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 https://forums.qrz.com/index.php?threads/74hct240-transmitter.614973/

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=”https://www.dxzone.com/dx32977/how-to-make-a-mains-filter-for-emc-and-noise-reduction.html”]Full Original Article[/su_button]

Recyclo-Cantenna

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=”http://www.southgatearc.org/news/2018/february/recyclo-cantenna.htm”]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=”https://forums.qrz.com/index.php?threads/how-to-program-ailunce-hd1-to-contact-the-repeater-quickly-without-pc.596695/”]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: https://forums.qrz.com/index.php?threads/ongoing-kenwood-ts930s-pa-problem.592358/ 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=”https://www.dxzone.com/dx32938/diy-cobwebb-antenna.html”]Original Article[/su_button]

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=”http://www.southgatearc.org/news/2017/december/sporadic-e-openings-on-50-mhz.htm”]Original Article[/su_button]