Summary of AM shortwave transmitter
Summary: The article presents an educational 8-watt AM shortwave transmitter project (QRPAM) with warnings about legal operation and use of a dummy load. It lists tube choices for oscillator and power amplifier, required HT power supply (300 V at 300 mA), and notes parts are available from surplus suppliers or salvage; ready-built units may be obtainable via Station QRP.
Parts used in the 8 Watt QRPAM Shortwave Transmitter:
- 6BX6 (EF80) oscillator tube
- 6CJ6 or 6DR6 (EL81) power amplifier tube
- High-tension (HT) power supply capable of 300 volts at 300 mA
- Dummy load (for safe operation)
- General chassis, wiring, and tube sockets
- Components salvaged from old radio communication sets or surplus suppliers
IMPORTANT: The published circuit diagrams of Station QRP are for educational purposes only. These are offered for the furtherance of the readers’ knowledge regarding Radio Frequency design and principles. At all times during operation an assembled unit must be connected to a dummy load.
In most countries law prohibits the unlicensed operation of transmitters w hen connected to an antenna or even to have such equipment present in a fully or partially installed state. All responsibilities for the ultimate use of the diagrams are bornesolely by the builder and/or operator
8 Watt QRPAM Shortwave Transmitter Are you interested in building this 8 WattAM shortwave transmitter?
Most parts used in this transmitterare still available (e.g. Surplus Sales of Nebraska http://www.surplussales.com)o
r can be salvaged from old radio communicationsets. If you wish to purchasea ready-builtonec ontact me viawww.stationqrp.com for details. QRPAM Shortwave Transmitter Technical Data Transmitter: Tube(UK=Valve)
-Oscillator 6BX6 (UK = EF80) -Power Amplifier 6CJ6 or 6DR6 (UK=EL81) HT Power Supply:300 Voltsat300 mA
For more detail: AM shortwave transmitter
- What is the output power of the QRPAM shortwave transmitter?
The transmitter produces 8 watts AM output. - Which tube is used for the oscillator?
The oscillator uses a 6BX6 tube, equivalent to EF80 in the UK. - Which tubes can be used for the power amplifier?
The power amplifier uses either a 6CJ6 or a 6DR6 tube, equivalent to EL81 in the UK. - What is the required HT power supply specification?
The HT power supply must provide 300 volts at 300 mA. - Are parts for the transmitter still available?
Most parts are still available from surplus suppliers or can be salvaged from old radio communication sets. - Can I buy a ready-built transmitter?
The author offers ready-built units; contact via www.stationqrp.com for details. - Do I need to use a dummy load?
Yes; at all times during operation an assembled unit must be connected to a dummy load. - Is unlicensed operation allowed with an antenna?
In most countries unlicensed operation when connected to an antenna is prohibited; responsibility lies with the builder/operator.
