Author Topic: Which signal generator for ham radio projects?  (Read 3511 times)

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Offline cio74

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Which signal generator for ham radio projects?
« on: March 17, 2012, 05:14:55 AM »
Hello,

I'm trying to decide which signal generator will be my best choice. The purpose of this aquisition is to help me testing RF filters (sweep/wobble), inject a signal into a receiver and trace it along different stages, test attenuators, generic RF ham radio homebrew projects for HF band, up to 20Mhz actually.

There are lots of products on the market, I am tempted to get a Rigol DG1022 which is cheap and I've read a couple of positive reviews, then at about the same price comes some GW Instek's and BK Precession. There is another Rigol which looks very interesting, the Rigol DG4062, althought I am doubling the price here. Of course, at a higher price I can have a Tektronix or Agilent but somehow I feel they are out of my league.

Considering my homebrew projects, which one do you believe would be a good choice?

Thanks.

Cornell

Offline DonRon

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Re: Which signal generator for ham radio projects?
« Reply #1 on: March 17, 2012, 06:00:12 AM »
Hi Cornell,

me too!

I am not sure which signal generator would be the right one for my ham radio projects.
I am owner of a miniradiosolutions minivna-pro which is a vectorial network analyzer. This unit enables you to make measurements on antennas and also to test filters and LC-circuits and and and ...
It can be used as signal generator too up to 160 MHz but the accuracy of the signal amplitude is not very well defined - but this is only relevant if u need a really well defined amplitude (I think u knew this). Relatiev measurements can be done very reliable.
Frequency accuracy and stability is really fine (it's a DDS) but the signal level is limited to about 0 dbm. So this is sometimes not enough.

Therefore I would like to buy a signal generator - at the same time I am not sure if i should buy a decent frequemcy counter first. But Rigol DG4062 has a frequency counter included - and up to 200 MHz is high enough.
For my stuff (shortwave up to 50 MHz) the DG1022 max frequency is to low - so DG4062 would be better.
Or should I buy a separate counter with better performance and wait with an extra signal generator?

But for you - have a look at the minivna pro - it is a really very very useful tool for the ham operator - and can be used as a signal generator with limitation of max signal level and accuracy of signal level. It costs about 400 Euros in Germany. But you will need a Computer because it is not a standalone measuring system.

Maybe we can share experience ... (What about quality Rigol - TTI - BK - GW Instek) ...

Cheers

Ronald

Offline DonRon

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Re: Which signal generator for ham radio projects?
« Reply #2 on: March 17, 2012, 06:08:12 AM »
BTW Cornell,

have a look at the Tektronix homepage.
There u can find an interesting document "Primer - XYZs of Signal generators"

Offline sacherjj

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Re: Which signal generator for ham radio projects?
« Reply #3 on: March 17, 2012, 06:19:34 AM »
If you are handy with a micro to make a simple interface and LCD display, I think this is a great deal.

http://midnightdesignsolutions.com/dds60/index.html

This fits the need for your oscillator for various QRP home brew transceivers (that is my use for it.)  There is also a thread for various ebay versions that are built up at $10, but these lack the amp to push the signal up to usable values for use as your radio oscillator.

My previous QRP rigs have all been rock bound.  And I think this will help change that.

Offline cio74

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Re: Which signal generator for ham radio projects?
« Reply #4 on: March 17, 2012, 06:26:57 AM »
I just read that pdf from tektronix, I think I read it sometime ago, it was familiar. I don't have experience with signal generators, Rigol is an Asian corporation and they have managed to bring a couple of good products to market. Price is resonable and I think it's good value for the money. Perhaps someone who have one of these may shade some light.

I knew about the DDS daugtherboard, I have ordered 4 of different types last week which I intend to use to build some LO or at least to experiment but I would like to rely on a professional product when it comes to measurements, therefore seeking to buy a qualified product rather than building my own.

Offline vk6zgo

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Re: Which signal generator for ham radio projects?
« Reply #5 on: March 18, 2012, 12:56:23 AM »
I would back away from all the "function generator" type devices.
They are OK for EEs & the like to use to produce complex waves & to play with digital stuff,but you need a real signal generator for radio work.

This pretty much means three things:

(1) Old & big & fairly cheap

OR

(2) Modern & worth as much as a small car

OR

(3)Atten or similar Spectrum Analysers with a Tracking Generator.
They are reasonably cheap.I've used a similar SA,but can't vouch for the Tracking Generators.

As you, like most Electronics enthusiasts,are probably quite poor,it probably ends up being (1). ;D

Brands for (1):

HP,Marconi,Boonton,Philips,maybe Heathkit--all stuff you might find at a Hamfest!

Offline Rufus

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Re: Which signal generator for ham radio projects?
« Reply #6 on: March 18, 2012, 01:26:33 AM »
(3)Atten or similar Spectrum Analysers with a Tracking Generator.
They are reasonably cheap.I've used a similar SA,but can't vouch for the Tracking Generators.

I wouldn't expect cheap TGs to be very good. They need a component at the right frequency then they can rely on the selectivity of the analyser to ignore any other crud they produce. They can also rely on calibration sweeps to compensate for amplitude inaccuracy which is probably applied to the SA measurements not the TG.

alm

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Re: Which signal generator for ham radio projects?
« Reply #7 on: March 18, 2012, 02:33:14 AM »
I would back away from all the "function generator" type devices.
They are OK for EEs & the like to use to produce complex waves & to play with digital stuff,but you need a real signal generator for radio work.
Agreed. I think it's nonsense to pay $500-$1000 for something with a fairly limited frequency range, all kinds of features you don't need for RF (how often do you need square or triangular waves?), and probably inferior performance (phase noise, amplitude flatness, performance at low power levels) to the real RF signal generators, like the HP 8640A.

Therefore I would like to buy a signal generator - at the same time I am not sure if i should buy a decent frequemcy counter first. But Rigol DG4062 has a frequency counter included - and up to 200 MHz is high enough.
For my stuff (shortwave up to 50 MHz) the DG1022 max frequency is to low - so DG4062 would be better.
Or should I buy a separate counter with better performance and wait with an extra signal generator?
You should be able to find a decent used counter for < $100, not much point in paying extra for a signal source with built-in counter. I'm not really impressed by the counter specs of the DG4062. 6 digits / second is fairly mediocre. Not sure why the picture shows 12 digits of resolution, do they show random noise or was this at a gate time of 1 day? 5ppm reference clock accuracy is not very impressive and makes all these extra digits of limited value, sounds like a standard standard crystal oscillator or crappy TCXO. It shouldn't be hard to find a used counter with better specs.

Offline wkb

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Re: Which signal generator for ham radio projects?
« Reply #8 on: March 18, 2012, 03:11:20 AM »

You should be able to find a decent used counter for < $100, not much point in paying extra for a signal source with built-in counter. I'm not really impressed by the counter specs of the DG4062. 6 digits / second is fairly mediocre. Not sure why the picture shows 12 digits of resolution, do they show random noise or was this at a gate time of 1 day? 5ppm reference clock accuracy is not very impressive and makes all these extra digits of limited value, sounds like a standard standard crystal oscillator or crappy TCXO. It shouldn't be hard to find a used counter with better specs.

And if you find yourself a used counter that allows an external reference clock you can hook it up to your friendly Rb-clock reference and you really have a "killer counter"  ;D

Offline cio74

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Re: Which signal generator for ham radio projects?
« Reply #9 on: March 18, 2012, 08:22:52 AM »
I would back away from all the "function generator" type devices.
They are OK for EEs & the like to use to produce complex waves & to play with digital stuff,but you need a real signal generator for radio work.
Agreed. I think it's nonsense to pay $500-$1000 for something with a fairly limited frequency range, all kinds of features you don't need for RF (how often do you need square or triangular waves?), and probably inferior performance (phase noise, amplitude flatness, performance at low power levels) to the real RF signal generators, like the HP 8640A.

That HP built/designed in 1973, what are my real chances to get a good working one after so many years? Can't find a proper manual, does it have sweep ability? Used price starting at $500 + p&p, I wouldn't call it cheap either.
« Last Edit: March 18, 2012, 09:00:53 AM by cio74 »

alm

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Re: Which signal generator for ham radio projects?
« Reply #10 on: March 18, 2012, 10:13:45 AM »
That HP built/designed in 1973, what are my real chances to get a good working one after so many years? Can't find a proper manual, does it have sweep ability? Used price starting at $500 + p&p, I wouldn't call it cheap either.

Plenty of equipment built (not just designed) in 1973 and earlier is still working fine, it depends on how it was treated during its life. $500 should be able to buy one in excellent condition if you're patient, don't confuse buy-it-now prices from used equipment dealers that hope to sell it one day to a desperate fool with market prices. Search the hp_agilent Yahoo! group for experiences, I believe some people have issues with cracked gears. The 8640 can do external sweep with its FM input (which means that you need to supply a ramp to this input), not internal sweep as far as I know.

For a manual see BAMA. This is not the only RF signal generator out there, just the first that came to mind. The other brands vk6go mentioned are also fine. I think that a general-purpose arbitrary waveform generator will not be particularly suited for your purpose and expensive for its bandwidth.

What is the minimum power level of the generator you're considering? You can't blast everything with 0 dBm, and switching external attenuators gets old really fast.

Offline cio74

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Re: Which signal generator for ham radio projects?
« Reply #11 on: March 19, 2012, 02:07:08 AM »
Thanks for your comments, there are a couple of things I'd like to cover with the signal generator, in summary:

- minimum output power  -121dBm
- maximum output power +10 dBm
- minimum frequency 100kHz
- maximum frequency 20/50MHz
- at least 2 channels, independent outputs at the same time
- sine output
- AM modulation
- linear sweeping

Any recommendation based on the above requirements? I don't really have a budget for it but I'd like to keep it below the price of a small car.

Thanks.

Cornell

Offline ted572

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Re: Which signal generator for ham radio projects?
« Reply #12 on: December 24, 2013, 11:19:37 PM »
Inexpensive Signal Generator ($200 - $330):

For those who do not have an RF Signal Generator you may want to consider the one that I have that covers 35MHz to 4.4GHz.  I previously didn't have a RF Generator that would go above 1.0 GHz, and I read about this unit in Electronic Design News (EDN) magazine.  I decided that it looked like it would be ideal for my purpose and ordered one.  I have found it ideal, works well, and is very inexpensive for this type of hardware.  It requires a PC (I use a Netbook, or Tablet PC) to control the RF Frequency, RF Output Level, and Scanning of RF Frequency, or RF Output Level.  The frequency tuning resolution is in 1KHz increments.  It is provided with two different applications for control of the RF Sig. Gen., and you can use either one.  I installed both and use whatever one I feel like using at the time.  I most offend use the LabView version, although the other one is more usable for very wide band frequency scanning.  A Ham radio operator can even use this unit as a low power Beacon transmitter, as it comes with a CW software module.
 
You can see the EDN Review at:  http://www.edn.com/electronics-blogs/the-emc-blog/4423710/Review--inexpensive-RF-generator
The manufacturer's Web site is:  http://www.rf-consultant.com/calibrated-signal-generator/

Note: I'm not financially or otherwise involved with this company in any way, I just wanted to share my enthusiasm for this inexpensive product with the group here.

BTW I have the Calibrated RF Signal Generator ($330).  I'm also have orderd one of the Standard Synthesizers ($200) for use as  LO for:  1.  RF down-converter to extend the upper frequency range of a Icom R-8500 receiver,  2.  Up/Down frequency extender for DSA815-TG Spectrum Analyzer for 1.5 - 3.0GHz, and 3.0 - 4.5GHz.  3. General universal freq. conversion with external Balanced Mixer.

Offline M0BSW

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