Amplifiers

Welcome to my Amplifier Page.

My passion is building things.

A selection of tubes, modern and ancient - large and small.

Centre Back - 4CX5000A

Left to Right - 3-500Z, 8877/3CX1500A, 4CX250B, 807, 813

Centre Front - 2C39A

I RECEIVE A LOT OF EMAILS ASKING QUESTIONS ABOUT THESE PAGES.

HIGH RF FIELDS ARE POTENTIALLY VERY DANGEROUS AND CAN CAUSE PHYSICAL INJURY. TUBE AMPLIFIERS WILL INVARIABLY CONTAIN LETHAL VOLTAGES AND PHYSICAL CONTACT WITH A HIGH VOLTAGE SOURCE WILL RESULT IN INSTANT DEATH.

NONE OF THE AMPLIFIERS DESCRIBED ON THESE PAGES ARE SUITABLE FOR BEGINNERS, AND MOST ARE ONLY SUITABLE FOR CONSTRUCTORS WITH CONSIDERABLE EXPERIENCE.

I AM WILLING TO TRY AND ANSWER QUERIES BUT I DO REQUEST THAT YOU EITHER INCLUDE YOUR CALLSIGN OR LET ME KNOW WHY YOU WANT TO BUILD AN AMPLIFIER. I AM VERY RELUCTANT TO ANSWER EMAILS UNLESS I HAVE CONFIDENCE THAT THE POTENTIAL BUILDER IS AWARE OF THE POTENTIAL HAZARDS AND WILL EXERCISE APPROPRIATE SAFETY PRECAUTIONS.

One of the problems facing most amateur constructors nowadays is obtaining suitable components. Fortunately there are two notable but very diverse exceptions for which it is still relatively easy for the Amateur to obtain components - QRP rigs and QRO amplifiers.

I very much enjoy doing metalwork so amplifiers are a natural for me. My interest in amplifiers dates from some dealing with a particular model of a professional solid state linear - the manufacturer shall remain nameless. For some ridiculous cost, the amplifier simply used a number of push-pull modules built around common mobile radio bipolar PA devices really intended for HF Land Mobile service. These modules when combined were to give the claimed 1kW output. The "thing" took almost a couple of hundred amps from a simple capacitor output power supply, the unstabilised +12V supply rail was bouncing up and down like nothing on earth, dipping as low as 8/9 volts on peaks. The "thing" could never have performed to the claimed manufacturer's specification, and I knew I could construct something better.

The following pages give photos of some of my past and present projects,

1200 Watt Solid State Amplifier for 160 thru 6 metres.

300 Watt Solid State Amplifier for 6, 4 and 2 metres.

A Ring of 6 x 2C39A for 23cms (a AN/UPX-4 unit).

A Pair of 4CX250Bs for 2 metres

An Experimental 3 kW Class D Amplifier for 136kHz

A 2.5kW "Decca Clone" Class D Amplifier for 136kHz

A single 2C39A amplifier using Spring Collet tube connectors

An Add-On 8170 Amplifier for QRP rigs

An Easy Build, Legal Limit, Ultra-Linear Amplifier for 50 MHz.

18 Watt Amplifier for 23cms using Mitsubishi Modules.

An 8170 amplifier for 2 metres