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)

Volunteer for WRTC

The RSGB is delighted to announce that it is an official partner for this year’s World Radiosport Team Championship, also known as WRTC. RSGB representatives will attend the event which is being held from the 8th to the 13th of July 2026 at Wyboston Lakes in Bedfordshire. They’ll meet radio amateurs and spectators from around ... Read more

IRTS Contest

On Wednesday the 18th of March, the Irish Radio Transmitting Society 80m Evening Counties Contest runs from 2000 to 2100UTC. This is not the usual 80m contest that we operate in (that’s the Club Championship contest) but is a new one to the schedule. Using CW and SSB on the 80m band, the exchange is ... Read more

145 Alive

Our radio club VARC will be operating as a net controller from the cabin on the 18th April from 12:00 to 3pm taking VR offline while we do. Let’s operate the club call and get on the air. Any volunteers for a shift? Can always take turns helping each other log. Get in touch via ... Read more

British Science Week

British Science Week 2026 began last Friday and a wide variety of amateur radio activity is taking place throughout the ten days. From kit building, to Morse-a-thons, from skeds to radio direction finding, this is a fantastic showcase of amateur radio to wider audiences. There is still time to get involved in this national event ... Read more

Straight Key Month

The Straight Key Century Club’s Straight Key Month is currently underway. The annual on-air event commemorates the Club’s founding in 2006 and celebrates the original instruments of early radiotelegraphy including straight keys, bugs and ‘cootie’ keys. Listen out for the K3Y callsign which is being aired from the ten USA call areas. Information on the ... Read more

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
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