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Which probes for my first scope?

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jimmy74

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Joined 2009
#1
Will soon be recieving my first scope a tektronix 465B with DM44 integrated. First off which preliminary tests would let me know it's functioning properly before actually buying a pair of probes?
Secondly if it passes the tests, what model probes would be right for this scope? Working mainly with tube amps so I know that a pair of 10x 100mhz 600v would be right, but which model probe has these specs? Should it be passive or ???

thanks
J.
 
#2
I suspect any of the ones in the P6100-series would work. Personally, I use the P6139 500 MHz probe. The P6100 is a 100 MHz 1x/10x switchable probe. That might be perfect for you...

You may consider getting a 100x probe as well. Though, usually, I find myself using a high-pass filter made from a 1 uF cap and a 1 Mohm resistor for looking at AC components on B+ and such. That removes the need for a 100x probe.

Get a passive probe. The active ones are rather spendy and tend to only be good for low voltage signals.

To test your scope, hook the input to the CAL output on the scope. On that scope, I believe the CAL output is a metal hoop on the front panel by the inputs. That should result in a square wave on the scope screen (the settings to use should be indicated on the front panel). Ideally, you'd use an oscilloscope probe for this, but you can at least get a trace on the screen if you just connect the CAL to the input with a piece of wire.

Once you get probes, you'll want to calibrate them. See how that's done here:
http://cheme.eng.wayne.edu/neuron/auth/ece3310/probe_calibration.htm

~Tom
 
#3
Get a "coded" probe. They have the "tang" that tells the scope to accuratize the ratio you see on the screen. Otherwise you have to do math in your head.

I compiled specs when I was searching for mine. I found no complete listings. Here's a paste of it:

Part # CODED ratio MHZ xPFx xTIPx
P2100 ??? 1X-10X 100 15-35 ???
P2200 NO 1X-10X 200 15-25 ???
P2200 NO 1X-10X 200 15-25 ???
P2220 ??? 1X-10X 200 ??? ???
P3010 YES 10X 100 15-35 ???
P5050 YES ??? 500 ??? 3.5
P5060 ??? 1X-10X 60 20-40 ???
P5100 YES 100X 250 7-30 ???
P5102 ??? 10X 100 ??? ???
P5120 ??? 20X 200 15-25 ???
P6002 NO 100X 30 20-50 ???
P6005 NO 100X 30 20-50 ???
P6006 NO 10X 30 20-47 ???
P6007 NO 100X 50 20-47 ???
P6008 ??? 10X 120 15-47 ???
P6009 option 100X 120 8-47 SCREW
P6010 ??? 10X 50 14-21 ???
P6011 NA 1X 33 15-47 ???
P6011 NA 1X 33 15-47 ???
P6011 NA 1X 33 15-47 ???
P6012 ??? 10x ??? ??? ???
P6013A ??? 1000x ??? ??? ???
P6015 ??? ??? 90 12-50 ???
P6015A ??? 1000x 75 7-49 ???
P6021 ??? ??? ??? ??? ???
P6022 ??? ??? ??? ??? ???
P6028 NA 1X 17 ??? ???
P6028 NA 1X 17 ??? ???
P6046 ??? ??? ??? ??? ???
P6047 ??? 10X 290 15-20 ???
P6053B NO 10X 250 15-24 ???
P6055 YES 10X 60 20-27 ???
P6056 ??? 10X 3.5G ??? ???
P6057 YES 100X ??? ??? ???
P6060 ??? 10X 100 15-55 ???
P6062B YES 1X-10X 100 15-47 ???
P6063B NO 1X-10X 200 15-24 ???
P6065A ??? 10x ??? ??? ???
P6100 ??? 1X-10X 100 ??? ???
P6101 NA 1X 34 NA ???
P6101A NA 1X 8-34 32-78 ???
P6101B NA 1X 15 NA ???
P6102A ??? 10X 60 36-55 ???
P6103 ??? ??? ??? ??? ???
P6104A ??? ??? ??? ??? ???
P6105 YES 10X 100 ??? ???
P6105A YES 10X 100 15-35 ???
P6106 YES 10X 250 15-35 ???
P6106A ??? ??? ??? ??? ???
P6106A YES 10X 250 15-35 ???
P6107A ??? ??? ??? ??? ???
P6108 NO 10X 100 ??? ???
P6108A NO 10X 95 15-35 ???
P6109 YES 10X 150 15-35 ???
P6109A ??? 10X ??? ??? ???
P6109B YES 10X 100 15-35 ???
P6109B YES 10X 100 15-35 ???
P6110 ??? ??? ??? ??? ???
P6111B YES 10X 200 15-35 ???
P6112 NO 10X 100 15-35 ???
P6113B ??? ??? ??? ??? ???
P6114B YES 10X 400 10-35 ???
P6115 ??? ??? ??? ??? ???
P6117 NO 10X 200 15-35 ???
P6119 ??? ??? ??? ??? ???
P6119B ??? ??? ??? ??? ???
P6120 NO 10X 60 23-51 ???
P6121 YES 10X 100 20-26 ???
P6122 NO 10X 100 15-35 ???
P6125 ??? ??? ??? ??? ???
P6129 ??? ??? ??? ??? ???
P6129B ??? 1X-10X 100 15-35 ???
P6130 YES 10X 250 15-35 2.5
P6131 YES 10X 300 14-18 2.5
P6133 YES 10X 150 13-30 2.5
P6133 YES 10X 150 13-30 2.5
P6134 YES 10X 300 12-18 2.5
P6134C YES 10X 300 12-18 3.5
P6136 YES 10X 350 12-18 2.5
P6137 YES 10X 2-400 12-18 3.5
P6138 YES 10X 250 ??? 3.5
P6138 YES 10X 250 ??? 3.5
P6138A ??? 10X 400 ??? ???
P6139 YES 10X 500 8-12 ???
P6139A YES 10X 500 8-12 ???
P6146 ??? 10X 50 20-62 ???
P6148 ??? 10X 50 ~15.5~ ???
P6148A ??? ??? ??? ??? ???
P6149 NO 10X 50 20-62 ???
P6149A NO 10X ??? ??? ???
P6201 ??? 100x ??? ??? ???
P6202 ??? 10x/100x 500 ??? ???
P6203 ??? 10x ??? ??? ???
P6204 ??? 10X 1000 ??? ???
P6205 yes 10x 750 ??? ???
P6206 ??? ??? ??? ??? ???
P6207 ??? ??? 4000 .05 ???
P6243 ??? 10X 1000 ??? ???
DL-31 NA NA ??? ??? ???
 
#5
I've found a P6009 going cheap that might be the option for the 100x probe. There seems to be a lot of chinese P6100 on ebay. There are a couple of 6105's but they have max voltage set at 500v. The manual doesn't seem to specify reccomended probes, except the P6065 for use when testing the scope itself.
 
#6
Rather than just buying stuff, look at your actual needs. Also note that if you're using AC coupling on the scope, the AC coupling cap in the scope will see the full DC voltage of your circuit under test. It may not like that so much... So you'll end up building your own HP filter like I described above anyway. It all depends on what you need to measure.

As jjman said, get a probe that allows for automatic detection of 1x, 10x, etc. if your scope supports it. That really improves life in the lab...

There are tons of probes available on eBay. Spend a little more and get the real Tek probes. There's nothing worse than cheap tools.

~Tom
 
#7
Thanks for the reply Tom... I must admit that all of this is new to me... so knowing what my scope can and cannot do is a big mystery to me. All I can say is that I mainly work on tube powered equipment and guitar amplifiers, my scope is a 465B (still in the post and I have to verify it's working properly once it arrives) but in the meanwhile I thought I might get some expert knowhow on which probe would cover the biggest range of testing based on the work I do.
As for what jjman has written, and I thank him too, but all that information is peanuts to me. Which model probe does have that option and would cover my needs too? What would be needed to build that HP filter? I will definitely head for a Tek probe and I'm staying well away from the chinese stuff... that's one of the reasons I posted my question here.

thanks
 
#8
A HP (high-pass) filter can be made by connecting a 100 nF capacitor in series with a 220 kOhm resistor. Connect one end of the capacitor to the voltage under test, the node between the resistor and the capacitor goes to the o'scope probe, and the other end of the resistor goes to ground. This filter has a cut-off frequency of about 10 Hz. The capacitor will need to be rated for operation at the DC voltage of the signal being measured.

The HP filter is useful for looking at ripple voltages or other AC signal components. It blocks DC. Use a voltmeter for looking at DC voltages.

High-pass filter - Wikipedia, the free encyclopedia

BTW, there's nothing wrong with buying a low cost probe. Just don't buy it on eBay. Go through one of the well reputed electronic component distributors like Digikey, Farnell, Newark, RS, et al. I paid $45~50 for my 100x probe. I don't use it very often, so I had a hard time justifying spending much more than that. The Tek P6139 I use run $400 each from Tek. I happened to find a good deal on eBay and payed much less ($75 each, I think).

~Tom
 
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#10
P6105 probes were OEM standard equipment with the 465.
 

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#11
Ok the stock probes on the 465 scopes were the P6105's (not sure what the difference is with the 6105A's). Though it seems that the probe which has the 1x/10x with the readout pin is the suggested P6062B or P6063B. As someone suggested, working with audio equipment I will be needing 2 probes, so my question is do I need to have both probes being the same model or can I have say a P6105 and a P6062 and use them together?

thanks
 
#13
Well I've just received my 465B scope, there's one thing to do before turning it on - change the fuse. Euro voltage is around 230v and on the back of the scope it says 0.75A Fast.... would a 1 amp fuse be ok?
Also I can hear something rattling around on the inside... be best to take it apart before turning it on?
Where can I find the leads for the DM44 tester?

thanks
 
#14
Just powered on and all seems to turn on correctly, I tried using a wire from the CALIBRATION Bridge to the centre pin of the BNC connector on both channels but the horizontal line doesn't seem to change.... maybe there's some sort of setting that I'm missing out on... does anyone know how to go about this on a 465B?

thanks
 
#15
The cal output is only 0.3 V, so set the input to 0.05V/Div or 0.1 V/Div, set coupling to AC or DC (not GND!). It is 1 kHz, so set the horizontal to 200µSec/Div. Set the trigger to the channel being tested, to "auto" mode, and set the level around zero/midpoint. There is a "TRIG" lamp that will light if the A trigger is firing properly. If you still can't get a display, the scope may not be working, or maybe just the calibrator is not sending a signal, though that's less likely than a more serious failure.

As for probes, if you can get the originals, P6105 someone else said, then that is worth it. The high frequency compensation (not the be confused with the low frequency compensation) should be already adjusted to closely match the HF characteristics of the scope. Other probes, even other Tek probes, will not usually match as well. They can usually be adjusted, but you need a good quality fast rise-time pulse generator to do it. I have some cheap generic probes as well as some orginal Tek ones, and they all work very well once adjusted to match the scope.
 
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#17
Thanks Macboy, I quickly tried the settings you suggested and there is signs of a pointy waveform on the screen on both channels though very blurry and this dissappears if I touch the calibration bridge with the wire that goes to the input plug. I have ordered a P6063B and I am currently looking for a P6105A. The focus control is very stiff.... anyways does this sound right to you?
 
#19
I thought you were using wire for a temporary probe. Don't forget a ground clip. A horizontal line is about all you can hope for with no input. Feed a signal from your PC or mp3 player across a resistor for a signal generator. Or breadboard a simple oscillator.
The DM44 can use standard banana plug DMM leads that connect to the jacks on the side of the unit.
 
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