Topics

Cool cheap oscilloscope for troubleshooting

Tom, wb6b
 

Hi,

Anyone looking for a low cost scope to trouble shoot (a least audio and low frequency such as encoders) parts of their UBitx, these little oscilloscopes were on sale. I bought one. It only has a 1 Mhz bandwidth, but that is better than the 200 Khz bandwidth on many of the other cheap tiny scopes. 

So far I've liked it and have use it for observing some pulse width modulate signals where the frequency and duty-cycle readouts were handy. It is totally isolated when running on its battery. That is a nice feature. 

I have another radio with an intermittent causing both the transmit power and receive signal strength to abruptly change. Am planning to make an RF detector probe with a diode and capacitor and just leave this little scope attached to various points in the RF chain to see where I see the signal change in step with the change in my transmit power or S meter on receive (particularly the background noise floor on the S meter). This little scope won't take up a bunch of room while doing these measurements and may provide me with a little more interesting information than a DVM. 

https://www.banggood.com/DSO188-Pocket-Digital-Ultra-small-Oscilloscope-1M-Bandwidth-5M-Sample-Rate-Handheld-Oscilloscope-Kit-p-1315186.html?rmmds=home-mid-relatedViewed&cur_warehouse=CN

Here is a review on a site that specializes in trying out low cost Chinese electronic gizmos. Not sure if my later model is calibrated better than the one he tested, but did not strike me as really bad. 

https://chinese-electronics-products-tested.blogspot.com/p/dso188-matchbox-scope-tested.html

Tom, wb6b

----

----

Don--AE4DW
 

Another good cheap option is the the DSO150 from JYETech. They come in varying kit forms, and are a cheap useful little scope. You have to be careful with the JYETech series as there are all kinds of clones with pirated firmware, so if you go this route, make sure it is actually from JYETech.

It will never be mistaken for a good lab grade Tektronix scope, but will suffice for quick and dirty troubleshooting.

https://jyetech.com/

Ashhar Farhan
 

The oscilloscope is a very useful tool. But you will need something that goes upto at least 50 Mhz. Dont invest in anything less than 20 Mhz. A second hand tek from ebay will be a good bet.
Alternatively, you can build an AD8307 based power meter. This can cost less than ten dollars and measures power upto 500 mhz.
- f

On Tue 30 Jul, 2019, 5:56 PM Don--AE4DW, <dwinflorida@...> wrote:
Another good cheap option is the the DSO150 from JYETech. They come in varying kit forms, and are a cheap useful little scope. You have to be careful with the JYETech series as there are all kinds of clones with pirated firmware, so if you go this route, make sure it is actually from JYETech.

It will never be mistaken for a good lab grade Tektronix scope, but will suffice for quick and dirty troubleshooting.

https://jyetech.com/

Robert D. Bowers
 

The bandwidth would be adequate to catch glitches like that, and to work with audio.  Depending on the design, it wouldn't be that useful to look at IF frequencies (except with a RF probe), and they do make 'cheap' ones that will cover up to 50 mhz or so.  It should be adequate for encoders and so on - would even have enough bandwidth to pick up encoder glitches (they do happen sometimes).  I used to have a 'pen scope' that went to 5mhz and it was very handy for the sort of work I was doing, but not so good for repairing radios.

If it interfaces with a computer (most of the ones I know of do) and you can use it to catch signals or signal changes, that would be a big help in what you're trying to do.  Also, is it single or dual trace?  Dual trace multiplies the utility of the scope, as long as you can catch both signals at the same time.  (Most are.)

I'd be interested in seeing how something like this works with a zener sweeper or curve tracer - VERY useful add-ons for a scope.

Bob

N4FBZ


On 7/30/19 2:50 AM, Tom, wb6b wrote:
Hi,

Anyone looking for a low cost scope to trouble shoot (a least audio and low frequency such as encoders) parts of their UBitx, these little oscilloscopes were on sale. I bought one. It only has a 1 Mhz bandwidth, but that is better than the 200 Khz bandwidth on many of the other cheap tiny scopes. 

So far I've liked it and have use it for observing some pulse width modulate signals where the frequency and duty-cycle readouts were handy. It is totally isolated when running on its battery. That is a nice feature. 

I have another radio with an intermittent causing both the transmit power and receive signal strength to abruptly change. Am planning to make an RF detector probe with a diode and capacitor and just leave this little scope attached to various points in the RF chain to see where I see the signal change in step with the change in my transmit power or S meter on receive (particularly the background noise floor on the S meter). This little scope won't take up a bunch of room while doing these measurements and may provide me with a little more interesting information than a DVM. 

https://www.banggood.com/DSO188-Pocket-Digital-Ultra-small-Oscilloscope-1M-Bandwidth-5M-Sample-Rate-Handheld-Oscilloscope-Kit-p-1315186.html?rmmds=home-mid-relatedViewed&cur_warehouse=CN

Here is a review on a site that specializes in trying out low cost Chinese electronic gizmos. Not sure if my later model is calibrated better than the one he tested, but did not strike me as really bad. 

https://chinese-electronics-products-tested.blogspot.com/p/dso188-matchbox-scope-tested.html

Tom, wb6b

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----

Attachments:

Robert D. Bowers
 

Good suggestion.  I prefer analog to digital for RF work anyway - I feel you can 'see' more with it.  There sometimes is a learning curve to using a digitizer.

The AD8307 suggestion, by the way, is a sound one.  I built one - in an RF tight case, with an arduino programmed to convert the output of the AD8307 to USB output.  You have to REALLY isolate the 8307 from the arduino, otherwise it looses a lot of sensitivity, but if done right is a fantastic tool to use.  I use it as a building block combined with other homebrew equipment (such as a programmable signal source) for doing all sorts of measurements.

Bob

On 7/30/19 11:11 AM, Ashhar Farhan wrote:
The oscilloscope is a very useful tool. But you will need something that goes upto at least 50 Mhz. Dont invest in anything less than 20 Mhz. A second hand tek from ebay will be a good bet.
Alternatively, you can build an AD8307 based power meter. This can cost less than ten dollars and measures power upto 500 mhz.
- f

On Tue 30 Jul, 2019, 5:56 PM Don--AE4DW, <dwinflorida@...> wrote:
Another good cheap option is the the DSO150 from JYETech. They come in varying kit forms, and are a cheap useful little scope. You have to be careful with the JYETech series as there are all kinds of clones with pirated firmware, so if you go this route, make sure it is actually from JYETech.

It will never be mistaken for a good lab grade Tektronix scope, but will suffice for quick and dirty troubleshooting.

https://jyetech.com/

Graham W
 

The links you provided are full of Malware !!! I have to re-do my windows 10 machine because of the malware.....
Please use caution on clicking links....

Graham VE3WGW

Tom, wb6b
 

On Tue, Jul 30, 2019 at 08:12 AM, Ashhar Farhan wrote:
AD8307 based power meter
That is a good idea. I have some eBay boards with the AD8307 and similar chips already. Should be better than a diode and capacitor RF probe.

The advantage of the tiny scope over a DVM, even if its bandwidth is only 1 Mhz, is in many places I may be probing in the SSB HF transceiver the signal will be envelopes modulated by the audio rather than steady state. The little oscilloscope will let me see the shape of the envelopes. The DVM will not. 

Sorry to the person that got malware. I've repeatedly clicked on those links, as well as when I went to the sites originally and have not had any malware issues with the links or when I originally visited the sites. But never know, the sites could have had a short term issue with being hacked and the sites fixing the issue. I assume if there was an issue it only affected one of them. You did not specify which one to be careful about. 

Tom, wb6b

 

Very odd, not found any malware. McAfee and Malwarebytes.

Raj

At 31-07-19, you wrote:
The links you provided are full of Malware !!! I have to re-do my windows 10 machine because of the malware.....
Please use caution on clicking links....

Graham VE3WGW

Don--AE4DW
 

No malware indication here either..not sure exactly what link is suspected as being the culprit, but sounds like there was already an existing "infection"..

Don--AE4DW
 

As far as the scope options itself goes, I now realize Tom was referring to the JYE and clones I referenced when he mentioned 200 khz bandwidth, lol. Comparing specs, yes, that little matchbox unit seems to leave the JYE in the dust to some extent. The good thing is, for a 30 dollar investment and a definite impulse buy, you don't get too frustrated by limitations. I might need to read up on Tom's recommendation and try one out.

Roy Appleton
 

"Of all the cheap oscilloscopes we have tested, we are the most impressed with this DSO188. Despite the small dimensions, the scope is easy to operate and the oscillogram is easy to interpret. It is easy to live in practice with a service life of about ninety minutes with one battery charge.
The only unfortunate thing about this beautiful device is that the DSO188 cannot be used to reliably measure the numerical values of the input signal. The manufacturer should have omitted this option, because a measurement function that is 'for reference only' is not very useful in practice. "

Roy 
WA0YMH

On Tue, Jul 30, 2019, 1:50 AM Tom, wb6b <wb6b@...> wrote:
Hi,

Anyone looking for a low cost scope to trouble shoot (a least audio and low frequency such as encoders) parts of their UBitx, these little oscilloscopes were on sale. I bought one. It only has a 1 Mhz bandwidth, but that is better than the 200 Khz bandwidth on many of the other cheap tiny scopes. 

So far I've liked it and have use it for observing some pulse width modulate signals where the frequency and duty-cycle readouts were handy. It is totally isolated when running on its battery. That is a nice feature. 

I have another radio with an intermittent causing both the transmit power and receive signal strength to abruptly change. Am planning to make an RF detector probe with a diode and capacitor and just leave this little scope attached to various points in the RF chain to see where I see the signal change in step with the change in my transmit power or S meter on receive (particularly the background noise floor on the S meter). This little scope won't take up a bunch of room while doing these measurements and may provide me with a little more interesting information than a DVM. 

https://www.banggood.com/DSO188-Pocket-Digital-Ultra-small-Oscilloscope-1M-Bandwidth-5M-Sample-Rate-Handheld-Oscilloscope-Kit-p-1315186.html?rmmds=home-mid-relatedViewed&cur_warehouse=CN

Here is a review on a site that specializes in trying out low cost Chinese electronic gizmos. Not sure if my later model is calibrated better than the one he tested, but did not strike me as really bad. 

https://chinese-electronics-products-tested.blogspot.com/p/dso188-matchbox-scope-tested.html

Tom, wb6b

----

----

Ashhar Farhan
 

An easy way to extend the upper frequency range of an oscilloscope is to use a 'down converter' - a diode mixer driven by a VFO, like a direct conversion receiver. The mixer output is fed to the oscilloscope.
About ten years ago, I wrote in a blog post that serious homebrewing needs a good scope. I must revise my claim. You need a spectrum analyzer of some sort. The reason is that our work is frequency domain.  Our circuit blocks are filters, mixers, amplifiers and oscillators. All of them have inputs and outputs specified in terms of frequencies.
It is this realization that led to the development of antuino. But that is a separate post..

On Wed 31 Jul, 2019, 6:10 PM Roy Appleton, <twelveoclockhigh@...> wrote:
"Of all the cheap oscilloscopes we have tested, we are the most impressed with this DSO188. Despite the small dimensions, the scope is easy to operate and the oscillogram is easy to interpret. It is easy to live in practice with a service life of about ninety minutes with one battery charge.
The only unfortunate thing about this beautiful device is that the DSO188 cannot be used to reliably measure the numerical values of the input signal. The manufacturer should have omitted this option, because a measurement function that is 'for reference only' is not very useful in practice. "

Roy 
WA0YMH

On Tue, Jul 30, 2019, 1:50 AM Tom, wb6b <wb6b@...> wrote:
Hi,

Anyone looking for a low cost scope to trouble shoot (a least audio and low frequency such as encoders) parts of their UBitx, these little oscilloscopes were on sale. I bought one. It only has a 1 Mhz bandwidth, but that is better than the 200 Khz bandwidth on many of the other cheap tiny scopes. 

So far I've liked it and have use it for observing some pulse width modulate signals where the frequency and duty-cycle readouts were handy. It is totally isolated when running on its battery. That is a nice feature. 

I have another radio with an intermittent causing both the transmit power and receive signal strength to abruptly change. Am planning to make an RF detector probe with a diode and capacitor and just leave this little scope attached to various points in the RF chain to see where I see the signal change in step with the change in my transmit power or S meter on receive (particularly the background noise floor on the S meter). This little scope won't take up a bunch of room while doing these measurements and may provide me with a little more interesting information than a DVM. 

https://www.banggood.com/DSO188-Pocket-Digital-Ultra-small-Oscilloscope-1M-Bandwidth-5M-Sample-Rate-Handheld-Oscilloscope-Kit-p-1315186.html?rmmds=home-mid-relatedViewed&cur_warehouse=CN

Here is a review on a site that specializes in trying out low cost Chinese electronic gizmos. Not sure if my later model is calibrated better than the one he tested, but did not strike me as really bad. 

https://chinese-electronics-products-tested.blogspot.com/p/dso188-matchbox-scope-tested.html

Tom, wb6b

----

----

Jack, W8TEE
 

My club has a small knot of members who enjoy building stuff. Like everyone else, most of them can't justify the expense of $250 for a decent oscilloscope. One of our "serious" builders in the club upgraded his scope and donated his old scope to the club. Now anyone can use the club's scope for a project. So far, there's not been enough members wanting to use it at the same time to be a problem. This is now a benefit of being a member..access to some pretty decent test equipment. That same member gave a presentation on how to use the scope and it was well-received.

I guess my point is: Instead of spending $25-$50 on a device and may or may not be sufficient to get the job done, consider acquiring a scope for the club. A new scope good to 100MHz is about $250, but hamfest, Craigs List, and other places have good used scopes at reasonable cost. Depending upon the size and makeup of your club, it might be a viable solution.

Jack, W8TEE

On Wednesday, July 31, 2019, 10:43:48 AM EDT, Ashhar Farhan <farhanbox@...> wrote:


An easy way to extend the upper frequency range of an oscilloscope is to use a 'down converter' - a diode mixer driven by a VFO, like a direct conversion receiver. The mixer output is fed to the oscilloscope.
About ten years ago, I wrote in a blog post that serious homebrewing needs a good scope. I must revise my claim. You need a spectrum analyzer of some sort. The reason is that our work is frequency domain.  Our circuit blocks are filters, mixers, amplifiers and oscillators. All of them have inputs and outputs specified in terms of frequencies.
It is this realization that led to the development of antuino. But that is a separate post..

On Wed 31 Jul, 2019, 6:10 PM Roy Appleton, <twelveoclockhigh@...> wrote:
"Of all the cheap oscilloscopes we have tested, we are the most impressed with this DSO188. Despite the small dimensions, the scope is easy to operate and the oscillogram is easy to interpret. It is easy to live in practice with a service life of about ninety minutes with one battery charge.
The only unfortunate thing about this beautiful device is that the DSO188 cannot be used to reliably measure the numerical values of the input signal. The manufacturer should have omitted this option, because a measurement function that is 'for reference only' is not very useful in practice. "

Roy 
WA0YMH

On Tue, Jul 30, 2019, 1:50 AM Tom, wb6b <wb6b@...> wrote:
Hi,

Anyone looking for a low cost scope to trouble shoot (a least audio and low frequency such as encoders) parts of their UBitx, these little oscilloscopes were on sale. I bought one. It only has a 1 Mhz bandwidth, but that is better than the 200 Khz bandwidth on many of the other cheap tiny scopes. 

So far I've liked it and have use it for observing some pulse width modulate signals where the frequency and duty-cycle readouts were handy. It is totally isolated when running on its battery. That is a nice feature. 

I have another radio with an intermittent causing both the transmit power and receive signal strength to abruptly change. Am planning to make an RF detector probe with a diode and capacitor and just leave this little scope attached to various points in the RF chain to see where I see the signal change in step with the change in my transmit power or S meter on receive (particularly the background noise floor on the S meter). This little scope won't take up a bunch of room while doing these measurements and may provide me with a little more interesting information than a DVM. 

https://www.banggood.com/DSO188-Pocket-Digital-Ultra-small-Oscilloscope-1M-Bandwidth-5M-Sample-Rate-Handheld-Oscilloscope-Kit-p-1315186.html?rmmds=home-mid-relatedViewed&cur_warehouse=CN

Here is a review on a site that specializes in trying out low cost Chinese electronic gizmos. Not sure if my later model is calibrated better than the one he tested, but did not strike me as really bad. 

https://chinese-electronics-products-tested.blogspot.com/p/dso188-matchbox-scope-tested.html

Tom, wb6b

----

----

Robert D. Bowers
 

One of my dream purchases for radio is a functional spectrum analyzer that is reasonably accurate.  I use a dongle right now as a 'poor man's spectrum analyzer", although it has some serious limitations - like taking things in a 1mhz 'bite' at a time, plus compression of the signal makes db measurements only an estimate at best.  It works for checking for deviation or for spotting unwanted signals, but not that well.

The bottom end of my dongle is also around 25mhz... I have some parts to cobble together an up-converter, but haven't had the time to work on that (first I need to get my old HF rig going again).

I know that there are some kits out now (plus units from China) that work, but their price is outside of my reach.  Maybe things will get better!

Bob

N4FBZ

On 7/31/19 10:43 AM, Ashhar Farhan wrote:
An easy way to extend the upper frequency range of an oscilloscope is to use a 'down converter' - a diode mixer driven by a VFO, like a direct conversion receiver. The mixer output is fed to the oscilloscope.
About ten years ago, I wrote in a blog post that serious homebrewing needs a good scope. I must revise my claim. You need a spectrum analyzer of some sort. The reason is that our work is frequency domain.  Our circuit blocks are filters, mixers, amplifiers and oscillators. All of them have inputs and outputs specified in terms of frequencies.
It is this realization that led to the development of antuino. But that is a separate post..

On Wed 31 Jul, 2019, 6:10 PM Roy Appleton, <twelveoclockhigh@...> wrote:
"Of all the cheap oscilloscopes we have tested, we are the most impressed with this DSO188. Despite the small dimensions, the scope is easy to operate and the oscillogram is easy to interpret. It is easy to live in practice with a service life of about ninety minutes with one battery charge.
The only unfortunate thing about this beautiful device is that the DSO188 cannot be used to reliably measure the numerical values of the input signal. The manufacturer should have omitted this option, because a measurement function that is 'for reference only' is not very useful in practice. "

Roy 
WA0YMH

On Tue, Jul 30, 2019, 1:50 AM Tom, wb6b <wb6b@...> wrote:
Hi,

Anyone looking for a low cost scope to trouble shoot (a least audio and low frequency such as encoders) parts of their UBitx, these little oscilloscopes were on sale. I bought one. It only has a 1 Mhz bandwidth, but that is better than the 200 Khz bandwidth on many of the other cheap tiny scopes. 

So far I've liked it and have use it for observing some pulse width modulate signals where the frequency and duty-cycle readouts were handy. It is totally isolated when running on its battery. That is a nice feature. 

I have another radio with an intermittent causing both the transmit power and receive signal strength to abruptly change. Am planning to make an RF detector probe with a diode and capacitor and just leave this little scope attached to various points in the RF chain to see where I see the signal change in step with the change in my transmit power or S meter on receive (particularly the background noise floor on the S meter). This little scope won't take up a bunch of room while doing these measurements and may provide me with a little more interesting information than a DVM. 

https://www.banggood.com/DSO188-Pocket-Digital-Ultra-small-Oscilloscope-1M-Bandwidth-5M-Sample-Rate-Handheld-Oscilloscope-Kit-p-1315186.html?rmmds=home-mid-relatedViewed&cur_warehouse=CN

Here is a review on a site that specializes in trying out low cost Chinese electronic gizmos. Not sure if my later model is calibrated better than the one he tested, but did not strike me as really bad. 

https://chinese-electronics-products-tested.blogspot.com/p/dso188-matchbox-scope-tested.html

Tom, wb6b

----

----

Attachments:

Doug Hall
 

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. 

73,
Doug K4DSP


On Wed, Jul 31, 2019 at 08:03 AM, Jack Purdum wrote:
 
I guess my point is: Instead of spending $25-$50 on a device and may or may not be sufficient to get the job done, consider acquiring a scope for the club. A new scope good to 100MHz is about $250, but hamfest, Craigs List, and other places have good used scopes at reasonable cost. Depending upon the size and makeup of your club, it might be a viable solution.
 
Jack, W8TEE

SAM R BURNES
 

Another option is the Digilent Analog Discovery 2 Package. A computer connected device (see at: https://store.digilentinc.com/ham-radio-workbench-bundle/).

By using the code “HamRadioWorkbench2019” in your cart prior to checkout one can save $100.00.

Not associated with them in any way, just passing on the info.

73,

Sam
WY8V


On Jul 31, 2019, at 1:51 PM, Doug Hall <k4dsp.doug@...> 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. 

73,
Doug K4DSP

On Wed, Jul 31, 2019 at 08:03 AM, Jack Purdum wrote:
 
I guess my point is: Instead of spending $25-$50 on a device and may or may not be sufficient to get the job done, consider acquiring a scope for the club. A new scope good to 100MHz is about $250, but hamfest, Craigs List, and other places have good used scopes at reasonable cost. Depending upon the size and makeup of your club, it might be a viable solution.
 
Jack, W8TEE

Jerry Gaffke
 

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. 

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. 

Tom, wb6b
 

Someone told me they saw an old Tektronix 465 scope on eBay for $50 (probably $150 shipping :) ). That could be a good route. Hard to imaging that those scope might have cost $20,000 or more in todays dollars, and can now be bought for less than $100. They definitely were made well.

My first scope was a Knight Kit scope. I saved all school year and when summer vacation came I spent $109, if it recall, to purchase the kit and spent the summer putting it together.

This scope was only about 2 Mhz tops. But, I learned so much from it being able to "see" how so many electronic circuits worked and then start trying out designing my own circuits and projects, and seeing how they worked, or needed improvement.

This scope was my first realization that professionally designed equipment could be improved and not accepted as correct without question.  

My first experience was when a electrolytic capacitor exploded with a loud bang when I first plugged the scope in, as I waited breathlessly for the thrill of seeing my summers's work come to life in a magic little green line.

I was able to reason out the voltage rating of the capacitor (part of a cathode resistor negative bias circuit) was exceeded momentarily, on start up, so I got on my bicycle, rode down to the local electronics store and was able to confidently buy a replacement was not the exact same value. But, higher voltage and a close, but larger, capacitance value.

My second design improvement came after I discovered the wonders of the Z axes. I was having a great time feeding the video from a TV set I was fixing for a neighbor into the Z axis, syncing up the horizontal and feeding in the vertical to the X axis, and watching TV on my oscilloscope screen.  

There was a little RCA plug that shorted the Z axis input on the back of the scope when it was not in use. 

I'd been using the scope and realized I'd not replaced the shorting plug. The Z axis input was essentially a .1uF capacitor connected to the cathode of the CRT at 1,200 volts. 

I reached over and behind the scope to plug in the shorting plug. I remember how the little plug made such a loud bang as it hit the wall on the opposite side of my room. And how stunning the jolt was traveling through me. 

My next design improvement was to solder a 1M ohm resistor across the Z axis connector, inside the scope, to let the capacitor charge and equalize to the 1,200 volts on its own. So I would not become a live demonstration of RC time constants and capacitor peak charging current again.

Tom, wb6b



Lawrence Galea
 

How abut home brewing a digital wattmeter?

And a Capacitance / inductance meter
https://sites.google.com/site/vk3bhr/home/index2-html 

Enjoy 
Lawrence

On Thu, Aug 1, 2019 at 12:03 PM Tom, wb6b <wb6b@...> wrote:
Someone told me they saw an old Tektronix 465 scope on eBay for $50 (probably $150 shipping :) ). That could be a good route. Hard to imaging that those scope might have cost $20,000 or more in todays dollars, and can now be bought for less than $100. They definitely were made well.

My first scope was a Knight Kit scope. I saved all school year and when summer vacation came I spent $109, if it recall, to purchase the kit and spent the summer putting it together.

This scope was only about 2 Mhz tops. But, I learned so much from it being able to "see" how so many electronic circuits worked and then start trying out designing my own circuits and projects, and seeing how they worked, or needed improvement.

This scope was my first realization that professionally designed equipment could be improved and not accepted as correct without question.  

My first experience was when a electrolytic capacitor exploded with a loud bang when I first plugged the scope in, as I waited breathlessly for the thrill of seeing my summers's work come to life in a magic little green line.

I was able to reason out the voltage rating of the capacitor (part of a cathode resistor negative bias circuit) was exceeded momentarily, on start up, so I got on my bicycle, rode down to the local electronics store and was able to confidently buy a replacement was not the exact same value. But, higher voltage and a close, but larger, capacitance value.

My second design improvement came after I discovered the wonders of the Z axes. I was having a great time feeding the video from a TV set I was fixing for a neighbor into the Z axis, syncing up the horizontal and feeding in the vertical to the X axis, and watching TV on my oscilloscope screen.  

There was a little RCA plug that shorted the Z axis input on the back of the scope when it was not in use. 

I'd been using the scope and realized I'd not replaced the shorting plug. The Z axis input was essentially a .1uF capacitor connected to the cathode of the CRT at 1,200 volts. 

I reached over and behind the scope to plug in the shorting plug. I remember how the little plug made such a loud bang as it hit the wall on the opposite side of my room. And how stunning the jolt was traveling through me. 

My next design improvement was to solder a 1M ohm resistor across the Z axis connector, inside the scope, to let the capacitor charge and equalize to the 1,200 volts on its own. So I would not become a live demonstration of RC time constants and capacitor peak charging current again.

Tom, wb6b