High impedance probe for MSO5000 scope ? - Page 1
Forum section: electronics / testgear

author: Sharp
author_rank: Contributor
timestamp: August 23, 2021, 07:41:07 pm
content: Hi guysI need a high impedance probe for my MSO5000 scope – I believe in the area of 25 – 50 Mega ohmAny suggestions ?

author: Sharp
author_rank: Contributor
timestamp: September 01, 2021, 01:46:59 pm
content: Hi GuysI asked around and have found this probe - Testec TT-HV-150 100MOhm input impedance - I believe it can solve my problem.Link to Testec TT-HV-150:https://www.batronix.com/versand/messtechnik/tastkoepfe/Testec-TT-HV-150.html

author: Sharp
author_rank: Contributor
timestamp: November 06, 2021, 08:38:02 pm
content: Hi GuysJust a follow up my on my 4 pcs x100 probes to my MSO5000. The probes are high voltage TESTTEC 2500Vp CAT I TT-HV-250 100M ohm - works perfect !!!!!!!!

author: bdunham7
author_rank: Super Contributor
timestamp: November 06, 2021, 08:49:26 pm
content: Those look very good. I wish there was a US seller. Do you have an accurate HV source so that you can test the voltage coefficient?

author: Sharp
author_rank: Contributor
timestamp: November 07, 2021, 05:01:11 pm
content: @bdunham7No sorry, but below are the links to the data sheet and to the company's homepage. I bought mine at Batronix (German company)https://www.batronix.com/shop/index.htmlhttps://www.batronix.com/shop/measurement/probes/Testec-TT-HV-250.htmlhttps://www.testec.de/en/Br Sharp

author: BRZ.tech
author_rank: Regular Contributor
timestamp: June 11, 2022, 06:26:25 pm
content: Quote from: Sharp on August 23, 2021, 07:41:07 pmHi,1. I checked the TT-HV-250 probe specs from the link:https://www.testec.de/assets/pdf/TT-HV/TT-HV-250_Datasheet_DE.pdfI find it interesting to analyze the “Voltage vs Frequency Rating Curve” of this probe, and all other similar ones.In the case of the TT-HV-250 probe, the isolation and maximum voltage of 2500Vp goes from Zero to just above 1MHz. At 100 MHz, the Vpmax = 20V. At 300MHz, the Vpmax < 10V.2. I bought the probe 100:1 - 250MHz - model P4250 for my MSO5000, on Aliexpress:https://pt.aliexpress.com/item/32350679999.html?spm=a2g0o.store_pc_groupList.8148356.18.8b5d2f70aIK72e&pdp_npi=2%40dis%21BRL%21R%24%2093%2C96%21R%24%2079%2C85%21%21%21%21%21%402100bb5116549624915247470e55b7%2151850066002%21shAttached I send the PDFs with the probe specifications: P4250, P6100, P6500, PV2350. The probe that comes with the MSO5000 is the PV2350.In the case of Hi Voltage Probe, the P4250 is 100:1 and Bandwidth = 250MHz.You should look at the P4250's “Voltage vs Frequency Rating Curve” graph, and verify that insulation and maximum voltage of 2000Vpp goes from Zero to just above 70KHz. At 1MHz, the Vmax = 200VAC. From 10MHz to 1GHz, the Vmax < 50VAC.3. This “Voltage vs Frequency Rating Curve” graph greatly limits the use of all these probes at high frequencies and with high Vpp, such as HF: 30MHz, VHF: 146MHz, UHF: 440MHz.4.Suggestion: I made an Extra GND Cable here, connecting the Ground Terminal of the Oscilloscope, with some Safe GND from the board to be tested. With Alligator Clip.So, if any bad contact occurs on the Probe's GND, the high voltage does not enter the oscilloscope channel in use.In this situation, the measurement will have 2 GND cables, the probe cable, and the extra cable with Alligator Clip.The 2 cables will be in parallel, and the RF chooses the best path for it, which will be the probe's GND cable.When the measurement is extremely safe, you can remove the cable with the Alligator Clip.And saves the life of the Oscilloscope....5. I didn't find any kind of probe, with attenuation 100:1 and V> 2000V where the specifications work in HF, VHF, UHF frequencies... with hight voltage.6. Ask everyone: how to safely measure an HF signal, eg 28MHz, with Vpp = 70V, at Dummy Load = 50 Ohm. This on an Output Power = 100W HF communications radio?Question everyone: how to safely measure a VHF signal, eg 146MHz, with Vpp = 50V, at Dummy Load = 50 Ohm. This on a VHF communications radio of Power = 50W?All the best to everyone.BRZ.tech