Congratulations on getting the 1120 working and especially on figuring out my PCB design.
When you install the filters part of the process is calibration. Its covered on 5-3 and 5-5 section F. Does your unit have the amplifier board on the back? Is the max out 6V or 14V?
I have three generations on hand. There are minor variations we have seen. Mike said to me in an e-mail he got a sample with incorrect values from the factory as well.
He sent me a pretty comprehensive set of revs to test. i tried them but something did not work right and I have not gotten back to the project. I have some other broken stuff in front of this project. . .
On the filter board I want to do a new generation to deal with a problem that Scott Wurcer shows a fix for. Its not an issue for a noise weighing filter but the high pass filter is really limited to around .003% or so as designed with any opamp. The fix is matching impedance on the two inputs of the opamp. That requires an extra set of tuning components. I think I'll do a new layout using SMT so its easy to get everything to fit. Need to add an opamp to the circuit since the one on the MB can't get this mod.
When you install the filters part of the process is calibration. Its covered on 5-3 and 5-5 section F. Does your unit have the amplifier board on the back? Is the max out 6V or 14V?
I have three generations on hand. There are minor variations we have seen. Mike said to me in an e-mail he got a sample with incorrect values from the factory as well.
He sent me a pretty comprehensive set of revs to test. i tried them but something did not work right and I have not gotten back to the project. I have some other broken stuff in front of this project. . .
On the filter board I want to do a new generation to deal with a problem that Scott Wurcer shows a fix for. Its not an issue for a noise weighing filter but the high pass filter is really limited to around .003% or so as designed with any opamp. The fix is matching impedance on the two inputs of the opamp. That requires an extra set of tuning components. I think I'll do a new layout using SMT so its easy to get everything to fit. Need to add an opamp to the circuit since the one on the MB can't get this mod.
Friends,
I have a Boonton 1130 that is surplus for me. This is identical to the analyzer part of the 1120 (which has an oscillator). So the 1130 can be used with an external generator like those Viktor oscillators.
Anybody interested, let me know what it is worth to you, prefer pick up (Belgium or close to it).
Jan
I have a Boonton 1130 that is surplus for me. This is identical to the analyzer part of the 1120 (which has an oscillator). So the 1130 can be used with an external generator like those Viktor oscillators.
Anybody interested, let me know what it is worth to you, prefer pick up (Belgium or close to it).
Jan
Demian,
It was indeed a calibration issue, thanks for pointing me in the right direction. I thought I’d already done the calibration but it all works fine now. My 1120 doesn’t have the amp on the back and is 3v output.
I’d also be interested in trying another variation of filter on the board, I’m currently looking at the impedance matching network described in the OP176 data sheet and elsewhere, I’m guess that’s the technique you’re referring to, I’ll take a look at Scott’s article. I’m trying to model it in LTSpice first, assuming the op amp models are accurate regarding input capacitance. Maybe a non Sallen-Key filter could be the answer? My 400Hz filter adds about 4dB of 2H, the audio bandpass slightly less. I'm comforatble with doing an SMD layout, building the through hole filter boards was a nice trip down memory lane!
I was also interested in one of your posts about making a 40dB notch filter with 40dB of gain to get further down into the residual distortion, did you ever build this? Whilst it's an interesting exercise to get the Boonton 2H distortion as low as possible, you're close to what's possible with the unit, and getting over the residual 2H will be tricky. Maybe an active notch could help with a 1kHz measurement, built onto a Boonton filter board. The 1120 then compares the pre-notch level with the active notch and internal notch filter output to measure THD. Then we just add 40dB to the readout. Would that work?
Thanks for your help
Andy
It was indeed a calibration issue, thanks for pointing me in the right direction. I thought I’d already done the calibration but it all works fine now. My 1120 doesn’t have the amp on the back and is 3v output.
I’d also be interested in trying another variation of filter on the board, I’m currently looking at the impedance matching network described in the OP176 data sheet and elsewhere, I’m guess that’s the technique you’re referring to, I’ll take a look at Scott’s article. I’m trying to model it in LTSpice first, assuming the op amp models are accurate regarding input capacitance. Maybe a non Sallen-Key filter could be the answer? My 400Hz filter adds about 4dB of 2H, the audio bandpass slightly less. I'm comforatble with doing an SMD layout, building the through hole filter boards was a nice trip down memory lane!
I was also interested in one of your posts about making a 40dB notch filter with 40dB of gain to get further down into the residual distortion, did you ever build this? Whilst it's an interesting exercise to get the Boonton 2H distortion as low as possible, you're close to what's possible with the unit, and getting over the residual 2H will be tricky. Maybe an active notch could help with a 1kHz measurement, built onto a Boonton filter board. The 1120 then compares the pre-notch level with the active notch and internal notch filter output to measure THD. Then we just add 40dB to the readout. Would that work?
Thanks for your help
Andy
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Let me know how your simulation efforts go. I don't think they will help with the input related distortion stuff. I think there is enough area on the PC layout to allow for a quich breadboard of the idea and see if it helps. There are 3 cascaded filters and the last one would be hard to modify so maybe just bypassing it to see if the distortion reduction works.
There is another filter option but it trades the distortion for noise: (Sample) 3rd order Multiple Feedback Low-pass Filter Design Tool - Result - Its still worth looking at. The values setting it for 400 Hz and a Chebyshev filter at .2 dB ripple seem quite reasonable. Two 3rd order filters cascaded would get 120 dB at power line frequencies if I understand the plots.
I build a passive notch with the bypass mix and the 40 dB boost in a separate box. it works but the lack of flatness of the band reject region makes it a pain to use.
I think the distortion in the notch filters in the box can be reduced. We need to confirm its source before going further. I believe the input circuits are clean enough that they are not an issue. Its something with either the analog multipliers or the Jfet switches. The multiplier can be bypassed with the jumper but the open pin needs to be shorted to ground as I remember. I thought I simulated the notch filter in the 1120 but can't find the simulations now. I did find my notch simulations which I can share if you are interested.
There is another filter option but it trades the distortion for noise: (Sample) 3rd order Multiple Feedback Low-pass Filter Design Tool - Result - Its still worth looking at. The values setting it for 400 Hz and a Chebyshev filter at .2 dB ripple seem quite reasonable. Two 3rd order filters cascaded would get 120 dB at power line frequencies if I understand the plots.
I build a passive notch with the bypass mix and the 40 dB boost in a separate box. it works but the lack of flatness of the band reject region makes it a pain to use.
I think the distortion in the notch filters in the box can be reduced. We need to confirm its source before going further. I believe the input circuits are clean enough that they are not an issue. Its something with either the analog multipliers or the Jfet switches. The multiplier can be bypassed with the jumper but the open pin needs to be shorted to ground as I remember. I thought I simulated the notch filter in the 1120 but can't find the simulations now. I did find my notch simulations which I can share if you are interested.
I just made available an updated control software for the Boonton. Details here: PC Software control for Analog Audio Analyzers
beginning to learn working with Boonton 1120
@Demian ,
Reading here about the Boonton it seems to me that you know quite a lot about this device.Now I'm just in the process of using this device.
For 1 week ago I was able to buy a 1120.Everything seems to work and it starts up in a normal way.It will do a sweep with the input(Hi) and output (Hi)connected together.
I could do a sweep in this way with the dB unit selected.Now for some reason I'm not able to do this sweep anymore.
I keep getting the error 25 - this says that the start and stop units are not compatible.
At start up or when depressing the LCL/Init key there is 1000Hz and 0.007mV.Which seems to be allright.
Setting the freq / freq - step /the start and stop freq.
Choosing the Dist % and press sweep gives me the error 25.
Maybe you can tell me if I'm pressing the wrong buttons or it is the wrong order.
I am sure that it's something simple or am I wrong ??
Thank you for your reply
Rick
@Demian ,
Reading here about the Boonton it seems to me that you know quite a lot about this device.Now I'm just in the process of using this device.
For 1 week ago I was able to buy a 1120.Everything seems to work and it starts up in a normal way.It will do a sweep with the input(Hi) and output (Hi)connected together.
I could do a sweep in this way with the dB unit selected.Now for some reason I'm not able to do this sweep anymore.
I keep getting the error 25 - this says that the start and stop units are not compatible.
At start up or when depressing the LCL/Init key there is 1000Hz and 0.007mV.Which seems to be allright.
Setting the freq / freq - step /the start and stop freq.
Choosing the Dist % and press sweep gives me the error 25.
Maybe you can tell me if I'm pressing the wrong buttons or it is the wrong order.
I am sure that it's something simple or am I wrong ??
Thank you for your reply
Rick
Rick-
You are most likely entering a voltage when its asking for a frequency or similar. there are specific things you can enter is a particular mode. if frequency either the number or the unit need to be valid. Same for voltage. Do get the manual and study it. I don't use the internal sweep. I got rid of the last plotter I had which would work with it 20? years ago. That's why the software is really helpful.
You are most likely entering a voltage when its asking for a frequency or similar. there are specific things you can enter is a particular mode. if frequency either the number or the unit need to be valid. Same for voltage. Do get the manual and study it. I don't use the internal sweep. I got rid of the last plotter I had which would work with it 20? years ago. That's why the software is really helpful.
Demian ,
Thanks for your answer.Yes , I have the manual and am reading through it.And I am no t trying to plot the result with a plotter.
I am just trying to see how the 1120 is doing the sweep and hwat is changing on the 2 displays.
And then see what result I gives in % distortion.Will see if I can get to do it again ...
Thanks for your answer.Yes , I have the manual and am reading through it.And I am no t trying to plot the result with a plotter.
I am just trying to see how the 1120 is doing the sweep and hwat is changing on the 2 displays.
And then see what result I gives in % distortion.Will see if I can get to do it again ...
I just tried the same thing. First you need to have the analyzer in an appropriate mode with source level and analyzer mode set. If you have a usable reading then after confirming start and stop settings you should be good to go. It seemed to work for me. I'll be exploring whether its a better way to run the automated tests. It looked pretty constrained but maybe I can get more from it.
Now I'm reading through the manual and try to understand what and which settings are correct.When there's nothing connected at the in- and outputs , I see that the analyzer display shows a number 24XXXXX like this and the gate led is flickering on and off. This is Always the same number and the last 2 or 3 digits may change up or down a number.I'm not sure if this is good. I have no experience with this or any other audio analyzer so I'm in the process of learning and to understand this device. When I connect the output to the input I can see the voltage that is set and the standard start frequency of 1000Hz. The program number is 99 in this situation.Although I believe that it is working good I later want to check the different levels. So I downloaded the calibration sheet.But I'm not going to fiddle with that now.
Yes I think it was noise.This happened after I replaced the chassis BNC parts but at the same time , moved them to the front panel. But the hole in the front plate is too big for the chassis parts , so I had to use spacers.Since I couldn't find metal spacers which were not too thick I used plastic spacers instead. But I didn't connect the BNC ground to the device's ground (metal casing).I thought that it wouldn't matter. Now I put a grounding wire to the BNC ground lugs and I don't have this noise anymore. Still reading up on the manual.I have seen some videos on youtube about using the GPIB connector to usb. The results look rather good.I will buy such a GPIB interface and then see how things will go. But that is not right away. Thanks for your answers
Hi, I bought a Boonton 1130 distortion analyzer that works and has an instruction manual. Although it has a complete schematic and parts list with some calibration info, the device is fully operated by a Z80 microprocessor that controls everything inside, such as notch filters, functions an a full set of IEEE-488 bus commands.
The problem is that the manual includes a mixture of some theory of operation and key functions but there no examples of how to make basic measurements. For example, the device has 2 BNC inputs named HI and LO and there is a FLOAT key that seems to switch between balanced and single ended input modes, but there is no explanation on how this really operates. Nothing can be really obtained from studying the schematic as all the switching of the different functions is achieved with FET analog switches managed by the CPU. I am using my old TRIO audio oscillator and I can make some simple frequency and level measurements, but I am confused when it comes to commands.
Is there any other known source of information for learning how to take advantage of this great instrument ? Nothing interesting at the Boonton site that keeps some literature but nothing about on how to really use the instrument.
Any ideas ?
Thank you !
The problem is that the manual includes a mixture of some theory of operation and key functions but there no examples of how to make basic measurements. For example, the device has 2 BNC inputs named HI and LO and there is a FLOAT key that seems to switch between balanced and single ended input modes, but there is no explanation on how this really operates. Nothing can be really obtained from studying the schematic as all the switching of the different functions is achieved with FET analog switches managed by the CPU. I am using my old TRIO audio oscillator and I can make some simple frequency and level measurements, but I am confused when it comes to commands.
Is there any other known source of information for learning how to take advantage of this great instrument ? Nothing interesting at the Boonton site that keeps some literature but nothing about on how to really use the instrument.
Any ideas ?
Thank you !
The 1130 is basically autoranging for any valid input. If the signal is above 50 mv you can get distortion. Level and frequency at almost any level in. The measure selection is the buttons on the left side.
The input is differential. The float button controls shorting the.neg input to ground. The center of the two bncs are the active inputs.
The input is differential. The float button controls shorting the.neg input to ground. The center of the two bncs are the active inputs.
Thank you 1audio, I understand that you have used this instrument before. The manual is very hard to understand for someone that never had the opportunity to see examples on how it should be used. Maybe you could briefly help give some few first steps id I upload the manual PDF.
Boonton 1130 Distortion Analyzer Manual
Also, the 1130 (as the 1121) needs arguments for some commands:
"3-12. Many of the Model 1121A functions have multiple display and entry modes. Listed in Table 3-2, Function Display And Data Entry Units, are the display legends which can be active for each function along with the unit keys in the DATA ENTRY keypad which select the available display modes. Argument entry ranges for all the Model 1130 functions are described in Table 3-3, Valid Function Argument Range. Number entry out of range of the selected functions will result in an error displayed in the SOURCE display window. Errors can be cleared by depressing any key. If at any time prior to entry a wrong digit is entered, depress the CLR key to clear and restore the previous display. "
I will spend some time during the weekend trying to understand and make some measurements. Now I am getting some BNC connectors and assembling some cables and tee connectors so I can hook up generators, oscilloscope, etc.
I will be back to report if I could make it work.
Boonton 1130 Distortion Analyzer Manual
Also, the 1130 (as the 1121) needs arguments for some commands:
"3-12. Many of the Model 1121A functions have multiple display and entry modes. Listed in Table 3-2, Function Display And Data Entry Units, are the display legends which can be active for each function along with the unit keys in the DATA ENTRY keypad which select the available display modes. Argument entry ranges for all the Model 1130 functions are described in Table 3-3, Valid Function Argument Range. Number entry out of range of the selected functions will result in an error displayed in the SOURCE display window. Errors can be cleared by depressing any key. If at any time prior to entry a wrong digit is entered, depress the CLR key to clear and restore the previous display. "
I will spend some time during the weekend trying to understand and make some measurements. Now I am getting some BNC connectors and assembling some cables and tee connectors so I can hook up generators, oscilloscope, etc.
I will be back to report if I could make it work.
There is lots more on the Boontons here: Boonton 1120/1121 Distortion Analyzer tweaks
I have a copy of the manual.
The user interface is typical of 1980's computer controlled stuff. The description of how to use it is not helpful.
Simply put-
1 select what you want to measure (freq, level, distortion, sinad) and it will autorange.
2 if its not autoranging then press the "local" button which resets everything. Then press the float button so the negative input is floating. For the analyzer there are some special options but I rarely use them. Just the filters and the dB if I want the readout in dB.
I modified my three with an extra input monitor out.
We should continue over in the Boonton thread linked above.
I have a copy of the manual.
The user interface is typical of 1980's computer controlled stuff. The description of how to use it is not helpful.
Simply put-
1 select what you want to measure (freq, level, distortion, sinad) and it will autorange.
2 if its not autoranging then press the "local" button which resets everything. Then press the float button so the negative input is floating. For the analyzer there are some special options but I rarely use them. Just the filters and the dB if I want the readout in dB.
I modified my three with an extra input monitor out.
We should continue over in the Boonton thread linked above.
@Obiwan -- I first got a Boonton over a decade ago -- before the manual was readily available. Fortunately, Boonton is in NJ and they were able to get it up and running by replacing all of the filter caps -- these are prone to failure arising from heat within the cabinet. I was very lucky to strike up a conversation with the tech who repaired the unit and he helped with some of the details and he mentioned that failure in the power supply, low voltages was a primary culprit. A lot of the Boonton units were sold to the military.
Demian got some of the spare boards I had. The unit was sold when I got an AP.
Demian got some of the spare boards I had. The unit was sold when I got an AP.
New to the Boontons
Hi Demian,
I recent acquired two 'similar' Boonton units. Many questions.
The first is an 1120/S10 which works; and after a 30 minute warmup gives a loopback reading of 0.0022% distortion at 30kHz. BW
I also have an 1121-11-12 which shows: Error 34,33,32,31,30 -> Error 31. The power supplies, and main motherboards, and output boards on the rear - appear to be identical in both sets. Both have the power transformers on the right looking at the rear, and the 323K regulator nearest the right side, I believe that was the later, later version of the 1120 and 1121.
The 5 big caps on the 1120 PS are 4700/35v with screws, while on the 1121 PS they are 6800/50v soldered in. All appear to have low ESR readings. The last two big caps on the PS board 2200/35v and 4700/16v look cheap, and I replaced them with new parts in both units: 4700/35v and 6800/16v, there is also a 100/25v that I will change to 330/25v when I find the bag.
On the 1121, setting the Source Level to 3.0 V, the Analyzer reads only several random 'mV' on the Analyzer display, so the signal is getting lost (might be an open cap or bad relay?).
The Manual for the 1121A gives suggestions for that range of errors as failure of part or parts on the A6 board. Since the A6 boards in both units have the same Assembly numbers I put the 1121 A6 into the functioning 1120/S10 and it worked giving 0.0027% after 30 min warmup.
From reading this thread, seems this Error could be from very low 5.0 volt line too. Where do people measure the voltages in these sets?
I fully plan to try some of the later IC's, LT1468 (don't forget - lift pin #8) and LT1469 (no lifting any pins, not quite as tuned) or maybe the OPA1611A (single), and OPA1612A (dual) which are rated for 0.000015% Distortion, and high output currents, they replace the now discontinued LME49710, 20, 22, etc., parts.
As for other parts changes, I get confused about which board is being modded, when you leave off the A? And just say 'U8' or 'U10', or R42...
I note that there are 10k resistors that look like 1 watt parts, these are carbon composition parts, which can both drift in value, and also become noisy over time, I think it was suggested to change them to 3 watt bulbs, why not try lower noise 1% or 0.1% metal film 10k resistors? I have some 10k parts, that look like small Corning power resistors that probably can sink 3 Watts and are within 5 ohms of each other or better.
Those 56 uf tant caps, which might be a 56uF and a 15uF that are back to back in the signal path, would that make it 12uF, or is that a factory error?
Those could be replaced by bipolar electro's but what would be better - 33uF at 100 volts, or 220uF at 16 volts? I have read higher voltage Electro's have better sound and lower distortion???
Neither of my sets has deformed or bent metal. I already hit those 1121 boards with a hammer to make sure they are well inserted into the bottom of the mainboard, the board 'keys' were all removed, but, I found one scrunched up under one of the boards in the slot, took it out... Still getting the Error 34 -30 Errors.
Any other suggestions welcome!
Steven
Hi Demian,
I recent acquired two 'similar' Boonton units. Many questions.
The first is an 1120/S10 which works; and after a 30 minute warmup gives a loopback reading of 0.0022% distortion at 30kHz. BW
I also have an 1121-11-12 which shows: Error 34,33,32,31,30 -> Error 31. The power supplies, and main motherboards, and output boards on the rear - appear to be identical in both sets. Both have the power transformers on the right looking at the rear, and the 323K regulator nearest the right side, I believe that was the later, later version of the 1120 and 1121.
The 5 big caps on the 1120 PS are 4700/35v with screws, while on the 1121 PS they are 6800/50v soldered in. All appear to have low ESR readings. The last two big caps on the PS board 2200/35v and 4700/16v look cheap, and I replaced them with new parts in both units: 4700/35v and 6800/16v, there is also a 100/25v that I will change to 330/25v when I find the bag.
On the 1121, setting the Source Level to 3.0 V, the Analyzer reads only several random 'mV' on the Analyzer display, so the signal is getting lost (might be an open cap or bad relay?).
The Manual for the 1121A gives suggestions for that range of errors as failure of part or parts on the A6 board. Since the A6 boards in both units have the same Assembly numbers I put the 1121 A6 into the functioning 1120/S10 and it worked giving 0.0027% after 30 min warmup.
From reading this thread, seems this Error could be from very low 5.0 volt line too. Where do people measure the voltages in these sets?
I fully plan to try some of the later IC's, LT1468 (don't forget - lift pin #8) and LT1469 (no lifting any pins, not quite as tuned) or maybe the OPA1611A (single), and OPA1612A (dual) which are rated for 0.000015% Distortion, and high output currents, they replace the now discontinued LME49710, 20, 22, etc., parts.
As for other parts changes, I get confused about which board is being modded, when you leave off the A? And just say 'U8' or 'U10', or R42...
I note that there are 10k resistors that look like 1 watt parts, these are carbon composition parts, which can both drift in value, and also become noisy over time, I think it was suggested to change them to 3 watt bulbs, why not try lower noise 1% or 0.1% metal film 10k resistors? I have some 10k parts, that look like small Corning power resistors that probably can sink 3 Watts and are within 5 ohms of each other or better.
Those 56 uf tant caps, which might be a 56uF and a 15uF that are back to back in the signal path, would that make it 12uF, or is that a factory error?
Those could be replaced by bipolar electro's but what would be better - 33uF at 100 volts, or 220uF at 16 volts? I have read higher voltage Electro's have better sound and lower distortion???
Neither of my sets has deformed or bent metal. I already hit those 1121 boards with a hammer to make sure they are well inserted into the bottom of the mainboard, the board 'keys' were all removed, but, I found one scrunched up under one of the boards in the slot, took it out... Still getting the Error 34 -30 Errors.
Any other suggestions welcome!
Steven
The two units you have are almost the same. A few minor hardware differences and some software tweaks are the key differences. The errors you see are because the bad board is not tuning correctly. Hardest to troubleshoot are the optios. I just replaced all of them on the one I had with a problem. More likely in your case is a dead fet in the tuning circuit.
Once you have them running I can forward Mike Lynch's upgrade directions which are quite involved. They do make a difference.
While the boards are interchangeable they do not work quite the same. The 1121 has a more sophisticated tuning in the notch circuit and another difference on the input board which escapes me.
PM me if you need more help. Mike can also be helpful but it seems he is buried in work these days.
Once you have them running I can forward Mike Lynch's upgrade directions which are quite involved. They do make a difference.
While the boards are interchangeable they do not work quite the same. The 1121 has a more sophisticated tuning in the notch circuit and another difference on the input board which escapes me.
PM me if you need more help. Mike can also be helpful but it seems he is buried in work these days.