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What is the best signal generator at around £250 or below?

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AceOfHearts

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Hi everyone,

Just looking into buying my first Signal Generator. I want the best one for the price. What is the best signal generator out there at something around £250 or below. Could consider something bit more expensive depending on the feature boost.

Mant thanks in advance for your suggestions. :)
 
DO you have a oscilloscope or power supply yet? I'd get those before I get the signal generator.
 
Hi, thanks for your response.

Yup I have an osciloscope and am upgrading my fixed 5V supply to a variable one together with the purchase of a signal generator.

peace.
 
You know a signal generator can't provide the same amount of current as a voltage supply right? You can't replace one with the other (especially since a signal generator can't output a DC waveform...to my knowledge, but even if it could).
 
Signal generators are usually constructed in different frequency bands for various technical and market reasons. So, you may have to be more specific about what you hope to do with one. Can you tell us what frequencies you are most likely to want?
 
dknguyen, I was not intending on replacing my DC supply with a signal generator. :)

RadioRon said:
Signal generators are usually constructed in different frequency bands for various technical and market reasons. So, you may have to be more specific about what you hope to do with one. Can you tell us what frequencies you are most likely to want?

Thanks :),

I dont have a particular project that needs a waveform at this moment, but I found that occasionally you need a signal from a signal generator here and there.

I found a 20Mhz one for a reasonable price at £210:

**broken link removed**

Anyone have any experience of this model? I tend to prefer a display, but this one goes upto 20MHz without a display at a good prce.

Regards.
 
I use this one: **broken link removed**

Not bad for the price. Advantages: continuous freq. readout and voltage, looks nice, and price, price. You can shape the sine output with duty cycle. Disadvantages: no duty cycle readout, not super stable in frequency, but the drift is fairly slow and not enough to bother what I am doing (ca. +/- 100 Hz at 72 KHz), all settings revert to default on shutdown.
 
jpanhalt said:
I use this one: **broken link removed**

Not bad for the price. Advantages: continuous freq. readout and voltage, looks nice, and price, price. You can shape the sine output with duty cycle. Disadvantages: no duty cycle readout, not super stable in frequency, but the drift is fairly slow and not enough to bother what I am doing (ca. +/- 100 Hz at 72 KHz), all settings revert to default on shutdown.

Thanks for the recommendation!

When you say 'continuous frequency', do you mean that that its not like the other types where the frequency is increased in steps with a knob, whereas on this, you can choose a precise setting?
 
AceOfHearts said:
When you say 'continuous frequency', do you mean that that its not like the other types where the frequency is increased in steps with a knob, whereas on this, you can choose a precise setting?

I meant there is a readout of the frequency, so if it drifts or you bump the knob, you know it. My previous generator didn't have that feature, and I had to check it periodically.

In fact, your second presumption is also correct. The frequency is not set digitally, as in a Wavetek synthesized generator. The freq is set with some sort of encoder with a non-stepped knob. There are 7 freq. ranges (0.2 Hz to 2 MHz). I am not sure whether it is synthesized internally or not. It may very well be.

There are certainly better generators on the market, but not at that price. I am very happy with mine. It is sold under a couple of brand names in the US. It is likely there is something identical to it available in the UK. (Made in China, of course). John
 
jpanhalt said:
I meant there is a readout of the frequency, so if it drifts or you bump the knob, you know it. My previous generator didn't have that feature, and I had to check it periodically.

In fact, your second presumption is also correct. The frequency is not set digitally, as in a Wavetek synthesized generator. The freq is set with some sort of encoder with a non-stepped knob. There are 7 freq. ranges (0.2 Hz to 2 MHz). I am not sure whether it is synthesized internally or not. It may very well be.

There are certainly better generators on the market, but not at that price. I am very happy with mine. It is sold under a couple of brand names in the US. It is likely there is something identical to it available in the UK. (Made in China, of course). John

Many thanks for your assistance jpanhalt, appreciate it.

Regards.
 
Not have a good idea of exactly what kind of signal source you require, here's an article devoted to a basic overview of different types of generators. From that, maybe you can zero in on a specific type.


Generators

"Generator", specifically "signal generator", is a very loose term in general that can apply to any item of equipment that outputs some predetermined, usually alternating current, "signal" or waveform. Except for very specialized generators, the waveform is usually repetitive\ and, variable in frequency and output voltage. Here are some typical types of generators.

Signal Generator. This is a generator designed for communications work, such as aligning radio receivers. Usually called an RF signal generator, better models (laboratory-grade) produce pure sine waves with very little distortion and few harmonics from around 10 to 50KHz to maybe 500MHz. "Service-grade" RF generators have distorted outputs rich in harmonics. Models usually can be amplitude modulated and have attenuators and variable output level controls. Some upper-end models can be frequency-modulated and others pulse-modulated. Older models were usually analog generators and new models are typically digitally-synthesized generators. Good ones aren't cheap and prohibitively-expensive when new. I suggest obtaining a used lab-grade analog instrument for the best cost vs. utility tradeoff. The Hewlett-Packard 606A and 606B are considered to be the finest examples of analog HF (high-frequency) generators with a range of 50KHz to 50MHz, built-in 120dB attenuator, built-in or external AM or pulse modulation as well as CW (continuous wave) output. The 606 has a high-purity output with very little distortion. Expect them to be available from on-line auctions for anywhere from $50 to $200 depending upon the source and condition. You can often find cherries for $50.

RF generators are usually manufactured for various ranges of frequencies: HF, VHF, UHF, SHF, EHF, etc. The most common are HF and VHF.

Function Generator. A function generator outputs several different waveforms. You can usually select from at least a sine, triangle and square waveform. In addition, some also have ramp and "pulse" waveforms available. Most are able to DC offset the waveforms so that they can be made compatible with various circuits under test, such as TTL or CMOS digital circuitry. The frequency range of function generators range from about 1 Hz to 200KHz for the cheapest to 0.001Hz to 40MHz for the most expensive. Some have built-in sweep capability and voltage-controlled frequency (VCF) input. On model even has amplitude modulation capability. These are all-around good generators for general experimentation. The sine wave output of most is not the best – OK for testing purposes but impossible to use if you're doing any distortion checks. The sine wave of a function generator usually gets even more distorted in the upper frequency ranges. Some function generators have built-in low-end frequency counters.

Pulse Generator. Pulse generators can usually vary the frequency, duty cycle, low-level voltage, high-level voltage, rise time and fall time of a pulse waveform. Rise and fall times are usually very fast, in the nanosecond and even picosecond range.

Sweep Generator. Sweep generators are specialized versions of RF signal generators and have similar specifications to them. They can automatically vary their output frequency about a center frequency or from a start frequency to a stop frequency. They are used for alignment of communications gear, especially receivers, allowing a graphical representation on an oscilloscope of the characteristics of frequency dependent amplifiers (e.g., IF amplifiers) or of filters. In addition to the normal signal generator outputs, they also have a ramp or horizontal output that is used to drive the horizontal input of an oscilloscope for the swept display. Higher-frequency units often used detector probes to display the output as a DC waveform since most oscilloscopes in the days of those units had low bandwidth. Today's oscilloscopes, some capable of gigahertz bandwidths, can operate directly without the use of the detector.

Stereo Generator. For aligning FM stereo radios, a stereo generator is needed. This generator outputs the left and right channel signals for aligning an FM receiver.

Teletype Generator. This older unit generated the Baudot signals needed to adjust Teletype systems. They could vary the output data rate for different systems. In addition to an RYRYRYRYRY output, they usually had a "fox" test message that, in Baudot, outputed the mesage "The quick brown fox jumps over the lazy dog. 0123456789"

Arbitrary Function Generator. This generator usually has the basic waveforms of a function generator. In addition, it can output a custom waveform designed for exactly what you need in your testing. Once you're at this level of generator, you'll probably be using lots of automated test and measurement equipment.

Television Test Generator. This generator outputs a test signal for testing out television systems. Be aware that you must have the generator designed for the television system in use: NTSC, PAL or SECAM. This generator will quickly find its days numbered as digital television takes over. There will be specialized HDTV generators take over where these analog generators left off. The TV test generator will output test patterns such as red, green, blue or white screens, various types of color bars, gray-scale gradient patterns, etc. Most output a composite color waveform while some will also have these waveforms available as a standard television RF channel.

Dean
 
Hi there Dean,

Just wanted to say thank you very much for the detailed and highly beneficial response. Given what you said, looks like I had been treating the terms 'signal generator' and 'function generator' synonimously. What I want is a Function Generator.

Thanks again for your very useful explenations and advice!

Regards.
 
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