matta
Well-known member
Hey Guys,
Going to be honest here and say although I have owned a scope for a couple years now I have very rarely put it to use, sad, but true...
I understand how to operate its basic functions and can take basic measurements. It is an oldy, but a goody, a Tektronix 422, Dual Trace. I had it calibrated some time back by the local Tek agents and they found it to be in great condition and tuned up where needed.
I don't however own a signal generator, partly my lack of using it, so I bought an app for my iPhone called Sig Gen, with the volume set to full the amplitude should measure the same, so 2Vpp in the app should ready 2Vpp on the scope... it doesn't, I had to attenuate to 1.74Vpp to have it read 2Vpp on the scope, wrote to the software house and looking into it..
EDIT: Got this response from the developers:
It however get me thinking... MOST hardware signal generators are unbalanced right? Most have BNC outs, so a shield and a signal wire? How does this effect us in the studio 'balanced' world. If at all?
For example you will see in most service notes something along the lines of "Apply a 1kHz tone at 1Vpp to the input"... what happens if that input it balanced, for example, a mic pre? Do you then apply the signal on Pin2 and tie Pins 1+ 3 together? How does it differ from unbalanced devices?
On the topic of signal/function generators, are there any good/decent/inexpensive yet fairly accurate hardware units around that anyone can recommend, even if they are older ones, there is little to no used market here but I'll be going to the UK next year and may be able to pick up something there. Is it worth getting one? Are they any better than software ones?
Thanks in advance
Matt
Going to be honest here and say although I have owned a scope for a couple years now I have very rarely put it to use, sad, but true...
I understand how to operate its basic functions and can take basic measurements. It is an oldy, but a goody, a Tektronix 422, Dual Trace. I had it calibrated some time back by the local Tek agents and they found it to be in great condition and tuned up where needed.
I don't however own a signal generator, partly my lack of using it, so I bought an app for my iPhone called Sig Gen, with the volume set to full the amplitude should measure the same, so 2Vpp in the app should ready 2Vpp on the scope... it doesn't, I had to attenuate to 1.74Vpp to have it read 2Vpp on the scope, wrote to the software house and looking into it..
EDIT: Got this response from the developers:
The amplitude in the app is really a "best guess", but you're using it correctly. It may vary from device to device. Since this is an audio port a 15% error is not meaningful, so I doubt the amplifier circuit is spec'd very tightly. It may also not be especially linear. Also the load can influence the amplitude, obviously.
It however get me thinking... MOST hardware signal generators are unbalanced right? Most have BNC outs, so a shield and a signal wire? How does this effect us in the studio 'balanced' world. If at all?
For example you will see in most service notes something along the lines of "Apply a 1kHz tone at 1Vpp to the input"... what happens if that input it balanced, for example, a mic pre? Do you then apply the signal on Pin2 and tie Pins 1+ 3 together? How does it differ from unbalanced devices?
On the topic of signal/function generators, are there any good/decent/inexpensive yet fairly accurate hardware units around that anyone can recommend, even if they are older ones, there is little to no used market here but I'll be going to the UK next year and may be able to pick up something there. Is it worth getting one? Are they any better than software ones?
Thanks in advance
Matt