Re: Cool cheap oscilloscope for troubleshooting

David Wilcox

Has anyone information on how to use the Digilent analog scope?  The reference manual reads like a college text book on its features but using it for ham radio testing for a newbie I need a simple book  with lots of pictures..... ha!

David J. Wilcox K8WPE’s iPad

On Jul 31, 2019, at 11:36 PM, Jerry Gaffke via Groups.Io <jgaffke@...> wrote:

For those starting out, I'd start with a cheap DVM (ideally one that measures
capacitance too) and perhaps one of those JYE oscilloscopes.
Build some audio amps up from transistors, look at how they work with the scope.
Calibrate it by looking at a the 5v square wave coming out of the si5351 on the Raduino
(the si5351 can be made to go down to 4khz, or you could use a Nano counter/timer).
Write code to set that square wave to any frequency you want, and perhaps sweep through a range
of frequencies.  .Scale that square wave amplitude using resistors and verify the result on the scope.
Try building some of your own test gear, perhaps a diode RF probe for the DVM, and a step attenuator.
Use the Raduino as a signal source to evaluate the response of a filter or amplifier.
All of the above could be done for around $100, including the $59 cost of a Bitx40 and the $20 JYE scope.

Farhan is probably right, something like the Antuino is perhaps more useful than a scope
for radio work.  Though I'd find it hard to get by without a scope of some sort.
The scope helps us visualize what is really going on.

For those not starting out, you probably already know if it's worth kilobucks to you
for high end scopes and spectrum analyzers and binocular inspection microscopes
and vector network analyzers and signal generators and frequency counters and
rubidium standards and current limiting power supplies and desoldering stations
and a building out back to put it in.

Jerry, KE7ER

On Wed, Jul 31, 2019 at 11:51 AM, Doug Hall wrote:
Jack's point is well made. I'm all for saving money, but of all the places to cut corners test equipment is not one of them. The biggest flaw in the $25-$50 'scopes is not their lack of features or low bandwidth, it is their lack of measurement accuracy. And when you think about it, measurement accuracy is the reason we buy test equipment in the first place. 

You can buy a new Rigol DS1102E for $300. That's a dual channel 1 gigasample per second, 100 MHz bandwidth 'scope with two decent X10 probes and a host of features such as FFT (use it as a spectrum analyzer), PC connectivity, USB, on-screen help, and math features. Talk your club or a few of your buddies into going in with you if you can't justify $300. But a decent oscilloscope is worth what you pay for it. 

Speaking of Rigol equipment, several years ago I saved my toy money and bought a Rigol DSA-815 spectrum analyzer with a tracking generator. For the money you can't beat it. Besides measuring stuff like spectral purity and TX IMD3 you can also measure filters and tune duplexers, check coaxial cable loss, and a host of other things. 

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