50 ohm dummy load design software

Figure 2 shows the impedance of the motherload with the reactive circuit engaged and bypassed two 8 ohm sections in parallel. The code for the dummy load is available as part of the download and is also printed in the assembly manual. The design goals of big dummy are a little grander. The photo attached is of a dummy load currently on the market, and i am inquiring what it is they use to dissipate the load. Dummy loads are offered with impedance values of 50 ohm, 75 ohm or 93 ohm. It is common to see multiple resistors in parallel to obtain higher power dissipation for resistive elements. They work with all radios from 160 meters through 650 mh. P6150 for 50 ohm oscilloscopes for 50 ohm oscilloscopes instructions this document contains information that supports basic instrument operation. There is also a simple diode rf detector which rectifies and smooths the peak voltage, which can be read.

May 12, 2018 instead, a dummy device, known as a 50 ohm load or 50 ohm terminator, can be used. This one is conservatively designed for rigs that have power output levels up to w, such as the kenwood hybrid lineup. The mfj264 is ham radios most versatile 50 ohm dummy load. My calculations are done for the load but i have some questions about. High voltage dummy load 3000 ohms, 5400 watts there are 45 layers of 6 resistors, each one being. It is a standard arduino ide file that can be modified to suit your needs. Find great deals on ebay for rf dummy load and 50 ohm dummy load. Jul 18, 2000 p6150 for 50 ohm oscilloscopes for 50 ohm oscilloscopes instructions this document contains information that supports basic instrument operation as well as how to service to the module level.

What i wanted was a dummy load with more power handling 50 watts preferably and a way to tap off the transmitters output so i can make some measurements. Rf loads are available in female, jack, male, male to female and plug genders. The reason that the load needs to be as resistive as possible is that it needs to continue looking like a flat 50ohm load no matter what frequency is applied to it. The code samples the power input 30 times as determined by the variable named iterations by reading the a1 sensorpin analog pin. The data was almost identical to the readings from lil dummy, meaning this load is a flat 50. Pro trucker cb ham radio antenna watt 1 gallon can dummy load 50 ohm. Based on my own experiments, you can drive resistors at about ten. Figure 2 thick film resistor figure 1 compact dummy load r3 4. The four dark cylinders in the photo are undoubtedly resistors, probably 200 ohms each, assuming its a 50 ohm load. Mar 04, 2016 use plain water with a little salt added to build your own dummy load by k5lxp 100 w dummy load. This wattmeter is based up on a dummy load of 50 ohm which can handle 50w. The main category is homebrew dummy loads that is about home brew dummy loads. Dummy load for amplifier testing electronics for you.

This dummy load consists of 20 1k 1% 1w resistors connected in parallel to make a 50 ohm 20w qrp dummy load. The dl300m dummy load simulates an accurate 50 ohm antenna up to 150 mhz, enabling you to test your transmitter without radiating a signal on the air. I also want to make a cantennastyle load built into a paint bucket and filled with dielectric oil for cooling. If it is worse, check to see if you divided the ref level by the dl reading and try again. The tap off point provides a means to connect a spectrum analyser or second receiver to monitor and set up the transmitter and also the means to measure power. Rf 50 ohms dummy load pcb design high frequency ground. How to build a dummy load for testing large amplifiers. A couple gallons of silicone load oil i got when we burned up a 5 kw load at work and a 16 qt.

I have a couple of things i want to try with these boards, and the first is a 50 ohm dummy load for my handytalkie ht. A dummy load is used to check the operation of a transmitter and also can be used to check the swr meter. It is an open circuit, very bad for the finals on a transmitter. Mfj 264 dummy loads are versatile 50 ohm dummy loads. Db50wnm dummy load, 50 watt, typen male, db products clean used, 50 watts, 50 ohm, black anodized heatsink, mfr. Ideally, a 50 ohm dummy load presents a 50 ohm resistance with no reactance at all design frequencies. The design uses the aluminum case as the ground connection for one end of the resistor. Dummy loads, buy new and used products from ham radio.

I have also kept the software a minimal design to help beginners get started in programming. When building a rf qrp amplifier i required a 50 r dummy load. Buy boxaload 50 ohm rf dummy load ham radio accessories. A search on the farnell website found a bourns 50 ohm 150 watt terminator 6 mm x 9 mm x 1 mm thick at a very reasonable price.

A useful shack accessory, this is a simple 50ohm 20w dummy load kit using 20 individual 1k resistors in parallel. This may give you the idea of building your own cheap dummy load and do your tuning through this. Inside, they contain a 50 ohm resistance with very little stray inductance or capacitance. The circuit for a dummy load is stupid heh simple its literally just a 50 ohm resistor across the antenna connectors inner conductor and shield. Test your transmitter the proper waywith a dummy load from dx engineering. An essential piece of equipment in any radio shack, the boxa load is a 50 ohm dummy load. Based on my own experiments, you can drive resistors at about ten times their rating for short periods of time without cooling. If youre driving the dummy load with low power less than 200 watts then this math doesnt matter too much. My dry dummy load consists of ten globar 500 ohm resistors of either 100 or 200 watts each i forget. Pasternack 50 ohm rf load terminations are constructed of an aluminum finned heatsink, beryllium copper, nickel plated brass or stainless steel. Pro trucker cb ham radio antenna watt 1 gallon can dummy. Jul 26, 2016 a useful shack accessory, this is a simple 50 ohm 20w dummy load kit using 20 individual 1k resistors in parallel. May 20, 2014 if youre driving the dummy load with low power less than 200 watts then this math doesnt matter too much.

The simplest test on a dummy load you can perform is to measure it with an ohmmeter it should be 50. Jul 02, 2018 a simple dummy load for testing audio amplifiers. Hi i am a rookie on both rf and pcb design and i am currently trying to do a 50 ohm 11 watts dummy load project for 100mhz1ghz. I found on the web this very simple way to build a cheap homemade dummyload for hf. A dummy load, or terminator, consists of a noninductive power resistor or multiple resistors in series and parallel and a heat sink, both rated for the maximum power to be dissipated. It does it all works with all radios from 160 meters through 650 mhz and from qrp to the full 1500 watt legal limit. The boxa load includes a builtin led rf indicator to show when you are transmitting. The load resistor was made of 20 1 kohm metal film resistors with a power rating of 2 watt each. The reason that the load needs to be as resistive as possible is that it needs to continue looking like a flat 50ohm. The measurement will be displayed in watt on a 2x16 char display. This allows us to construct an average power reading.

This project will explain how i build my new wattmeter. An essential piece of equipment in any radio shack, the boxaload is a 50 ohm dummy load. A wide variety of 50ohm dummy load options are available to you, there are 774 suppliers who sells 50ohm dummy load on, mainly located in asia. Male sma terminations from fairview microwave include feedthru load and rf load versions also known as male sma loads or male sma dummy loads include standard part numbers with chain and without chain. Additionally this kit has a diodecapacitor rectifier for detecting the peak voltage of the rf waveform, which may be measured using a dvm. Pro trucker cb ham radio antenna watt 1 gallon can. If i build another then ill reduce the costs by sourcing the oil differently but even so, thats a good price for a decent hf dummy load. These 50 ohm loads or terminators look like a connector with one end sealed up.

This was a project to make a dummy load or, as the finished thing is more correctly labelled, a fifty ohm resistive load. Since the dummy load can be constructed more easily using generalpurpose pcbs, as shown in fig. All resistors were soldered together in parallel connection which leads to a total resistance of 50 ohm. The dummy load code for the nano is available on the download page. Ive now tested my homebrew dummy load using my analyser to read about the performance, please read the blog entry here.

We offer fancooled, aircooled, and oilfilled dummy loads also known as dummy antennas from the mosttrusted brands in ham radio, including ameritron, diamond, mfj enterprises, palstar, and vectronics. Dc to 150 mhzs handles shortterm rf power up to 300 watts. Instead, a dummy device, known as a 50 ohm load or 50 ohm terminator, can be used. I dont have a 50 ohm dummy load power measurements require a dummy load.

The whole point of a dummy load is to sink power from the amplifier without producing sound. You can subsitute the shown value components to handle your megawatt amplifiers. Assemble three sets of resistor banks using backtoback generalpurpose pcbs as shown in fig. Use plain water with a little salt added to build your own dummy load by k5lxp 100 w dummy load. I thought that it would be a good test case to sweep the dummy load from 1 through 54 mhz, and see how it performed as a function of frequency. The first step is the form of a round pcb with the above picture just as much as 2 pieces of 3 cm diameter, to which drilled the diameter of the. Dec 05, 2012 the photo attached is of a dummy load currently on the market, and i am inquiring what it is they use to dissipate the load. This link is listed in our web site directory since sunday sep 28 2008, and till today the 50 ohm dummy load has been followed for a total of 2753 times. Our mismatch loads allow you to select the impedance mismatch your rf testing requires. In radio a dummy antenna is connected to the output of a radio transmitter and electrically simulates an antenna, to allow the transmitter to be adjusted and tested without radiating radio waves. It is capable of making very accurate impedance measurements. About the 50 ohm dummy load the resource is currently listed in in a single category. Add slowly salt to water to reach the right proportion for 50 ohm resitance, mfj 269 hepled me to do this.

Our rf dummy load varieties are rohs and reach compliant. Feb 07, 20 i found on the web this very simple way to build a cheap homemade dummyload for hf. Heavy duty design and function rust proof powder coated inside and out. Since i didnt have one, a hunt was on to source the parts to build a dummy load. Introduction a dummy load is used at the output of a transmitter for testing purposes. Handles 100 watts for 10 minutes, 1500 watts for 10 seconds. Jfw has been designing, manufacturing, and delivering quality terminations and mismatch loads for over 30 years. The frequency ratings for these coaxial dummy loads range from dc to 50 ghz. It does not look like a bunch of resistors in parallel, but i could use some information. Otherwise, i would just use a subwoofer array as a load. A dummy load is a device used to simulate an electrical load, usually for testing purposes. Fairview male sma terminations are available in 50. Do another trial your display value for power should be very close now.