TDS1002 Upgrade toTDS1012

The TDS1002 is a 60Mhz, 1G/S 'scope, but the hardware is capable of running up to 100MHz, when it is then badged as a TDS1012. These notes show how I upgraded my 1002 to a 1012.

The procedure to upgrade has two main steps, first update the 'scope model number via the RS232 interface, then run it through the factory calibration procedure. It will then operate as a TDS1012.

My understanding (but I have no direct experience of other models) is that the same procedure is used for the TDS1000 and TDS2000 series of 'scopes.

The first step is relatively easy, the second not so. There are a total of 70 steps to perform, first by inputting various DC voltages, then by applying various RF inputs. It took me several attempts to finally get this all to happen without the 'scope complaining and failing a step, and here are the main take aways:

  • When any one step fails, you have to go right back to the begining and start again.
  • The input impedance of the 'scope varies during some of the DC voltage the steps (attenuators changing maybe) and so it is important to feed it with a low source impendence, or the input can vary, even slightly, and the cal will fail.
  • The input impedance at 100MHz (the BWL in this case) seems not to be 1Mohm. The RF level drops slightly (about 1db) when attaching the 'scope. (could have been something to do with my test set-up, but I don't think so...)  So I compensated for this.
  • Consistency is important. Any deviation from the expected value and the step will fail. 

The tables below show the cal steps. Take note you need to be able to supply from 5kHz at 4dBm to 100MHz at 18dBm.  So quite a challenge. I used two signal generators and an RF power module to cover all steps.



1. The programming bit;

I used this USB to RS232 adapter to connect to the 1002. (I believe the GPIB will work too if you have an interface for that.)  



You then need the Tektronix software (TekVISA), downloadable from their website to talk to the 'scope.


First run the Instrument Manager and it should pick up the serial interface automatically. Then click on the Start Application or Utility button, a new window pops up and from there, select Tools, and Talker Listener. You will then get the main window shown in the photo. 

First write *IDN? (will be filled in by default), then read *IDN?, by clicking the write and read buttons, and if it's talking it will come back with the TDS1002 info as shown.

Then write:

PASSWORD PITBULL

MODEL TDS1012

and if you then repeat the write/read with *IDN? it should return with the updated model, as you can see.

Then it's time for the factory calibration. You need to follow a certain key press sequence to get it into service mode, details are in the manual, page 5-5.




Looks scrappy I know, but did the job!


2. For the DC voltage steps;

I used an op-amp as a voltage follower (with 4.7uF on its output) to feed the 'scope, and with a 2.5v reference module fed via a multi-turn pot on the input.  This allowed me to set all steps from 2.0V down to 15mV. And, yes, just a baulk standard DMM to set the voltage. (I checked it against other kit I had and it came out just as accurate as anything else).  I included a changeover switch to go from negative inputs to positive ones - saved fiddling about with connections and risking a mistake. The 20V step was done with a bench PSU. 

The mV steps are a real pain and would be much better done with a (expensive) programmable PSU, but I managed with this set-up.



3. For the RF steps;

I used a Marconi 2022 sig gen (love that thing) for most of the steps (having programmed it the previous evening to speed things up), plus a Philips PM5193 (not loved as much, but still useful) for the lowest frequency inputs. And the RF power module you can see to get me the highest RF levels. 

The 50ohm load you can see is actually a 40dB attenuator with a TinySA attached so I could check the RF levels. (Note the adjustments needed at 100MHz mentioned above.)

The steps that need a square wave going from 0 to - 800mV was done with a function generator. The instructions ask for the 50ohm load to be attached, but I found the generator would not go down to -800mV with the load attached. So I did it without. Worked ok.

It took me an hour to complete and, boy, was I getting twitchy towards the end hoping not to see the Cal Fail text appear. But was rewarded with the word all Tek owners look forward to seeing: PASS.




There she is with a 100MHz signal input at about 0dBm.







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