With all the talk of cable and connector quality, what (and where from in UK) would qualify as reasonable up to say 150Mhz, for a BNC to BNC patch?
Rigol DS2202, DG4000:
I hope your DG4000 wasn't set to 50% duty cycle
That was from a Rigol DG4000 series at 40MHz with a rise time less than 2ns? Must be either a DG4162 or maybe a DG4102. Either way, impressive. (I'm betting you had it set to something other than 50% duty cycle.)
Rigol DS2202, DG4000:
I hope your DG4000 wasn't set to 50% duty cycle
That was from a Rigol DG4000 series at 40MHz with a rise time less than 2ns? Must be either a DG4162 or maybe a DG4102. Either way, impressive. (I'm betting you had it set to something other than 50% duty cycle.)If it's other than 50% duty it's a PULSE and EF asked for squarewaves.
Rigol DS2202, DG4000:
I hope your DG4000 wasn't set to 50% duty cycle
That was from a Rigol DG4000 series at 40MHz with a rise time less than 2ns? Must be either a DG4162 or maybe a DG4102. Either way, impressive. (I'm betting you had it set to something other than 50% duty cycle.)If it's other than 50% duty it's a PULSE and EF asked for squarewaves.
Which is more challenging to produce? A pulse?
With all the talk of cable and connector quality, what (and where from in UK) would qualify as reasonable up to say 150Mhz, for a BNC to BNC patch?
http://uk.pasternack.com/
http://www.hubersuhner.com/en-gb/
I buy my BNC RG-58 and other RF cables from them.
Like the video DAC. Show some pictures of the board!
OMG I just hooked up my Wun Hung Lo factory signal generator to my Tektronics TDS 2014B 100Mhz scope. A 1Mhz square wave looked so bad it won't sync to it. The edges have so much ringing on them that it's impossible to see a flat spot. It just looks like hair in a mullet pattern. I even tried different cables and lower frequencies. No better.
There is a small section on the top of the waveform where a flat spot can be seen. So that leads me to believe it is in fact a square wave.
Looks like I am going to save up for a new signal generator next.
I appreciate this thread. It got me off my bum and made me look.
Thanks!
As long as we are wandering around the topic a bit, and not to state the obvious, but in case it helps anyone, if you want to compare the effect of cables (different materials, lengths, etc.) an easy way to do it is to attach two alternative cables to a two channel generator and set the channels for tracking - then change frequencies, amplitude, etc. and watch rise times and fall times, etc. on your scope.
Rigol DS2202, DG4000:
I hope your DG4000 wasn't set to 50% duty cycle
That was from a Rigol DG4000 series at 40MHz with a rise time less than 2ns? Must be either a DG4162 or maybe a DG4102. Either way, impressive. (I'm betting you had it set to something other than 50% duty cycle.)
Hah, I was wondering how you managed to get such a nice square wave out of a DG4000.
Here is a DG4062 (mod -> 'DG4202') and DS1054Z (mod -> DS1104Z) using the sync output:
Jeez... Some of the low frequency squarewave plots from the modern stuff from Rigol and Siglent are less than impressive.
I'm not really into pulse risetime races but I do have some ancient and low spec pulse generators from the 1970s here. eg the bargain basement 10MHz models from HP or Datapulse and they produce nicer square waves at 1MHz and 5MHz. (HP8002A and Datapulse 101) The Datapulse claims a risetime of 5ns and the HP is about 10ns. I paid £5 for each of them about 20yrs ago at a ham surplus sale.
Do people really accept that level of performance from Rigol? Looks woeful compared to basic old school stuff that was designed and built about 40 years ago.
Note: I just noticed that the later plots from the Siglent gear look to be better. So maybe the first plot was poorly set up?
QuoteBernice thank you for your fresh input, no doubt you have more to offer.
Can I make the suggestion that you quote before your reply as it makes the post easier to read.
Sort of like how I've amended your last post.
Save your breath. He's pretty deaf on that ear
Hah, I was wondering how you managed to get such a nice square wave out of a DG4000.
Here is a DG4062 (mod -> 'DG4202') and DS1054Z (mod -> DS1104Z) using the sync output:
You have mod DG202. What is the frequency of sync output if you set output to 200 MHz sine? Is it 50 MHz square wave pulse or is it still 40 MHz?
In the circuit diagram the light bulb is only used as a battery check and there is a thermistor for temperature feedback. Of course the thermistor might actually be another light bulb - I've not taken it apart to have a look yet.
There are a great number of variables at work here. Everything from cables, connectors, overall set-up, instrumentation and more affect the visual results.
If one were to dig into vintage pulse/square wave generators there are often a number of adjustment to get optimized pulse response at the output. Notables would be EH-Research, Datapulse, Hewlett-Packart, Tektronix and others.
There was a time when folks who worked with this stuff really cared about pulse quality to where it was an engineering speciality (aka pulse engineer). This work was part of early digital where the industry was trying to figure what was do-able, what was not and how good pulses had to be to transmit data with reliability and be robust in a system.
This was the age of tunnel diode, snap diode, hot carrier diode clamped and similar devices were used in pulse / step wave form generation. The picosecond race was on.
In time, high speed logic evolved as the industry gained a much better understanding of how to make pulses go fast, be reliable and more. ECL is a good example of fast logic that can offer low noise if implemented properly. The Hewlett Packard 8640 RF signal generator uses a cavity oscillator with a group of ECL dividers and filters to produce a highly stable and low distortion RF sine wave.
Bottom line, newer is not always better. Often times vintage test gear is looked down upon as old. obsolete and in-the-way-boat anchor. When on balance it really depends on what the measurement needs are as the latest and greatest is not always the ideal solution to any given problem. The ideology of smaller is always better should not be the single parameter of desirability.
The following screenshots show again a 1MHz and a 20MHz square wave from a Rigol DG1062z, but this time the scope (LeCroy WavePro 7300A) was running in 11bit ERES mode which limits the bandwidth to 160MHz (which eliminates some of the noise).