenna for SDR it was suggested me to build or buy an antenna tuner. Since maybe it was not clear to everybody, I'm designing an antenna tuner for reception, ...
4
votes
1answer
79 views

no contacts with Rockmite

I finished building my Rockmite ][. It's running off of 3x 18650s, or 12v. I connected it to a MFJ-1840T and held the antenna horizontally in the air (also tried vertically) with my hand. I tried ...
2
votes
0answers
98 views

Unknown kit from DK0TV

When my father - who became a ham years after I did - passed away, I found an unstarted project (board + components), which I only re-discovered again years later. The board is marked DK0TV-001, and ...
7
votes
4answers
765 views

LoRa radio transceiver for PtP mesh?

I am very new to general RF/radio in general other than basic WiFi, but I'm looking at the feasibility and cost of a long range (>200M between nodes, sometimes probably 500+M) in flat terrain, ...
5
votes
4answers
427 views

Testing for 'Bad' Coax

I have a lot of 'donated' coax that has been given to me with unknown provenance. I'm wondering what things I can do that can determine whether I keep it or send to the tip? Some of the things I have ...
0
votes
4answers
102 views

Can I make signal transmitter without decoder?

I'm sorry if my title seems weird but I just started to learn about signal transmitting and I don't know where to start I'm searching about simple ways to make diy radio but I can't really ...
1
vote
1answer
69 views

How to calculate VFO/IFO frequencies?

I am trying to build a simple superhet receiver for listening SSB signals. I read several articles about SSB and got confused so I am looking for some practical explanation. I have 2 mixers, quartz ...
0
votes
1answer
60 views

Lead in wire size [closed]

I have a copper wire antenna about 100 feet long that I have relocated and now need about 75 feet of lead in wire. What type & size of wire should I use?
3
votes
1answer
71 views

Help understanding transmission loss of trivial circuit

I was trying to DIY a VHF/UHF diplexer, and got some weird readings from the VNA. By debugging I reached this trivial circuit: Which has the following frequency response: I'm trying to figure out ...
0
votes
2answers
69 views

How should i go about building my first transceiver?

So i want to build my very own transceiver, not looking for anything worldwide, just local but i do have a background in arduino and some electrical engineering, what tutorials would you recommend?
2
votes
4answers
745 views

Amateur Radio Long Distance Data Communication

My friends and I are going off to college ~180 miles/290 kilometres apart. As a project, we are looking into creating a data communication connection between our two schools. Our requirements would be:...
2
votes
3answers
153 views

Will a “crystal set” work with an untuned RF amp stage?

In my ongoing process of building up to a homebrewed general coverage receiver/transceiver, a first step might reasonably be a crystal set, where a tuned circuit and simple, or even improvised, ...
1
vote
1answer
139 views

Design/Build a DIY Audio Attenuator and Splitter

I’m trying to be less of an appliance operator. To that end, I recently came up with a simple project that I thought I could figure out and build entirely on my own. I was wrong. My goal was to ...
2
votes
0answers
88 views

Has this regeneration control been done?

I'm planning to build a two-tube reflexed RF regen receiver soon. I'm examining methods of controlling the regeneration — it needs to be possible to both initiate and halt oscillation in all bands (I ...
1
vote
1answer
49 views

Can the transmit and receive functions of a boat anchor transceiver share the tank circuit?

I'm starting design work on a two-tube (two-valve, for those who prefer that term) reflex-regen receiver that I hope will cover AM broadcast through 160m-10m -- both amateur bands and those "in ...
3
votes
3answers
379 views

Why have knife switch storm grounds for antennas vanished?

Long ago, it was fairly standard to provide lightning protection for outdoor radio antennas by installing a large double-throw knife switch -- antenna leads to the center, radio on one side, ground on ...
1
vote
0answers
57 views

Microwave kiln for glass [closed]

I am building a 1000W microwave kiln for glass jewelry. The internal capacity needs to be around 5 litres. What internal dimensions of the cavity should I avoid, or strive for, to ensure even heating....
1
vote
3answers
2k views

Slot antenna for 2 meter mobile

My primary vehicle is a Smart car, with a roof that's a piece of plastic(100% moon roof). Not the most awesome of cars to use for grounds. I'm building a bumper mounted antenna tower, EMT with some ...
2
votes
1answer
194 views

Frequency Display for Old Tube Radio

I have a Hallicrafters S-120 1960s vintage vacuum tube receiver (an "All American Five" superhet with solid state rectifier replacing one of the "five" tubes). It works well, doesn't have excessive ...
5
votes
1answer
1k views

What is homebrew?

My question is the title itself: what is homebrew (or home brewing)? And how do homebrews differ from ordinary ham radios?
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 ...
1
vote
2answers
80 views

Will close-loop metal hangers affect antenna radiation?

I'm working on a kite-supported antenna for an 80m QRP rig -- to be flown at beaches, on mountaintops, and possibly other places where I want to work HF but don't want to lug poles or give up ...
5
votes
4answers
701 views

Are QRP transceivers only meant for CW communication?

I was just thinking about making a QRP transceiver, but are they only used for CW (Morse code) communication? If it is so, can I modify a QRP for two way audio communication?
1
vote
2answers
556 views

How to convert a crystal controlled tranceiver to VFO (aka Unbinding from the Rock)?

If you look at the circuit diagram for a Colpitts crystal oscillator, it's pretty simple -- a crystal, load resistor, and capacitive voltage divider, with the positive supply feeding the control ...
2
votes
4answers
829 views

What is a simple kind of amateur radio transceiver I could try to build, as a beginner?

I am new to amateur radio, and I'm trying to learn the basics of the hobby. I would like to build a simple radio transceiver from scratch (i.e. not from a kit). I have searched the Internet for ...
4
votes
1answer
198 views

What dielectric strength is required for a variable capacitors in a 100W T-network antenna tuner?

I would like to build a 100W T-network antenna tuner: I have a 12-pole wafer switch, 12.5 meters of enameled copper wire (d=1.5mm) and a pair of 12-365pF variable capacitors rated 200V DC (dielectric ...
4
votes
1answer
178 views

Will I get cleaner keying by keying the oscillator, or interrupting the amplifier B+?

One of my goals as a new ham is to homebrew my own transmitter (using vacuum tubes, aka valves). Initially I'll stick with CW for the transmitter, though over time I might build an AM modulator or ...
5
votes
3answers
3k 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
4
votes
2answers
106 views

How do homebuilders find an audience to distribute kits to?

Many (QRP) homebuilders offer their projects as kits. A popular series nowadays is the BITX. There are often mailing lists connected to those projects; I am a member of several. I'm wondering how ...
7
votes
2answers
210 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 ...
3
votes
1answer
667 views

Air Coil AM & Shortwave Crystal Radio Using 1/4" Copper Tubing

Looking to build a crystal radio, need help with the coil. I'm looking to get something to work with 1/4" thin wall copper tubing. Already have some nice diodes and whatever capacitors/resistors I ...
5
votes
3answers
325 views

How can I determine/measure power rating of a DIY air capacitor?

I've build an air capacitor like the one described in this article, although I used 1 mm thick single side copper boards (FR4) instead of solid copper sheets. I would like to use such capacitors in my ...
9
votes
2answers
552 views

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 ...
4
votes
3answers
3k views

Recommended 9:1 unun core type(s)

I would like to construct a 9:1 unun that connects my QRP transceiver to a random-wire antenna. The transceiver's antenna connection is an unbalanced BNC jack and the random-wire antenna is, well, a ...
1
vote
5answers
394 views

Are cold temperatures harmful for ham radio equipment?

I'm getting ready to build an HF / CW kit and just finished setting up a workbench in my garage. While I was wrapping up, I started wondering if the cold temperatures this winter might be harmful to ...