Which One - TA043 or TA042?

Which product is right for your exact requirements
Post Reply
Oldjaguy
Newbie
Posts: 1
Joined: Sat May 04, 2019 3:22 pm

Which One - TA043 or TA042?

Post by Oldjaguy » Sat May 04, 2019 3:37 pm

I want to purchase either the Pico TA043 (100mhz, 10/100:1) or TA042 (100mhz, 100/1000:1) active differential probe. The 100/1000:1 is actually cheaper than the 10/100:1 probe. Is there a reason I should buy the 10/100:1 probe instead of the 100/1000:1 probe? Is the 10/100:1 probe more sensitive (or other reason) than the 100/1000:1 probe?

I will be using the probe to troubleshoot shorepower (220vac) issues on my boat, as well as VHF/SSB radio noise issues. Thanks.

Gerry
PICO STAFF
PICO STAFF
Posts: 439
Joined: Mon Aug 11, 2014 11:14 am

Re: Which One - TA043 or TA042?

Post by Gerry » Tue May 07, 2019 2:27 pm

Hi Oldjaguy,

The answer to your question is that actually, the 10/100:1 probe has a lower sensitivity (change in output level for the same input level), because it has smaller attenuation ranges. However, what is important is that the probe can handle larger voltages with the same attenuation range. What counts in practice is where your measurement lies within the ranges of the probes. So, for the 10/100:1 probe a 220 Vac measurement will be in the 100:1 range, while for the 100/1000:1 probe it will be in the 1000:1 range (because of the upper 140V limit of the 100:1 range). So, the 100/1000:1 probe will be applying more attenuation, which means reduced accuracy, and a higher noise floor (as you will be using a lower voltage range on the device you are using to digitize and display the voltage).
Also, note that the 10/100:1 probe (TA043) can measure at the top of it's maximum voltage range without getting anywhere near it's absolute maximum voltage input limit, while the 100:1000:1 probe needs to be at its absolute maximum voltage input limit in order to measure at the top of its maximum voltage range (so it has a higher risk of damage if working at those extremes of voltage), but this clearly doesn't affect your specific measurement application.
So, the TA043 will give you a better (more accurate, less noisy) measurement at 220VAC, while the TA042 will allow you to ultimately measure a larger voltage, but with the caveat that you need to stay away from the highest measurable voltage to avoid the risk of damaging the probe.

Regarding measuring RF noise, I'm assuming that the reason for your question is that, either you have an Oscilloscope, a Multimeter (or are going to get one) with passive probes having a smaller bandwidth than the 100MHz of the TA042 and TA043.

So, the answer is that the Active Differential probes are not ideal for measuring VHF/SSB radio noise issues as their bandwidth limit is 100MHz (Marine VHF frequencies are 156 to 174MHz), so there will be some roll-off in the signal that you capture. If you then also add to that, the fact that the (typically low voltage) signal, will be attenuated by a factor of 10 or 100 (depending upon which probe you select) and that the noise of the probes is typically about 1mV, then when using a scope or meter on a lower level input range, with more noise, you could end up trying to measure radio noise in equipment with a high cumulative noise floor.

In addition to that, the differential probes have non screened leads from the probe body to the tips, which will be prone to pickup of induced signals. Because the probes are differential a significant amount will be removed by the differential inputs, however as the leads are not closely coupled, there will still be differences between the signals induced onto the cables, and therefore significant additional unwanted interference (unless you were to somehow work with them twisted together).

Regards,

Gerry
Gerry
Technical Specialist

Post Reply