I came across a B&K 1471 dual trace scope and a HP freq counter, $75 for both. He says they both work like new. Is this worth checking out, theres not much info out there on the B&K, and I don't know what a frequency counter is yet, lol. He didn't yet state the model # of the feq counter.
Thanks
John
Thanks
John
Last edited:
I'm still awaiting a response on the model number of the frequency counter.
Unfortunately, I know no one that can help me out on the scope. Is there anything I should look for? What does the average audio electronics hobbyist look for/need in a scope?
A regular 20 MHz scope will be fine for audio (and slower micro controller debugging) use. Beyond that is icing on the cake.
When you turn on the scope, ground the input (using the ground switch) and verify that the intensity and focus knobs work. You should be able to tweak the intensity of the displayed trace from complete dark to burn-out bright and you should be able to focus the trace into a crisp line.
When turning the time/div knob you should be able to get the time scale slow/long enough that the trace turns into a slowly moving dot that moves from left to right. Usually the slowest time base will make the dot move across the screen in about five seconds. Turning the time/div knob the other way will cause the dot to move so fast that it forms a trace on the scope screen.
Vertical adjustment knobs should move the trace up/down. Horizontal adjustments should move the trace left/right.
The scope should come with probes. Attach a probe to one of the inputs and DC couple the input. Attach the probe to the CAL output of the scope (if it has one). It should say by the CAL output (typically a little eye or test point on the front of the scope) what signal levels and frequency to expect. Verify that you get the right signal level and frequency. The CAL signal is typically a square wave and should show as a clean square wave trace. If the corners of the square wave are 'pointy' or rounded off that means the probe needs to be calibrated (simple DIY job using a plastic trimmer tool on the tuning capacitor in the probe head - see the manual for the probe or o'scope).
If you're completely new to oscilloscopes, I suggest looking at an online tutorial before you meet with the seller.
A frequency counter can be handy. If nothing else, then because it usually contains a precision frequency reference. In some cases this reference oscillator is temperature controlled - hence, drift very little over time. However, the accuracy of the frequency measurements will depend on the accuracy of this reference. If at all possible, I would get that reference calibrated against a known frequency.
~Tom
When you turn on the scope, ground the input (using the ground switch) and verify that the intensity and focus knobs work. You should be able to tweak the intensity of the displayed trace from complete dark to burn-out bright and you should be able to focus the trace into a crisp line.
When turning the time/div knob you should be able to get the time scale slow/long enough that the trace turns into a slowly moving dot that moves from left to right. Usually the slowest time base will make the dot move across the screen in about five seconds. Turning the time/div knob the other way will cause the dot to move so fast that it forms a trace on the scope screen.
Vertical adjustment knobs should move the trace up/down. Horizontal adjustments should move the trace left/right.
The scope should come with probes. Attach a probe to one of the inputs and DC couple the input. Attach the probe to the CAL output of the scope (if it has one). It should say by the CAL output (typically a little eye or test point on the front of the scope) what signal levels and frequency to expect. Verify that you get the right signal level and frequency. The CAL signal is typically a square wave and should show as a clean square wave trace. If the corners of the square wave are 'pointy' or rounded off that means the probe needs to be calibrated (simple DIY job using a plastic trimmer tool on the tuning capacitor in the probe head - see the manual for the probe or o'scope).
If you're completely new to oscilloscopes, I suggest looking at an online tutorial before you meet with the seller.
A frequency counter can be handy. If nothing else, then because it usually contains a precision frequency reference. In some cases this reference oscillator is temperature controlled - hence, drift very little over time. However, the accuracy of the frequency measurements will depend on the accuracy of this reference. If at all possible, I would get that reference calibrated against a known frequency.
~Tom
'Scope Checkout
ANY working 'scope is at least 100 times better than NO 'scope.
The instrument probably has an internal signal for probe compensation and rough calibration - usually a squarewave at 1 KHz or 10 KHz, and a particular amplitude somewhere between 1V and 10V pk-pk. Use a 10X probe to view this signal. Adjust "Focus" and "Brightness" to get a usable trace. Set position controls, vertical sensitivity, horizontal sweep rate, and trigger controls to get an on-screen display.
On the probe body, or probe connector, you will find an adjustment to optimize the frequency response of the probe as connected to that particular 'scope channel. Adjust it for the best squarewave display. (The atch image of a 'scope display illustrates a typical range of adjustments.)
You should see a stable, crisp, well-defined trace - without "fuzz" (either noisy vertical amplifiers, or problems in the display circuits), and without ripple (power supply problems, such as worn out electrolytic capacitors, or an EMI/RFI problem). If there is significant horizontal jitter there may be problems with the trigger circuits.
You should be able to get a readable display for 3 or 4 different settings of vertical and horizontal sensitivities. The displayed amplitudes and periods should track reasonably well from setting to setting. (The absolute accuracy of a 'scope isn't fabulous - seldom any better than 5% - but the range-to-range tracking of vertical and horizontal settings should be better than that.)
Repeat these test for both vertical channels if it's a dual-trace instrument.
If the instrument has additional features, like delayed-sweep, trace arithmetic, X-Y display mode, etc, you can do a quick check of their basic functionality. Depending on your particular interests, these features may or may not be useful.
In my opinion, the biggest practical difference between the really good 'scopes and the rest of the pack is in the triggering system. I don't know of any particular test to evaluate this function - it's something that you develop a "feel" for, especially as you work with complex waveforms. Every genuine Tek 'scope I've used for nearly half a century has had stable, effective, triggering functions that were compatible with the instrument's basic capabilities. 'Scopes from other manufacturers have also had good triggering performance, but not as consistent from model to model as the Tek products.
Dale
ANY working 'scope is at least 100 times better than NO 'scope.
The instrument probably has an internal signal for probe compensation and rough calibration - usually a squarewave at 1 KHz or 10 KHz, and a particular amplitude somewhere between 1V and 10V pk-pk. Use a 10X probe to view this signal. Adjust "Focus" and "Brightness" to get a usable trace. Set position controls, vertical sensitivity, horizontal sweep rate, and trigger controls to get an on-screen display.
On the probe body, or probe connector, you will find an adjustment to optimize the frequency response of the probe as connected to that particular 'scope channel. Adjust it for the best squarewave display. (The atch image of a 'scope display illustrates a typical range of adjustments.)
You should see a stable, crisp, well-defined trace - without "fuzz" (either noisy vertical amplifiers, or problems in the display circuits), and without ripple (power supply problems, such as worn out electrolytic capacitors, or an EMI/RFI problem). If there is significant horizontal jitter there may be problems with the trigger circuits.
You should be able to get a readable display for 3 or 4 different settings of vertical and horizontal sensitivities. The displayed amplitudes and periods should track reasonably well from setting to setting. (The absolute accuracy of a 'scope isn't fabulous - seldom any better than 5% - but the range-to-range tracking of vertical and horizontal settings should be better than that.)
Repeat these test for both vertical channels if it's a dual-trace instrument.
If the instrument has additional features, like delayed-sweep, trace arithmetic, X-Y display mode, etc, you can do a quick check of their basic functionality. Depending on your particular interests, these features may or may not be useful.
In my opinion, the biggest practical difference between the really good 'scopes and the rest of the pack is in the triggering system. I don't know of any particular test to evaluate this function - it's something that you develop a "feel" for, especially as you work with complex waveforms. Every genuine Tek 'scope I've used for nearly half a century has had stable, effective, triggering functions that were compatible with the instrument's basic capabilities. 'Scopes from other manufacturers have also had good triggering performance, but not as consistent from model to model as the Tek products.
Dale
Attachments
I've got a B&K scope- not the same model- and it's been a simple and reliable tool for me.
If it has:
Probe or better- probes
Manual
and is working....
$75 seems very reasonable, IMO.
The seller should be willing to demo if he states they are working 'as new'.
The HP freq counter is an 'extra' and you can always re-sell it if you don't need it...as long as it is working.
I looked at the B&K website and apparently you can request manuals for older equipment.
If it has:
Probe or better- probes
Manual
and is working....
$75 seems very reasonable, IMO.
The seller should be willing to demo if he states they are working 'as new'.
The HP freq counter is an 'extra' and you can always re-sell it if you don't need it...as long as it is working.
I looked at the B&K website and apparently you can request manuals for older equipment.
Thanks so much for taking the time for the info, that youtube vid helped a lot. I might actually be able to use one of these now.
He just emailed back and lowered it to $50 for both. I think that sounds great. I'm gonna look at it tonite if possible.
The freq counter is a HP model 5245L. I don't think anyone will buy it unless I get really lucky but hey, an added bonus!
These are both dinosaurs, but should work well in my environment.
He just emailed back and lowered it to $50 for both. I think that sounds great. I'm gonna look at it tonite if possible.
The freq counter is a HP model 5245L. I don't think anyone will buy it unless I get really lucky but hey, an added bonus!
These are both dinosaurs, but should work well in my environment.
If the 'scope is functional, $50 sounds like a fair price - especially if it has a probe or two.
Speaking for us dinosaurs . . . the only bad things about the 5245L are the physical size, and the requirement for AC power. As already mentioned, the Nixie tube display definitely has a mad-scientist mystique. In some circles the Nixie display assembly has value all by itself. The 5245L was already obsolete when I was using them 30 years ago - but the mainframes were reliable performers. (The heterodyne downconverter plug-ins that extended the counter range into microwave bands were another story.) I think some of the 5245L's had a high-precision timebase oscillator, but even the standard timebase might be the most accurate frequency standard you're likely to have in your workshop.
Dale
He just got back with me, it's a 10mhz scope and no probes, just a homemead RCA connector. It seems, as stated above, that 20mhz is a good starting point. Is this still useful?
I'm still trying to figure out what exactly a mhz means on a scope.
Edit: OK, now that I know human hearing goes up to 20kHZ, this scope only covers the lower half of that....since I often have problems at higher frequencies with what few amps I've built, would this be useful to me in my limited space of a hobby room?
I'm still trying to figure out what exactly a mhz means on a scope.
Edit: OK, now that I know human hearing goes up to 20kHZ, this scope only covers the lower half of that....since I often have problems at higher frequencies with what few amps I've built, would this be useful to me in my limited space of a hobby room?
Last edited:
10mHz will be fine for your audio projects.
You can do a lot of work with wire and alligator clips; pick up a cheap probe on 'the bay' later.
Buy it or it will be gone...
m=million
k=thousand
Not for being a stickler and not to offend anybody, but just to get things (upper case and lower case) right, which is important IMHO:
m = milli (1/1000)
M = Mega, 1.000.000 (million)
k = 1000 (thousand)
An example: 10 mHz is 10 milli-Herz and not 10 million Herz.
Karsten
Last edited:
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.