Beverage design 160 mtrs Bi Directional

Two times Bi-directional beverage’s design and construction

For our 160mtrs contest operation we had the opportunity to set up two 1 to 2 wavelength beverages. This articles describes the design criteria, components used and the final electrical and mechanical construction.

 

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Athena Contest Statistics and Goals

Athena now compatible with n1mmlogger+ 

Athena is the goddess of wisdom, peace, warfare, strategy, handicrafts and reason, shrewd companion of heroes and the goddess of heroic endeavour

The goddess Athena was a superb strategist and many of the Greek myths recount tales of her help given to various gods, goddesses, and heroes as they went into battle or faced seemingly impossible tests. Although she was widely known in one of her roles as "Athena Goddess of War", it was as a mediator and a planner that she excelled. She always worked to prevent war, but once war had been joined the goddess Athena fought efficiently for her side.

In this constellation Athena will be used as a graphical interface to display N1mmLogger compatible real time contests statistics including goal data. Athena can help you with the best strategy and do welll in e.g. the CQ "Worldwide War"contest....

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Thucydides - History file manager

Thucydides was an Athenian general and historian. He is known for his History of the Peloponnesian War, the struggle between Athens and Sparta (431-404 B.C). His emphasis on accuracy and his impartial attitude in reporting events and drawing conclusions won him the title "father of scientific history". Thucydides believed that studying events of the past could help men understand similar events in the future and perhaps avoid similar mistakes. He saw and reported the greed of power as the underlying cause of this war. Thucydides included facts he knew to be true, either from his own experience of the war or from interviews with persons who had participated in other actions.
In this constellation Thucydides will be used as a manager for history files used by n1mmlogger.

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RF Tube model

RF Tube modeller is an aid to perform poweramplifier design in a more efficient way. Based on the by manufacturer supplied graphical data (constant current graphs) a number of key parameters can be calculated for different operating conditions. 

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Filament Inrush Protection

Filament inrush protection is required for most tubes. Upon applying AC (or DC) power to the cold filament this inrush current is limitted by the source resistance and cold filament resistance. In case of AC operation this source resistance is mostly the secundairy transformer resistance in series with, if applicable a series resistor (serie resistor to set the filament voltage for correct filament voltage under steady state operation). Cold filament resistance will be a fraction of the "hot" filament resistance as calculated from the datasheet (filament voltage divided by filament current).

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GS35B 2mtrs Poweramplifier

Goal was to have for contest operation a stable and virtual no tune amplifier capable of delivering 1KW of output power. This goal has during 2003 been accomplished, based on the design of DL4MEA. This design is using a Russian GS35B tube. At some points this design has been altered and those will be described below in more detail.

  • Measurement of the kathode and grid current
  • Anode lecher lines changed to single tubes and seperate (doorknob) anode capacitors
  • Added is a novel controlcircuit for fault monitoring and TX-RX sequence

GS23B 70cm PA

For EME and contest operation the need arose to get on the 70cm band power levels around 1 KW. Design and construction should be such that no major de-tuning exists over a contest timeframe and more or less unattended operation is possible. These design criteria where possible by using a GS23B tetrode tube in a cavity design.

Read more: GS23B 70cm PA

160mtrs antenna selection box

For 160mtrs contest operation a multitude of receive and transmit antennaes needed to be controlled and selected. Some of the antenaes will be powered by a seperate poweramplifier. For ease of operation a remote control was needed for quick selection of one of the receive antennaes.

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2mtrs active 4 way splitter

Driving more than one poweramplifier can be done by using a simple passive power splitter arrangement. Drawback of this approach is that you do not have fine grain control on the driving power for each power amplifier. In most cases you need different driving power because the poweramplifiers are not equal. One PA might be a tetrode tube amplifier, needing only 20W of input power to get full output level and the other might be a triode of bipolar PA needing substantial more driving power. One way to overcome this is to use different sets of attenuators (a.o. fixed resistive attenuators, different lengths of coax cable, etc). End result is a time consuming and not satisfactory and optimal operation.

This active splitter design preclude all those drawbacks !. A description is given for a 4 port 144MHz design, but also a 2 port and a 3 port 432 MHz design have been constructed.

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70cm Active 3 way splitter

Driving more than one poweramplifier can be done by using a simple passive power splitter arrangement. Drawback of this approach is that you do not have fine grain control on the driving power for each power amplifier. In most cases you need different driving power because the poweramplifiers are not equal. One PA might be a tetrode tube amplifier, needing only 20W of input power to get full output level and the other might be a triode of bipolar PA needing substantial more driving power. One way to overcome this is to use different sets of attenuators (a.o. fixed resistive attenuators, different lengths of coax cable, etc). End result is a time consuming and not satisfactory/optimal operation.

This active splitter design preclude all those drawbacks !. A description is given for a 3 port 432MHz design, but also 2-and a 4 port  144MHz designs have been constructed.

Read more: 70cm Active 3 way splitter

Noise Gain Analyzer

Under construction

TS711/811 PTT modification

When using the TS711/811 in CW mode the break-in behavior can't be switched off, i.e. as soon as the KEY-line/input is active (ground) the radio will go into transmit and RF power is generated. Normally when using an external poweramplifier or preamplifier some sort of sequencer/timing device is used which will control the sequence when going from transmit to receive and vice versa.

Read more: TS711/811 PTT modification

ATF54143 LNA Max. RF input

Introduction

During (contest) operation we used for the 70cm band some pre-amplifiers based on the design of oz1pif (OZ1PIF, 2009). As an active element this design uses a Agilent ATF-54143 Low Noise Enhancement Mode Pseudomorphic HEMT. Pre-amplifiers were mounted near the antenna and switched by means of some RF coaxrelais. Although performance is very good a number of HEMT's where destroyed during transceive operation. After ruling out any mall configuration in receive-transmit sequencing the only cause of destruction could be the RF power at the input due to the finite isolation of the coaxrelais. This paper investigates the permissible RF power level at the input of the pre-amplifier and as such provides some metrics to the required isolation level.

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TX/RX sequencer V1

Proper changing from receive to transmit operation is vital for the receive pre-amplifiers as well as the used coax relays. Especially it becomes important with 1 Kilowatt power levels, mistakes will almost certain mean the immediate death of the pre-amplifier! To prevent including sequence control circuitry in every amplifier a standalone sequencer was built.

Read more: TX/RX sequencer V1

TX/RX sequencer V2

Proper changing from receive to transmit operation is vital for the receive pre-amplifiers as well as the used coax relays. Especially it becomes important with 1 KiloWatt power levels, mistakes will almost certain mean the immediate death of the pre-amplifier! To prevent including sequence control circuitry in every amplifier a standalone sequencer was built.

pcb_assembled_300_298

Read more: TX/RX sequencer V2

Dummyload watercooled

During the design and construction of my 160 mtrs power amplifier the need arose to have a well defined 50 Ohm load. This article describes the construction of such a 50 Ohm load capable of sinking 4 kW with 100% duty cycle for very long period of time. Constructed is water-cooled load consisting of 18 times 250 Watt high power flange mount resistors. 

dummyload resistors
dummyload side

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RF Pulser Controller

To align a power amplifiers for optimum CW (pulse) operation this pulse controller was developed. Also it can be used when a dummyload with non adequate powerhandling is availabe (average powerhandling requirement is reduced by a factor of 2 to 3). It will control the exciter (transceiver), obtain a forward power voltage sample and output this voltage for measurement with a DC voltmeter. Input is a footswitch for continues pulse operation or a paddle/pushbutton for single shot measurement. Pulse parameters (duration, sample delay time and duty cycle) are controlled by an single chip microcontroller.

peakdetector breadboard 250 213

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Web Enabled Contest Experience

Article: web enabled contest experience



Under construction

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