The John Welsh Collection


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

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

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

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

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

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

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)

New Hams

We continue to help bring newcomers into amateur radio and the club. In mind at the moment A) Calum M7??? – Calum is a student; I don’t yet have his callsign but he has our congratulations. B) Ivor M7EZM (Ivor lives in St Albans and again is recently licenced and has offered to do a ... Read more

New Club Meeting Venue

We desperately need to locate a new and more central venue for our more formal meeting/presentations/club projects. Several of us have spent quite some time hunting around but get little either little response from queries, expensive quotes in large (cold?) rooms etc. It would be great if someone could step up and push this forward ... Read more

November Meeting

PREVIOUS MEETING A really big thanks to Matt G4IYT for a fascinating talk and demonstration of 3D printing with examples of amateur radio and other applications. 20 members and guests attended.

Visit to the NRC

Wednesday 8th November saw 15 enthusiastic club members vist the RSGB’s visitor centre at Bletchley Park, the home of the code breakers. The club was treated to an insightful talk about the visitors centre and some of the history of the site. After splitting into two groups we took a tour of the exhibit hall ... Read more

New Pages on This Website!

Two new pages have been added to the VARC website. 1. With many thanks to Peter G3UHN – in the operating section we now have a page giving details of how to program your radio for FM repeater operation. 2. With thanks to Bob G4PVB – we have a page dedicated to receiving the very ... Read more

SAQ Transmission

After an extended period of building maintenance, World Heritage Grimeton Radio Station has scheduled* SAQ to be on air on UN-Day, Tuesday October 24th 2023 at 17:00 CET (15:00 UTC), to send out a peace message to the whole world, using the 200kW Alexanderson alternator near Grimeton in Sweden from 1924, on 17.2 kHz CW. ... Read more

SSTV Page Added

In this ever growing website, we have now added a page dedicated to Slow Scan Television. You can find it by to to the webpage HERE!

CQ WW SSB 2023

Upcoming on the 28th of October is the 48 hour CQ WW SSB contest. We entered this one last for the first time in a long time last year and it proved to be a very good and enjoyable event. We are looking to set up and enter again this year, so if you are ... Read more

145 Alive

For anyone that might be interested, there is an activity event on 2m happening on Saturday 30th September (’23) between 1:00 and 3:00pm. This is an organised activation consisiting of a series of nets that covers most of the UK. The nets are chaired so that stations can be quickly passed around to get as ... Read more

Recent work at cabin

We had quite a turn out for the working party this past weekend (3/9/23). As a result we have moved the repeater antennas off the pump up mast and mounted them on the VARC tower. The pump up mast has been moved to one side to allow room for work to begin on the shed ... Read more
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