What Are Bad Credit Loans Guaranteed Approval?

Sometimes, you may encounter financial problems or sudden expenses. Bad credit guaranteed loans is an avenue that you can explore to overcome financial challenges. With bad credit loans, you can have quick access to cash advance loans to solve pressing financial obligations.

Guaranteed loan Approval From Direct Lenders

We connect you with over a hundred lenders in the market with a simple, secure and transparent and fast lending process.

We understand that with a bad credit score, you may be unable to access loans from conventional lending institutions.

If you have a low credit score, the lending institutions will not give you a loan because you are viewed as likely default on the loan.

Banks reject people with bad credit

Banks and other traditional lending institutions may reject people with a bad credit score. However, bad credit loans can give you a financial lifeline. You should conduct thorough research on the companies before you opt to choose to work with one.

Guaranteed Loans With Bad Credit?

However, with bad credit installment loans, you have the opportunity of getting a loan even with poor credit history. You just have to find reliable lenders who do not perform credit checks for installment loans.

Bad credit lenders offer cash loans to borrowers and they do not look at any kind of credit score. Just apply your loan online with no collateral involved.

Will My Credit Score Affect My Loan Application?

Banking and other lending institutions use credit scores to determine your trust rate in repaying loans. The figure ranges from zero to 1000.

Zero means that the individual should never be trusted with a loan and 1000 means that the person is in good credit standing and can repay his loan on time. However, the ratings should not affect if you are applying for unsecured bad credit loans.Will My Credit Score Affect My Loan Application?

Guaranteed Loans No Credit Checks?

Lenders often check the income, expenses, and the ability of the borrower to repay the loan.

If you want to apply for a payday loan with no credit check (soft check may be performed), it is vital that you read all the terms and conditions before signing any agreement documents.

How Do Poor Credit Loans Approval Guarantee Work?

Most people with low credit scores have difficulty getting a loan from banks and other conventional lending institutions.

You have to note that payday loans online are different from conventional loans because they are to be repaid quickly and can accrue huge interests within a short period.

You can begin to rebuild your credit score and trust with lending institutions by repaying the loan within the stipulated time.

Do not extend your bad credit loan

Financial experts recommend that you do not extend the loan period as interest will increase considerably and you may end up paying more than what you are expected pay.

The caps for payday loan vary from one state to another and they usually range from $100-$1000.

When is the repayment period for my bad credit loan?

Bad credit loan approval guaranteed is offered to individuals with poor credit history and they are often given on short notice.

The repayment period is two weeks or your next payday. When you repay the loan on time, you will pay a flat charge.

Extending the repayment period could lead to roll over and this will increase the amount to be repaid.

Rollover of bad credit loans occurs when the borrower defaults loan repayment on the due date. When this happens, the lender will use the loan and interest rate as a base to calculate the current short term loan. This means that as a borrower, you will pay a higher interest rate.

How to qualify for a bad credit loan?

There are a few basic requirements that you must meet to qualify for a bad credit personal loan approval. First, you must be at least 18 years old and you hold a valid passport or national identity card. You need to be above 18 years of age to borrow any types of loan including title loans, online signature loans, and payday loans.

You need to employed to get a bad credit loan

You should have proof of a recurrent payable job. The lender will assess your financial situation before deciding the amount of loan to grant you. You may not qualify for the maximum limit if you are borrowing for the first time. As time goes by, you will have the opportunity of securing higher loan amounts for future loans as you build trust and rapport with your lender.

Direct lenders for bad credit

Direct lenders are the best lenders to deal with because you do not have to give your information to a third party. You should understand that when you are dealing with a broker, you as the borrower, shoulder the brokerage fees.

Building trust is important for any loan application. The first loans approved are usually small amounts but you can build trust and may qualify for larger loan amounts in the future.

Repayment of your bad credit loan

When you take out bad credit loans, you should strive to repay them on time. This will help you build trust with the lender and your trustworthiness will increase considerably.

Payday loans from direct lenders are easy to deal with because you do not deal with intermediaries and brokerage fees and they can possibly give you bad credit loan approval guaranteed.

Choose a lending company that you can trust and one which will give you the repayment terms that work for you. Privacy and safety of your personal and financial information are also crucial aspects when choosing an instant payday loan lender.

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By Mario L. Washburn

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INTRODUCTION

The resistor is probably the most common and well-known of all electrical components. Their uses are many, they are used to drop voltage, limit current, attenuate signals, act as heaters, act as fuses, furnish electrical loads, and divide voltages.

These uses are basic, for example, the voltage divider used is used in a variety of networks to divide voltages in specified increments of the applied voltage such as for analog-to-digital converters and digital-to-analog converters. They are used as matched pairs with relative accuracy much greater than their absolute accuracy. Matching is used in building voltage dividers and Wheatstone & Kelvin Bridges with extremely precise accuracy over a wide range of temperatures. This is done by matching the absolute value and the temperature coefficient of Resistance (TCR). This accuracy is limited only by the ability to accurately measure them and their stability.

There are numerous varieties of resistors. There are Precision Wirewound., NIST Standards, Power Wirewound, Fuse Resistors, Carbon Composition, Carbon Film, Metal Film, Foil, Filament Wound, , and Power Film Resistors. Each of these resistors has a useful purpose.

Resistors have numerous characteristics which determine their accuracy when used. Each will affect the accuracy to a greater or lesser extent depending on the application. Some of these characteristics are Tolerance at DC, Temperature Coefficient of Resistance (TCR), Frequency Response, Voltage Coefficient, Noise, Stability with Time and Load, Temperature Rating, Power Rating, Physical Size, Mounting Characteristics, Thermocouple Effect, and Reliability.

I will go into further detail on the type of resistor, characteristics, and materials to manufacture them in future articles. Most of my experience has been in the design and manufacture of Bridges, Networks, Precision Wirewound, Metal Clad Power, and Power Wirewound. These will be covered in greater detail..

These articles are intended to be general in nature. I would recommend that the appropriate manufacturer be consulted for specific characteristics on the resistors that they manufacture. Each manufacturer will have a specific group of characteristics in which they excel.

RESISTOR TERMS AND ABBREVIATIONS

 Resistor Tolerance

Resistor Tolerance is expressed as the deviation from nominal value in percent and is measured at 25oC only with no appreciable load applied. It will change depending on the other conditions when in use. For example, a 100 ohm resistor with a tolerance of 10% can range in value from 90 ohms to 110 ohms and this will change as power is applied and the temperature varies.

 Temperature Coefficient of Resistance

The Temperature Coefficient of Resistance (TCR) is expressed as the change in resistance in ppm ( .0001%) with each degree of change in temperature Celsius (Co). This change is not linear with the TCR the lowest at +25oC and increasing as the temperature increases ( or decreases). It can be either a bell-shaped curve or an S-shaped curve. It is treated as being linear unless very accurate measurements are needed, then a temperature correction chart is used. Normally a resistor with a TCR of 100 ppm will change 0.1% over a 10-degree change and 1% over a 100-degree change. The expression of ppm, one part in a million is similar to percent or 1 part in 100 (or percentile)

 Frequency Response

Frequency Response is the change in resistance with changes in frequency and is more difficult to measure. Where exact values are needed, these changes can be plotted but not very accurately, and normally in db change. These measurements can be made with a Boonton RX Meter which is designed for measuring low Q circuits.

 Noise

Noise levels are measured with very specialized equipment. It is extremely difficult to measure accurately and does not affect the value of the resistor but can have a devastating effect on low signals, digital amplifiers, high gain amplifiers, and other applications sensitive to noise. The best approach is to use resistor types with low or no noise in applications that are sensitive to noise.

 Voltage Coefficient

The Voltage Coefficient is the change in resistance with applied voltage and is associated with Carbon Composition Resistors and Carbon Film Resistors. It is a function of value and the composition of the carbon mixture used in the manufacture of these resistors. This is entirely different and in addition to the effects of self-heating when power is applied.

 Thermocouple Effect

The Thermocouple Effect is due to the Thermal emf generated by the change in the temperature at the junction of two dissimilar metals. This emf is due to the materials used in the leads or in the case of Wirewound Resistors the resistive element also. This can be minimized by keeping both leads at the same temperature. The thermal emf is the result of the difference in the temperature of one lead to the other lead. One lead will cause a positive emf and the opposite lead will generate a negative emf ( or visa versa). When both leads are at the same temperature, the emf’s generated will cancel each other and the same is true where the resistive element joins the leads. Resistors with nickel leads as used in certain welded module applications will generate the highest thermal emf. The resistive element (the wire) of wire wound resistors is designed with a low thermal emf, but some of the wire used for high TCR resistors will have a much larger thermal emf.

 Stability

Stability is the change in resistance with time at a specific load, humidity level, stress, and ambient temperature. The lower the load and the closer to +25oC the resistor is maintained, the better the stability. Humidity will cause the insulation of the resistor to swell applying pressure (stress) to the resistive element causing a change. Changes in temperature alternately apply and relieve stresses on the resistive element thus causing changes in resistance. The wider the temperature changes and the more rapid these changes are, the greater the change in resistance. If severe enough, it can literally destroy the resistor. Rapidly and continuously subjecting a device to its lowest and highest operating temperatures(called a Thermocycle Test) is considered a destructive test.

 Reliability

Reliability is the degree of probability that a resistor (or any other device) will perform its desired function. There are two ways of defining Reliability. One is the Mean Time Between Failures (MTBF) and the other is the Failure Rate per 1,000 hours of operation. Both of these means of evaluating reliability must be determined with a specific group of tests and a definition of what is the end of life for a device, such as a maximum change in resistance or a catastrophic failure (short or open). Various statistical studies are used to arrive at these failure rates and large samples are tested at the maximum rated temperature with rated load for up to 10,000 hours (24 hrs per day for approximately 13 months).

 Temperature Rating

Temperature rating is the maximum allowable temperature that the resistor may be used. There are generally two temperatures for example, a resistor may be rated at full load up to +85oC derated to no load at +145oC. This means that with certain allowable changes in resistance over life, the resistor may be operated at +85oC with its rated power. It also may be operated with temperatures in excess of +85oC if the load is reduced, but in no case should the temperature exceed the design temperature of +145oC with a combination of ambient temperature and self-heating due to the applied load. A word of caution, some rated loads are at +25oC and must be derated if the ambient temperature exceeds +25oC.

 Power Rating

Power ratings are based on physical size and allowable change in resistance over life. thermal conductivity of materials, insulating and resistive materials, and ambient operating conditions. Again note that all resistors are not rated alike. The safest bet is to use the largest physical size and never use it at its maximum ratings both in temperature and power unless you are prepared to accept the maximum allowable changes in resistance in life. Another thing to note; the majority of change under those conditions will occur during the first 100 hours of operation.

It is important that all of the above characteristics be considered when selecting a particular style and tolerance for each application.

TYPES OF MOUNTING AND PHYSICAL SIZES.

 RESISTOR SIZES

Resistors are available in almost any size ranging from 0.065 inches in diameter by .125 inches long to 12 inches in Diameter to several feet high (for very high voltage resistors). They come in almost any shape that is imaginable. The most common form is cylindrical with leads coming out either end. They can be manufactured in custom shapes to fit the available space when quantities justify.

 TYPE OF MOUNTING.

Resistors can be made with almost any type of mounting. If the need arises, special mountings can be designed to fit the customer’s needs. Some of the more common means of mountings are listed below. The term “Leads” is used in the general sense as a means of connecting the resistor. They may be lugs, wire leads, pins, or any means of connecting the resistor to the circuit.

 Surface Mount

Resistors are available in a surface mounting configuration. This is generally associated with chip resistors that are mounted by solder reflow techniques. This consists of a resistive element of a flat ceramic substrate (or a cylindrical ceramic core) with a solder pad on each end. Sizes range from .163 inches in diameter to .555 inches long cylindrical to a .020 high by .031 wide by .062 long chip.

 Fuse Clip Mounting.

The fuse clip type is made such that it will mount directly into a fuse clip. Fuse resistors are sometimes made like this.

 Single Inline Packaging (SIP)

The Single Inline Package is normally associated with resistor networks consisting of several resistors in the same package. It is a rectangular flat-shaped package with several leads coming out of one surface generally a narrow, long surface.

 Dual Inline Package (DIP)

The Dual Inline Package is again normally associated with resistor networks. The main difference is that leads extend out both narrow, long surfaces and are formed to either flush mount on a PC Board or through-hole mount on a PC board.

 Flat Packs

The Flat Pack is roughly the same as Dual Inline Packaging except the leads come straight out and are not formed for surface mounting or thru-hole mounting. This is just a variation of DIP mounting.

Axial Leads – Axial Lead mounting is what most of us are familiar with using. It consists of a cylindrical (or rectangular or any shape body) with the leads extending out either end parallel to the resistor’s major axis.

 Radial Leads

Radial Lead mounting is similar to Axial Lead mounting except the lead comes out of the body perpendicular to its major axis.

 PC Mounting

PC mounting consists of both leads of the resistor coming out the same surface so that it is easier to mount a resistor (or any other device) vertically. The resistor may be rectangular or cylindrical.

 4 Terminal Mounting

Most styles will offer a 4 terminal means of mounting for low values. This is important when the leads become a significant part of the value. This establishes the point on the leads where the value in within the desired tolerance. It is fixed and prevents changes in the value due to mounting variations.

RESISTOR TYPES

 PRECISION WIREWOUND

The Precision Wirewound is a highly accurate resistor with a very low TCR and can be accurate within .005%. A temperature coefficient of resistance (TCR) of as little as 3 parts per million per degree Celsius (3ppm/oC) can be achieved. However, these components are too expensive for general use and are normally used in highly accurate DC applications. The frequency response of this type is not good. When used in an rf application all Precision Wirewound Resistors will have a low Q resonant frequency. The power handling capability is very small. These are generally used in highly accurate DC measuring equipment, and reference resistors for voltage regulators and decoding networks.

The accuracy is maintained at 25oC(degrees Celsius) and will change with temperature. The maximum value available is dependent upon physical size and is much lower than most other types of resistors. Their power rating is approximately 1/10 of a similar physical size in a carbon composition. They are rated for operation at +85oC or +125oC with a maximum operating temperature not to exceed +145oC. This means that full-rated power can be applied at +85 ( 125) oC with no degradation in performance. It may be operated above +125 (85) oC if the load is reduced. The derating is linear, rated load at +125(85) oC and no load at +145oC. Life is generally rated for 10,000 hours at rated temperature and rated load. The allowable change in resistance under these conditions is 0.10%. Extended life can be achieved if operated at lower temperatures and reduced power levels. End-of-life requirements are generally defined by the manufacturer or in some cases by user specification. Some degradation in performance can be expected. In some cases, particularly if the tolerance is very low and the TC is low, the rated power is reduced to improve resistor stability through life. Precision Resistors regardless of type, are designed for maximum accuracy and not to carry power. The materials used in these resistors are highly stable heat-treated materials that do change under extended heat and mechanical stress. The manufacturing processes are designed to remove any stresses induced during manufacture.

There is little detectable noise in this type of resistor. The stability and reliability of these resistors is very good and their accuracy can be enhanced by matching the absolute value and the temperature coefficient over their operating range to achieve very accurate voltage division.

 NIST STANDARD

The NIST (National Institute of Standards and Technology) Standard can be as accurate as .001% with roughly the same TCR as Precision Wirewound Resistors and is very stable. These are used as a standard in verifying the accuracy of resistive measuring devices. They are normally the Primary Standards of a company’s test lab.

They are returned to the NIST for measurement and their accuracy is tracked throughout the standard’s life to determine the Standard’s stability. Most companies will have two sets of standards so that they can continue to measure while one set of standards is being measured by the NIST. They will alternate returning these NIST Standards to the NIST, one set one year and the other set the next year. For extremely accurate measurements, the Standard with the longest history and the best stability will be used. If erratic readings are received from the NIST over a period of years, the Standard is retired. Also, if the reading has significantly changed since the last NIST reading, the standard is suspect and all measurements made using that standard must be checked.

Normally, a standard will take about 3 years to stabilize and becomes more stable with time unless it has had excessive power applied or has been dropped. These standards are generally stored in an oil bath at +25oC. During measurement, a thermometer is placed in a cavity in the top of the Standard, called the oil well, and the temperature is recorded for each measurement so that the exact value can be determined. That is the value at +25oC plus or minus the change in value caused by the temperature coefficient. Each standard will have a temperature correction chart for exact values. Being stored in the oil bath prevents the Standard from being stressed by changes in room temperature. These are highly precise devices and are expensive to buy and expensive to maintain, but they are the primary resistor reference for any test lab.

These resistors are furnished in a totally enclosed metal case and for values above 1 ohm, this enclosure is filled with mineral oil (another type of oil may contain additives that can cause corrosion in later life). The values below 1 ohm may be built in an enclosure that is perforated and these must be submersed in oil. If power is applied without it being submersed, the Standard will be ruined.

All NIST Type Standards are equipped with provisions for two-, three-, or four-terminal measurements. The applied power is calculated and the temperature of the Standard is monitored during the test. The lowest power level consistent with sufficient resolution to get the desired measurement is used (in the area of 0.01 watts) and any appreciable rise in temperature will dictate that the measurement should be suspended and the test set-up reviewed for ways to reduce the power level. These Standards are rated for operation at room temperature only but their other characteristics are the same as Precision Wirewound Resistors.

POWER WIREWOUND RESISTORS

Power Wirewound Resistors are used when it is necessary to handle a lot of power. They will handle more power per unit volume than any other resistor. Some of these resistors are free wound similar to heater elements. These require some form of cooling in order to handle any appreciable amount of power. Some are cooled by fans and others are immersed in various types of liquid ranging from mineral oil to high-density silicone liquids. Most are wound in some type of winding form. These winding forms vary. Some examples are ceramic tubes, ceramic rods, heavily anodized aluminum, fiberglass mandrels, etc.

To achieve the maximum power rating in the smallest package size, the core on which the windings are made must have a material with high heat conductivity. It may be Steatite, Alumina, Beryllium Oxide, or in some cases hard anodized Aluminum. Theoretically, the anodized Aluminum core has better heat conductivity than any other insulated material, with Beryllium Oxide being very close. There are specific problems with the anodized aluminum cores such as nicks in the coating, abrasion during capping, and controlling the anodized thickness. There are various shapes, oval, flat, and cylindrical, and most shapes are designed to optimize heat dissipation. The more heat that can be radiated from the resistor, the more power that can be safely applied.

There is a group of these called “Chassis Mounted Resistors”. These are generally cylindrical power resistors wound on a ceramic core molded and pressed into an aluminum heat sink usually with heat-radiating fins. These are designed to be mounted to metal plates or a chassis to further conduct heat. This results in a rating approximately 5 times or more than its normal rating.

These resistors come in a variety of accuracy and TCRs. They can be custom-made as a crossbreed between a Precision Resistor and a Power Resistor; capable of handling more power than the standard Precision Wirewound but not as accurate. Practically speaking, tolerances of 1% and temperature coefficients of 20 ppm can be achieved on all except the parts that are coated with Vitreous Enamel and low values. The curing process for Vitreous (a type of glass) requires extremely high heat and shrink applying pressure to the winding. This particular group normally will run tolerances of 10% with a TCR of 100ppm/oC. Power Resistors come in a variety of ratings. Most are rated at +25oC and derated linearly to either +275oC or +350oC. Again if the ambient temperature of operation is +275oC, no power can be applied and at +125ooC 1/2 rated power can be applied.

These power ratings are based on mounting the resistor in free air with the leads terminated at the recommended point. On axial lead components, this is 3/8 of an inch from the body. If they can be mounted closer, the resistor will run cooler or you can apply slightly more power and if mounted further out, you must reduce the power. CAUTION, if mounted directly over and in contact with a printed circuit board, the heat from the resistor can charge the board if full power is applied. I don’t know of any PC Boards that are rated at +275oC.

Other means of increasing the amount of power you can apply

• (a) bond the resistor to the chassis or other metal parts

   (b) mount vertically to get the chimney effect (this is very helpful when using those wound ceramic tubes)

   (c) terminate as close to the body as practical

   (d) submerse in oil (CAUTION some types of resistor coating, particularly silicone-based coatings will disintegrate when immersed in oil and heated). This will increase the rating as much as 5 times. or reduce the temperature rise of the resistor due to self-heating.

The small power resistor can serve a twofold purpose, that is to fulfill its purpose as a resistor and act as a heater in an enclosure. Some users have used them in crystal ovens to maintain the crystal at the desired temperature. It makes a reasonably cheap off-the-shelf heater that comes in a variety of wattages, sizes, and values.

One unique type of power resistor is the “Bathtub Boat Type”. This consists of a resistance wire wound on a fiberglass cord. This is a continuously wound strip, cut into strips of the appropriate length with leads crimped. These resistive elements are placed in a ceramic shell (boat) and a highly filled cement is used to fasten these in the boat. The filler often used in cement is a ceramic material with high heat conductivity. These are very inexpensive, no effort is made to achieve tight tolerances, and low TCRs, and the range of values is extremely limited. They are often found as surge resistors in TVs and other electronic /electrical equipment. Their main selling point is low cost. They are often sold with an enamel coating for a low-power precision wire-wound resistor that is even lower in cost.

One more item to consider, Power Wirewounds are made using alloys with melt temperatures ranging from +1200o C to +1500o C and may be operated cherry red without failure for short periods of time, however the resistance value and TCR will change significantly and the insulating material will severely degrade. The bathtub boat type can not be subjected to this type of overload, the fiberglass winding form will disintegrate.

 FUSE RESISTORS

Fuse Resistors serve a dual purpose, a resistor and a fuse. They are designed so that they will open with a large surge current. The fusing current is calculated based on the amount of energy required to melt the resistive material (the melt temperature plus the amount of energy required to vaporize the resistive material).

These resistors will normally run hotter than a normal precision or power resistor so that a momentary surge will bring the resistive element up to fusing temperature. Some designs create a hot spot inside the resistor to assist in this fusing. Calculations are made and samples are produced to verify the calculations. The major unknown is the heat transfer of the materials, which can be quite significant for pulse of long duration, and is very difficult to calculate.

Mounting of these devices is critical because it will affect the fusing current. These are quite often made to mount in fuse clips for more accurate fusing characteristics.

 CARBON COMPOSITION

Carbon composition resistors were once the most common resistors on the market. They still have a very large market and prices are highly competitive. They are made from carbon rods cut in the appropriate length then molded with leads attached. The mix of the carbon can be varied to change the resistivity for the desired values.

High values are much more readily available. Very low values are more difficult to achieve. A 5% tolerance is available. This is usually done by measuring and selecting values. Normal tolerances without measurement and selection is in the area of 20%.

The temperature coefficient of resistance is in the range of 1000 ppm/oC and is negative, that is when the temperature goes up the resistance goes down, and when the temperature goes down, the resistance goes up. This is due to the carbon particles being relaxed (with an increase in temperature) and being compressed (with the reduction in temperature).

These resistors also have a voltage coefficient. That is the resistance will change with applied voltage, the greater the voltage, the greater the change. In addition to a power rating, they also have a voltage rating. (The wire-wound voltage rating is determined by the value and the wattage rating). The voltage rating of Carbon Composition Resistors is determined by physical size as well as the value and wattage rating.

One more item to consider is that due to their construction, they generate noise and this noise level varies with value and physical size. The power capability in relation to physical size is greater than Precision Wirewounds but less than Power Wirewounds.

 CARBON FILM RESISTORS

Carbon Film Resistors have many of the same characteristics as carbon composition resistors. The material is similar therefore they have noise, and a voltage coefficient, the TCR can be much lower because the formula can be varied to achieve this, and the tolerance is much tighter due to the difference in manufacturing processes.

The Carbon Film Resistor is made by coating ceramic rods with a mixture of carbon materials. This material is applied to these rods in a variety of means, the ones most familiar to me are dipping, rolling, printing, or spraying the rods in the appropriate solution. The thickness of the coating can be determined by the viscosity of the solution. This as well as the material composition will determine the ohms/square. Some of you may not be familiar with this term. It simply means that if a material has a resistivity of 100 ohms/square, one square inch with have the same resistance as 1 square mm, or 1 square foot or 1 square yard or 1 square mile all equaling 100 ohms but the power handling capability is proportional to the size.

One batch of material can produce resistors in a wide range of values. These rods are cut to the length required for a specific size of the resistor. These rods can then be spiral cut to a wide range of values. The original method of spiraling these was done with grinding wheels on a machine similar to a lathe. I am sure that later processes use lasers that are programmed to cut to specific values. The maximum ohmic value of this group is the highest in the discrete resistor group.

A tolerance of 1% can be achieved without measuring and selecting. Tolerance of less than 1% can be achieved by measuring and selecting. You should use caution in getting tight tolerances in this type because the temperature coefficient, voltage coefficient, and stability may mean that it is only good for that tolerance at the time it was installed. The TCR of carbon film resistors is in the neighborhood of 100 to 200 ppm and is generally negative. Measuring and selecting can yield even tighter TCRs.

The frequency response of this type of resistor is among the best, far better than Wirewounds, and much better than carbon composition. The wire wound resistors are inductive at lower frequencies and values and somewhat capacitive at higher frequencies regardless of value. Also, wire wound resistors will have a resonant frequency. Carbon Composition Resistors will be predominately capacitive.

 METAL FILM RESISTORS

Metal Film resistors are the best compromise of all resistors. They are not as accurate have a higher temperature coefficient of resistance and are not as stable as Precision Wirewounds. They are more accurate, do not have a voltage coefficient, and have a lower temperature coefficient than Carbon Film. TCRs of 50 to 100 ppm can be achieved.

They have a very low noise level when properly manufactured. In fact, some of the screening processes measure the noise level to determine if there are problems in a particular batch of resistors.

Metal film resistors are manufactured by an evaporation/deposition process. That is the base metal is vaporized in a vacuum and deposited on a ceramic rod or wafer. Several attempts have been made to vaporize low TCR materials and deposit on these substrates, but to my knowledge, these attempts have not been successful. This is partially due to the different boiling points of the various base metals in these alloys (I use the word alloy not entirely accurately, for these materials are not true alloys but amalgamations — they do not bond to form a molecule as does a true alloy). The very low TCR resistive materials are heat treated to achieve the resistivity and low TCR. This is not compatible with an evaporation process.

The frequency characteristics of this type are excellent and better than Carbon Films. The one area where carbon films exceed metal films is the maximum values. Carbon films can achieve higher maximum values than any other group.

 FOIL RESISTORS

Foil resistors are similar in characteristics to metal films. Their main advantages are better stability than metal films and lower TCRs. They have excellent frequency response, low TCR, good stability, and are very accurate. They are manufactured by rolling the same wire materials as used in precision wire wound resistors to make thin strips of foil. This foil is then bonded to a ceramic substrate and etched to produce the value required. They can be trimmed further by abrasive processes, chemical machining, or heat treating to achieve the desired tolerance. Their main disadvantage is the maximum value is less than Metal Film Resistors.

The accuracy is about the same as metal film resistors, the TCR and stability approaches Precision Wirewounds but somewhat less because the rolling process and the packaging process produce stresses in the foil. The resistive materials used in Precision Wirewound Resistors is very sensitive to stresses which result in instability and higher TCRs. Any stresses on this material will result in a change in the resistance value and TCR, the greater the stress, the larger the change. This type can be used as a strain gauge, with strain being measured as a change in the resistance. When used as a strain gauge, the foil is bonded to a flexible substrate that can be mounted on a part where the stress is to be measured.

 FILAMENT RESISTORS

The Filament Resistors are similar to the Bathtub Boat Resistor except they are not packaged in a ceramic shell (boat). The individual resistive element with the leads already crimped is coated with an insulating material, generally a high-temperature varnish. These are used in applications where tolerance, TCR, and stability are not important but the cost is the governing consideration. The cost of this type is slightly higher that the carbon composition and the electrical characteristics are better.

 POWER FILM RESISTORS

Power film resistors are similar in manufacture to their respective metal film or carbon film resistors. They are manufactured and rated as power resistors, with the power rating being the most important characteristic. Power Film Resistors are available in higher maximum values than the Power Wirewound Resistors and have a very good frequency response. They are generally used in applications requiring good frequency response and/or higher maximum values. Generally for power applications, the tolerance is wider, the temperature rating is changed so that under full load resistor will not exceed the maximum design temperature, and the physical sizes are larger, and in some cases, the core may be made from a higher heat conductive material and other means to help radiate heat.

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By Mario L. Washburn

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Experiment with Yagi designs on your computer!

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There are many software packages on the internet useful in designing various types of antennas. I’ve been playing with a software package named “YagiCad 4.1” since about 1992. I first installed a copy of it on our TEARA webpage back in late 1994. Since then, I’ve received many emails from users of this software who praised it’s performance and simplicity. Here, many years later, I find myself updating this website with ‘work-arounds’ and tips, as the user base continues to grow. Seems the software’s author has developed quite a following!

Yagicad 4.1 was written by Paul McMahon VK3DIP. It’s shareware, so you can download it (and lots of antenna profiles) below. It’s a DOS program and can be run outside of windows if you like. It requires a minimum of a 386 PC platform to run and a math co-processor really speeds things up, but isn’t required. The program runs best in DOS (‘real DOS, not the fake stuff rolled up inside of WIN95/WIN98/NT, hehehe) or when executed from WIN3.x, but there are simple ‘work-arounds’ for 95/98/NT users. As computers and operating system have become more complex, users have come up with methods of keeping Yagicad4.1 running. Despite a little bug with newer operating systems, I LOVE this program and have designed/built many antennas with it. I’ve used a lot of other programs, but find myself back using VK3DIP’s YagiCad 4.1.

Hey, this is a great reason to drag out one of those older PC’s you’ve had packed away, trying to figure out a ‘real use’ for it! I used to toss everything that wouldn’t run on my newer computers, but have since discovered there were MANY great programs that were somewhat simpler to use and developed for the older PC platforms. Don’t automatically discount software just because it won’t run well on your newest machines or operating systems. Anyway, c’mon and lets get started with YagiCad 4.1!

Download YagiCad 4.1 here. This file will download as yagi.zip. Once the download is complete, unzip the file into an empty directory. To start the program, type yagi41 from the dos prompt (first, switch to the yagicad’s working directory) or double click on yagi41.exe from your file manager in windows. First, before trying to start and run this program, read the rest of the notes and tips below.

NOTES FOR WIN95/98/NT USERS:

1- Keep the .yag file names exactly 7 characters long (not counting the extension). Example: 1234567.yag or WB4IUY1.yag , etc. Since I didn’t write the source code for this program, I can’t explain why it grumbles over files names of other lengths. When running on older systems with Win3.1 or just DOS6.22 (or lower), you can name the files in any length you like, but WIN95/98/NT etc only allows file names of 7 characters long to be opened. Windows NT is especially finicky about this. Since you may wish to send me your files to add to this page, share with others, or maybe run Yagicad on a newer operating system in the future, I’d recommend always naming them 7 characters long. Simple fix. Also, if you download a file somewhere with a name of a different length, simply rename it to something 7 characters long, and you’re set. Easy!

2- When you design or modify antenna designs, you’ll want to give them a unique name (so you’ll know what they are!). Never use more than 60 characters (spaces included) in the NAME/TITLE or COMMENTS sections. No problem, another easy work-around.

3- NEVER us a COMMA (,) in the NAME/TITLE or COMMENTS sections. It’ll keep your work from opening later, and sometimes crash the program. Yet another easy work-around.

4- When used with WIN95/WIN98, Yagicad will only display/open the first antenna file (.yag files) it finds, when they reside in the same directory as the program. It doesn’t do this when running under DOS or 3.1 and earlier systems, and works OK on Windows NT…go figure, heheheheeh. If that should ever happen to you, I recommend you make a directory named ‘yagicad’, and a subdirectory called ‘template’. Once you unzip the file contents into the ‘yagicad’, move all of the .yag files into the ‘template’ subdirectory. Only move the file you’re going to model from or look at into the ‘yagicad’ directory. In nearly EVERY instance of a user having problems with WinNT, Fix #1 above solved it.

I’ve not found any other oddities when running Yagicad on newer computers with WIN95/98/NT. Should any of you run across other glitches, or come up with a better ‘fixes’, please drop me a note to [email protected].

USING THE PROGRAM:
The program has all the help files contained within, and can answer most questions. It will allow you to design a basic antenna based on a NBS antenna standard, and then scale it to your desired frequency. You can then modify element diamaters, boom length, match type, element spacing and lengths, etc. You can also generate E and H plane radiation plots. All data can be sent to a local printer. You can save your designs once complete.

Yagicad 4.1 comes with a host of sample antenna designs, thus allowing you to use a working design and simply scale it to your operating frequency. You can add or subtract elements, compensate for different element diameters, conductive or non-conductive booms, etc. A word of warning, however… When you open a sample antenna, click on “create” and name the antenna session to your own unique file name BEFORE you make changes (scale it, etc). Otherwise, your sample antennas will be forever modified. Remember, when you name a file, use 7 characters as outlined in Note #1 of ‘NOTES FOR WIN95/98/NT USERS’ above.

Once you’ve designed/modified your antenna, go to “calculate”, select “auto”, and then select “resonate”. Set a residual reactance of 0.0 ohms. This step of the program will alter the driven element to be resonant at your target frequency. If the Actual “Z” (impedance) is not approximately 50 ohms, go to “edit” and move the location of the driven element back and forth on the boom a little and then resonate the driven element again. Continue this process until the actual Z is about 50 ohms.

You can add files that you and others design to your library for future reference. You can also store the designs of commercially manufactured antennas in your library and scale to other bands later. Below is a list of the supplied antenna designs (to replace yours when you forget tip #1 above, hehehe), and a few others I’ve added. If you scale or design any antennas of your own, send me a copy of the .yag file and I’ll include them here for others to play with.

The following files are available from this page in 2 formats. The first is the .yag file in text format. You can copy the text from the page, paste it to a text reader like notepad, and save it as whatever.yag. Then move that file into your yagicad 4.1 program directory. You can also read the .yag file from here. The first info in the file is the title and description. The first number is the forward gain in db. The second number is the front-to-back ratio. The 3rd number is the actual impedance of the antenna. The 4th number is the reactance. The 5th number is the # of elements. The columns are: element length, distance from the end of the boom, and element diameter. All measurements are in meters.

Following the .yag file is the same file in a zip format that can be downloaded and unzipped directly into your .yag storage directory (may be ‘template’ if you’re running yagicad4.1 on WIN95/98/NT, or the main Yagicad4.1 working directory if you’re running it in DOS or Win3.x or lower).

chchg10.yag chchg10.zip 10 element optimized yagi by Chen and Cheng. 13 db fwd with 11.59 f/b

chchg6e.yag chchg6e.zip 6 element optimized yagi by Chen and Cheng. 12.35 db fwd with 17.42 f/b

DL6WU20.yag DL6WU20.zip 22 element long yagi by DL6WU. 15.98 db fwd with 21.66 f/b

foxant1.yag foxant1.zip Simple 2 meter narrowband “sniffer” antenna. 7.45 db fwd with 47.33 f/b

foxant2.yag foxant2.zip Simple 2 meter wideband “sniffer” antenna. 6.93 db fwd with 23.77 f/b

lawson3.yag lawson3.zip One of Lawsons 3 element yagi designs. 7.45 db fwd with 47.33 f/b

lawson4.yag lawson4.zip One of Lawsons 4 element yagi designs. 8.61 db fwd with 19.27 f/b

law4new.yag law4new.zip One of Lawsons newer 4 element yagi designs. 10.53 db fwd with 35.92 f/b

lawson5.yag lawson5.zip One of Lawsons 5 element yagi designs. 10.17 db fwd with 27.99 f/b

lawson6.yag lawson6.zip One of Lawsons 6 element yagi designs. 10.45 db fwd with 27.68 f/b

nbs3ele.yag nbs3ele.zip A NBS 3 element yagi designs. 9.09 db fwd with 12.89 f/b

nbs5ele.yag nbs5ele.zip A NBS 5 element yagi designs. 10.32 db fwd with 22.43 f/b

nbs6ele.yag nbs6ele.zip A NBS 6 element yagi designs. 11.22 db fwd with 15.15 f/b

nbs12el.yag nbs12el.zip A NBS 12 element yagi designs. 13.09 db fwd with 17.99 f/b

nbs15el.yag nbs15el.zip A NBS 15 element yagi designs. 14.44 db fwd with 15.05 f/b

nbs17el.yag nbs17el.zip A NBS 17 element yagi designs. 14.18 db fwd with 18.10 f/b

iuy2m-6.yag iuy2m-6.zip A 6 element modified VK3DIP 2 meter yagi design by WB4IUY. Designed with a gap in the right place for the mast mount. 11.41 db fwd with 17.99 f/b

wb2hol3.yag wb2hol3.zip A 3 element 2 meter ‘sniffer yagi design by WB2HOL for Fox hunting. Designed for easy transport during foxhunting, and a great front-to-back raito. 7.3 dbd fwd with > 50 dbf/b !! Visit WB2HOL’s Website for a full write up on this cool antenna!

22011el.yag 22011el.zip This is an 11 element 220 yagi I (WB4IUY) designed for KG4D. It was designed around materials from an old 2 meter Cushcraft 11 element yagi.

432atv8.yag 432atv8.zip This is a 8 element ATV yagi for 432 mhz scaled from a 144 mhz Rutland yagi and optimized by KD2BD for ATV use. Constructed on a PVC boom. Very wide banded and excellant for 70 cm ATV use.

900-6el.yag 900-6el.zip This is a 6 element ATV yagi for 900 mhz that I (WB4IUY) designed on a 0.32m PVC boom. 10.47db fwd with 17.52db f/b.

900-10e.yag 900-10e.zip This is a 10 element ATV yagi for 900 mhz that I (WB4IUY) designed on a 1.05m PVC boom. 12.73db fwd with 11.44db f/b.

900-24e.yag 900-24e.zip This is a 24 element ATV yagi for 900 mhz that I (WB4IUY) designed on a 1.5m PVC boom. 14.55db fwd with 16.09db f/b.

900vhfc.yag 900vhfc.zip This is a 24 element ATV yagi for 900 mhz designed by DL6WU on a 2.5m PVC boom. 15.54db fwd with 20.92db f/b.

Visit WB2HOL’s Website for a full write up on this cool DF antenna built from a metal Tape Measure! Optimized on YagiCad.

Visit VK3VT Fox hunt beam from an article by Lawson in Ham Radio Magazine.

Other antenna design programs can be found on the TEARA software page.

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By Mario L. Washburn

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Email Reflectors available by topic…

WAIT!! If you came to this page directly from a search engine or link, you’re missing out on hundreds of pages of amateur related info on our site. CLICK HERE, or click the floating TEARA link on the page, to move to the top of our site. From there, you can select ‘HAM News’, and return to this page, complete with all of our site navigation tools. Enjoy your visit with TEARA!

Mail lists are really nice, and you only need email access to get them. What they actually are, is a mail reflector. Everyone sends their mail to the same adress, and the reflector sends it to all subscribers. Similar to the way repeaters work for VHF/UHF RF.

I’ll give you the list of reflectors, and you can subscribe to those that have topics of interest to you. The subscription is via an automated service, so it’s pretty simple. With most, you send a message to an adress, and only have a simple statement in the body of the message like:

SUBSCRIBE [listname] [your email adress]
Don’t forget to turn ‘off’ any signature lines that might be automatic in your email program. That’s it. OK?? Well, here goes…

For the Yaesu reflector…
mail to: [email protected]
In the body of the note type only: subscribe
For the Drake reflector…
mail to: [email protected]
In the body of the note type only: subscribe drake

Ham Equipment reflector at UCSD…
mail to: [email protected]
In the body of the note type: add ham-equip

For the Ham-Tech group…
mail to: [email protected]
In the body of the note type: subscribe ham-tech

For the Qrp group…
mail to: [email protected]
In the body of the note type: subscribe qrp-l
Once subscribed, send all messages to: [email protected]

For the KnightLite list…
(This is an excellant QRP group)
mail to: [email protected]
In the body of the note type only: subscribe

The Fast Scan ATV reflector…
mail to: [email protected]
In the body of the note type: add ham-atv

For the HATS (Houston Amateur TV) group…
mail to: [email protected]
In the body of the note type: subscribe hats

For the ATV mail server…
mail to: [email protected]
Include in the body of the type the following line: SUBSCRIBE ATV

A reflector about SSTV…
mail to: [email protected]
In the body of the note type: add ham-slowscan

VE7TCP DX reflector…(great list!)
mail to: [email protected]
In the body of the note type: subscribe

DX reflector at UCSD…
mail to: [email protected]
In the body of the note type: add ham-dx

Another DX reflector at UCSD…
mail to: [email protected]
In the body of the note type: add ham-dxing

For the Cq-contest group…(mail to both)
mail to: [email protected]
ALSO mail to: [email protected]
In the body of the note type: subscribe cq-contest

For the Topband (160 meter) group…
mail to: [email protected]
In the body of the note type: subscribe topband
Once subscribed, send all messages to: [email protected]

A reflector about HF operation at UCSD…
mail to: [email protected]
In the body of the note type: add ham-hf

For the BOATANCHOR group…(vintage radio)
mail to: [email protected]
In the body of the note type: subscribe boatanchors
This is a pay reflector (costs $12/yr) and is worth every penny in my opinion if you like vintage stuff. You can subscribe for free for a month or two to see if you like it first.

Another Boatanchors reflector at UCSD…
mail to: [email protected]
In the body of the note type: add ham-boatanchors

The Hallicrafters reflector…(Hallicrafters collectors)
mail to: [email protected]
In the body of the note type: subscribe

The Old Time Rig reflector… (Vintage rig collecting and restoring)
mail to: [email protected]
In the body of the note type: subscribe otrig
Once subscribed, post all mail to: [email protected]

The A.M. reflector…
mail to: [email protected]
In the body of the note type: add ham-am

To get on the VSS (vintage solid state gear) list…
mail to: [email protected]
In the body of the message type: SUBSCRIBE vss

For the glowbugs group…(homebrew with tubes)
mail to: [email protected]
In the body of the note type: subscribe glowbugs

A reflector about home-brewing equipment…
mail to: [email protected]
In the body of the note type: add ham-homebrew

To get on the Microwave reflector…
mail to: [email protected]
In the body of the message type: ADD ham-uwave

To get on the VHF weak signal list…
mail to: [email protected]
In the body of the message type: SUBSCRIBE VHF

EME reflector at UCSD…
mail to: [email protected]
In the body of the note type: add ham-eme

VHF-UHF reflector at UCSD…
mail to: [email protected]
In the body of the note type: add ham-vhf-uhf

6 meter reflector…
mail to: [email protected]
In the body of the note type: subscribe six
Once subscribed, all mail should be sent to: [email protected]

To get on the ARRL bulletin reflector…
mail to: [email protected]
In the body of the message type: SUBSCRIBE

To get on the Dayton hamvention list…
This list doesn’t run year-round, so just keep trying to subscribe every few weeks until it works…
mail to: [email protected]
In the body of the message type: SUBSCRIBE Dayton-l

To access QRZ via email…
send a message to: [email protected]
leave subject line blank

in the body of the message type:
lookup callsign
lookup callsign
lookup callsign
lookup callsign

Do that for as many calls as you need to lookup. That’s it!

Example:
(in the header)to: [email protected]
(in the body of the message)
lookup n4nto
lookup wb4iuy
lookup ke4tzo
lookup k9mx

Another callsign good database accessable via email. This one is mostly for DX qsl’s…
send a message to: [email protected]
leave subject line blank

in the body of the message type:
callsign
callsign
callsign
callsign

Do that for as many calls as you need to lookup.

Example:
(in the header)to: [email protected]
(in the body of the message)
n4nto
wb4iuy
ke4tzo
k9mx

To get on the w4atc (NCSU) reflector…
mail to: [email protected]
In the body of the message type: subscribe w4atc

To get on the BitBucket reflector…
(BitBucket is a mailing list (reflector) devoted to specialized amateur radio communication techniques.
-RTTY, Packet, Pactor, GTOR, Clover
-ATV, FAX, APT, DSP
-R/C, Telemetry, Balloons, Rockets, Robotics
-homebrew, modifications, interfacing, widgets, etc
mail to: [email protected]
In the body of the message type: SUBSCRIBE bitbucket
To get on the Land Mobile reflector (commercial 2-way)…
mail to: [email protected]
In the body of the message type: SUBSCRIBE

The Amtor reflector…
mail to: [email protected]
In the body of the note type: add ham-amtor

Amateur Digital reflector at UCSD…
mail to: [email protected]
In the body of the note type: add ham-digital

A reflector about packet radio…
mail to: [email protected]
In the body of the note type: add ham-packet

A reflector about Spread Spectrum…
mail to: [email protected]
In the body of the note type: add ham-spread

A reflector for Exotic modes of operation at UCSD…
mail to: [email protected]
In the body of the note type: add ham-exotic-modes

A reflector about FM operation at UCSD…
mail to: [email protected]
In the body of the note type: add ham-fm

A reflector about RTTY…
mail to: [email protected]
In the body of the note type: add ham-rtty

The Antenna reflector…
mail to: [email protected]
In the body of the note type: add ham-ant

A reflector about modifications to equipment…
mail to: [email protected]
In the body of the note type: add ham-mods

The Tower reflector…
mail to: [email protected]
In the body of the note type: subscribe towertalk

I may be off on the syntax a tad on one or two of these (it’s been a while since I subscribed to some of them) but the list processor will mail you back with the correct subscription info if so. Have fun!!

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By Mario L. Washburn

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Links to info about building radio equipment and accessories…
WAIT!! If you came to this page directly from a search engine or link, you’re missing out on hundreds of pages of amateur related info on our site. CLICK HERE, or click the floating TEARA link on the page, to move to the top of our site. From there, you can select ‘TEARA’s Links’, and return to this page, complete with all of our site navigation tools. Enjoy your visit with TEARA!

AIM Electronics
All Electronics Corp
AllTronics
American Milspec
Antique Electronic Supply Online!
Byers Chassis Kits
Cable Experts
Chip Directory!!!
Circuit Works Custom PC board fabrication
Cirrus Logic
Coax – Davis RF
Component Forums at EIO. These are Wonderful, check them out!!
Consolidated Electronics Inc
Dan’s Small Parts
Digi-Key Corporation Home Page
EIO, a HUGE electronics surplus outlet in Redondo Beach, CA!
Electronics USA Unique Ham Radio products, electronic kits, and cool gadgets.
Exar Analog Devices
Fair Radio
Far Circuits Supplier of kits and parts
Greenstone USA Manufacturer/Distributor of Vacuum Tubes for all applications
Greg’s page Nice photos and loads of links
Harry’s Homebrew Homepages
HAMMOND MFG. CO. Enclosures, Transformers & Power Bars
Hitachi
HMC Electronics
Homebrew Radio Gear-K9GDT
HW-7 Mods Better rx for the HW-7!
John’s page Well done page about John’s homebrew station and more
Kanga USA QRP kits and parts.
Intersil
MCM Electronics
Motorola
Mouser Electronics
National Semiconductors
Newark Electronics
NTE Electronics
Ocean State Electronics
Pacific Semiconductors
Parts Express
PennState Component Database page
QRP Homebuilder’s Page Loads of great projects!
Radio Shack
RASON Projects Page Many projects for the shack from N1HFX
RF Connection Specialist in RF Connectors and Coax
RF Parts
Transmission Line Calculator
Value Surplus
Wireman Coax, connectors, antenna wire, etc…
Do you know of any additional Homebrew websites that I could add to this page? Are any of the links you tried on this site broken?? If so, please drop me an email by clicking –>HERE<–, or email to [email protected]

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By Mario L. Washburn

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