Category: Technical

74HCT240 transmitter

I’m working on a new QRP transmitter based on the 74HCT240 octal buffer, the circuit has been described on many places, even in ARRLs books. Read the Original Article

An fm transceiver from an unexpected chip

The Si47xx series of integrated circuits from Silicon Labs is a fascinating series of consumer broadcast radio products, chips that apply SDR technologies to deliver a range of functions that were once significantly more complex, with minimal external components and RF design trickery

How to make a mains filter for EMC and noise reduction

Technical Reference/Filters Article showing how I’ve made a mains filter to reduce EMC in the electricity supplying my shack. I’ve used a type 31 Fair-Rite ferrite core and the video shows how this performs on 160m through to 40m. [su_button url=””]Full Original Article[/su_button]


A recent article on the popular Hack-a-day website showed readers how to build a very simple ADS-B ‘Cantenna’ to use with their SDR USB dongle radio [su_button url=””]Full Original Article[/su_button]

How to program Ailunce HD1 to contact the repeater quickly without PC

Almost all the operations can be done via radio keypad. Dual Band DMR Radio,Analog and Digital Combined. Compatible with Motorola Tier Ⅰ&Ⅱ How to program a rf DMR repeater on HD1. How to program FM repeater very quickly [su_button url=””]Full Original Article[/su_button]

LM723 Problems

I am having problems with the Bias Regulator circuit on my TS-930S PA Board, that is driving me nuts ! It uses an LM723. I thought I would start a new thread here, in case people who can advise haven’t seen my other thread. I have described the ongoing problems here: Hope somebody can…

DIY CobWebb Antenna

Antennas/CobWebb A DIY guide to build your own compact multiband HF antenna based on the G3TXQ version using a 1:4 balun. This article includes the full part list and instructions to assembly, including the center plate. [su_button url=””]Original Article[/su_button]


‘SELECTIVE FADING’; I am told is essentially, “A Radio propagation anomally caused by partial cancellation of a Radio signal by itself. – the signal arriving at the receiver by two different paths and at least one of the paths is changing(lengthening or shortening)”. A few decades ago, 1960 era, as a child, I remember the…

Nice homebrew AM TX in qst

Interesting circuit, I like the mic preamp with tone controls and a bright/normal switch. I may build it and experiment, 12AX7 and a handfull of parts for the preamp. Heising modulated… [su_button url=””]Original Article[/su_button]


Software/Software Defined Radio QRadioLink is a Linux analog/digital SDR transceiver application with Codec2 digital voice mode support. [su_button url=””]Original Article [/su_button]

The C-Pole Antenna

Antennas/Vertical C-Poles for 20m and 6m, it is a folded half-wave dipole with an asymmetrical tapped 50-Ohm-point in the lower part of the antenna. Design hints by DK7ZB [su_button url=””]Original Article[/su_button]

7 Element Yagi Calculator

Antennas/Antenna Calculators Online javascript antenna calculator designed to give the critical information of a particular beam antenna, in this case a seven element Yagi, for the frequency chosen. [su_button url=””]Original Article[/su_button]

Tower Wind Speed Measurement Height

I was curious for those of you that have a tower mounted anemometer, how high did you put it? Seems like there is a standard out there for weather reporting of 33ft. Do any of you measure at both 33ft and at the top? -Sean KB0VER [su_button url=””]Original Article[/su_button]

How to Solder Properly : Mr. Carlson’s Lab (video)

IF you intend to Repair or Restore … you need Solder skills and proper tools. Bad Soldering introduces “new problems” … which prolongs successful repairs into restorations. How to Solder Properly by Paul Carlson, VE7ZWZ Mr. Carlson’s Lab – YouTube channel [su_button url=””]Original Article[/su_button]

The 40/30 Pyramid

Antennas/Delta loop A dual band delta loop antenna resonating on 30 and 40 meters band using a single wire for the top slopers on both 30 and 40 meters and does not need any balun For the full article, [su_button url=””]Original Article[/su_button]

Quick antenna length calculator

Antennas/Antenna Calculators An excel spreadsheet that in a really simple way checks how much to trim your antenna elements. Download the xls file and watch the presentation video include in this page For the full article, [su_button url=””]Original Article[/su_button]