I want to make a VHF radio - Page 1
Forum section: electronics / rf-microwave

author: MAD MACRO
author_rank: Regular Contributor
timestamp: June 18, 2016, 07:28:30 am
content: not sure if this is the right place to post this..as the title says, I want to make a VHF radio, transmitter and receiver. I build 2 of those and I have myself a walkie-talkieI have pic18F2550, is it good for the job ?Do you recommend a certain schematic to follow ?what is the hardest step in doing this project ?any advice would be helpful.

author: German_EE
author_rank: Super Contributor
timestamp: June 18, 2016, 07:44:43 am
content: A PIC is a digital device and to make a VHF transceiver will require lots of analog electronics working at over 50 MHz, this is not an easy task. For starters you could look at some of the simpler kits which will come with a pre-made PCB and a full set of instructions.One more thing. To operate a radio transmitter normally requires a licence issued by the state.

author: MAD MACRO
author_rank: Regular Contributor
timestamp: June 18, 2016, 08:00:32 am
content: QuoteI think you're right, i'm a location where these pre-made PCB are not available and to order them online would cost me a fortune.I can learn fast, I know it's not an easy task.can you please help ?QuoteI have a licence. it says "it's a third world country, do what you want"

author: Rerouter
author_rank: Super Contributor
timestamp: June 18, 2016, 08:11:32 am
content: Its more that the licensing scheme teaches you everything and more to make and operate transmitters,The schematics for a CB radio are floating widely on the internet, e.g. try searching for "DIY Walkie Talkie" some using only a handful of components to get something that works, but may be spewing noise everywhere, to closer to 30-50 components to get something that you could make a 2 way transceiver out of while not acting as a local RF jammer.

author: MAD MACRO
author_rank: Regular Contributor
timestamp: June 18, 2016, 08:26:37 am
content: Quote from: Rerouter on June 18, 2016, 08:11:32 amgoogled these things, got nothing serious, nothing reliable.I need a personal recommendation for a certain schematic to follow, please.I don't want to make wrong steps and waste my time.

author: PA0PBZ
author_rank: Super Contributor
timestamp: June 18, 2016, 08:43:44 am
content: If it is about the communication part there's no way you can build anything cheaper than buying it online:http://www.ebay.com/itm/PMR-FRS-GMRS-Walkie-Talkies-T628-8-22CH-2-Way-Radios-121-Privacy-Codes-Orange-/272116064549That is why there are not a lot of modern schematics for building something like this.If it is about experimenting with VHF just start by getting some test equipment and start by building an oscillator, then try to modulate it, then a receiver and so on.

author: MAD MACRO
author_rank: Regular Contributor
timestamp: June 18, 2016, 09:04:52 am
content: Quote from: PA0PBZ on June 18, 2016, 08:43:44 amwow, I never knew i can buy things on ebay. thanks man.Quote from: PA0PBZ on June 18, 2016, 08:43:44 amcan you be a bit more specific/technical ?

author: nugglix
author_rank: Regular Contributor
timestamp: June 18, 2016, 09:44:50 am
content: Ahh... troll time...

author: MAD MACRO
author_rank: Regular Contributor
timestamp: June 18, 2016, 10:31:22 am
content: Quote from: nugglix on June 18, 2016, 09:44:50 am

author: zl2wrw
author_rank: Regular Contributor
timestamp: June 26, 2016, 07:09:34 am
content: Hi Mad Macro,If you just want a cheap radio, I suggest that you just buy a suitable radio transceiver. I know nothing about the laws in Egypt, do you have a CB or "licence free" band that anyone is allowed to use?On the other hand, if you want to learn about radio, I strongly suggest that you make contact with a local amateur radio club, get yourself an amateur radio licence, which, the law of Egypt permitting, will allow you make your own radios and transmit on various amateur bands which range from VLF to mm-wave, and with transmit power levels that are far above of what is permitted for CB or licence-free users.To get your amateur radio licence, you will have to sit and pass an exam on electronics and radio theory (and possibly morse code), but the other club members will help you study for the exam.Some radio amateurs build their own transceivers "dead bug" or "Manhattan" style, without a proper PCB - for example:https://g3xbm-qrp.blogspot.co.nz/2009/06/sixbox-qrp-6m-am-rig-closer-to.html

author: vk3yedotcom
author_rank: Frequent Contributor
timestamp: July 27, 2016, 11:00:22 am
content: Recently I've been messing around with cheap 433 MHz UHF data modules.The transmitters can be made to transmit AM or FM voice (depending on how they're adjusted - with mine the DC bias to the data input pin was critcal).The superregenerative receivers can receive data and AM voice.My most recent video shows them talking to one another(older videos are mainly transmitter tests to a good FM receiver - got over 1km range)

author: whalphen
author_rank: Regular Contributor
timestamp: August 03, 2016, 09:33:40 pm
content: I recently spent a lot of time searching for VHF radio designs and schematics. I wanted to build a low power VHF transmitter and also a transceiver for use on high altitude balloons. I found mostly old schematics using many adjustable inductors and variable capacitors. I wanted something simpler. I ended up building a transceiver using the Si4464 ISM chip. It can be used for digital communications, but not voice. There are other modules available which provide VHF transceiver capabilities. They need to have supporting circuitry added. I came to the conclusion that there is little need for home built VHF radios anymore because commercial VHF ham radios can be bought really cheap now.