The John Welsh Collection

Introduction
Introduction

A Short History Of Radio
Earliest Times
Late 19th Early 20th Century
Early Last Century
Did Marconi really hear those Transatlantic signals?
The Tuned Spark Transmitter
The Coming of the Diode
The Triode, the start of modern electronics

Historic Electronics
Tesla Etcetera (Part 1)
Tesla Etcetera (Part 2)
Tesla Etcetera (Part 3)
Tesla Etcetera (Part 4)
The Thermionic Diode
The Triode Valve
The Klystron
The Klystron – Addendum
The Magnetron
The Magnetron Addendum

Principles
Analogies of Electricity Part 1
Analogies of Electricity Part 2
Scale: Some Numbers
A Crystal Set
The Electron
Wire Baluns (Part 1)
Wire Baluns (Part 2
Transmitter Impedance
The ‘Q’ of a Tuned Circuit
The Phase Locked Loop
The dbs
Units Of Measurement
Lead Acid Batteries
The Microphone
Thoughts on the Magnetic Field in a Toroid

Componants
The Transistor
The Semiconductor Diode
Capacitors (Part 1)
Capacitors (Part 2)
Resistors
Inductors
Ferriteless Toroids
The Thyristor

Aerials
Aerial Gain
The Dipole
Low Frequency Aerials
Shortend Dipole – pt1
Shortend Dipole – pt2
Low Frequency Aerials
Off Centre Fed Aerials
Aerials for Circular Polorisation
Loading Of Aerials
Traps In Aerials
Wave Polorisation (Part 1)
Wave Polorisation (Part 2)
Aerials and their Q
Monopoles and Earth Image
Radiation From A Wire

Feeders
Aerial Feeders
Coax – Does Size Matter?
Coax Calculations
Coax Impedance – Power
Coax Impedance – Loss
Skin Effect
Standing Waves (Part 1)
Standing Waves (Part 2)
Transmission Lines

Earth
Earth Image
The Measurement Of Earth Resisitance
The Importance Of A Good Earth At Low Frequencies
Monopoles and Earth Image

Operating
Are You Getting Out? The Sniffer Box
The Evolution Of Morse Code In Radio Science
Slow Morse (Part 1)
QRSS – Noise (Part 2)
Back To QRSS – (Part 3)
Q Codes

Other
Atmospheric Attenuation
Impedance Of Free Space (Part 1)
Impedance Of Free Space (Part 2)
Impedance Of Free Space (Part 3)
Impedance Of Free Space (Part 4)

EvoHam

The latest resources at your fingertipsA new website is aiming to provide a bank of up-to-date resources for amateur radio operators.The evoham.com website is focused specifically on digital voice technologies, with guides, news, reviews, and tools covering DMR, D-Star, Yaesu Fusion, P25, NXDN, M17, FreeDV and more. The site is adding new guides, reviews, tools ... Read more

YOTA Month

YOTA Month continues this weekend with special call sign GB25YOTA. Listen out for operators from the RSGB National Radio Centre and the 2nd Marlborough Scouts. Students from Buckie High School, Wick High School and Simon Langton Boys School Radio Club will be active during the week, as well as The University of Sheffield Amateur Radio Club. Next ... Read more

145 Alive

The next in the popular 145 Alive series will take place on Saturday the 7th of February from 12pm to 3pm. The event will include the addition of 144MHz SSB stations with vertical polarisation. For more information visit the 145 Alive Facebook page.

DATA Contest – 3rd Nov

Tomorrow evening (3rd Nov’) we have the DATA contest for this final month of the Autumn series. As always we are looking for as many operators as possible to get involved and add their log to the VARC total. The door to my shack is always open to anyone who would like to try their ... Read more

Memorial Day QSO Party

The Memorial Day QSO Party is an activity providing participants with an opportunity to honour amateur radio operators who are now Silent Key. The event is being sponsored and managed by the First Class CW Operators’ Club and is open to all licensed amateurs. The event began at 0900UTC yesterday, the 1st, and ends at ... Read more

YOTA 2025

Youngsters on the Air Month takes place in December and the RSGB would love you to take part in this annual event. Special callsign GB25YOTA will be active throughout the month. Whether you are an individual, club, school, university or social group, this is a fantastic opportunity to host the callsign and get young radio ... Read more

RSGB App

Exciting news – the RSGB has today released their new mobile app! The RSGB app is the perfect way to enjoy RadCom wherever you are. Download now via the Apple App and Google Play stores. Desktop, tablet or mobile – the choice is yours. Start enjoying your new membership benefit – download the RSGB mobile app ... Read more

Oceania DX Contest

The Oceania DX CW Contest starts at 0600UTC on Saturday the 11th and ends at 0600UTC on Sunday the 12th of October. Using CW and SSB on the 160 to 10m bands, where contests are permitted, the exchange is signal report and serial number.

Churches On The Air

On Saturday the 13th, lots of amateur radio stations will be on the air to take part in the Churches and Chapels on the Air event, also known as CHOTA. The event will take place from 10am to 4pm. Although stations will be working on a variety of bands and modes, most operating will take ... Read more

Blue Ham Event

Engaging with the amateur radio community on the UK MOD 5MHz (Shared) Band. Blue Ham is back over the weekend 18-19 October 2025. RAFAC stations will be active 0800 to 1700 UTC each day. Blue Ham exercises provide a platform to further develop Cadet radio operator skill and confidence by engaging with the Amateur radio community ... Read more
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