In order to measure transceiver circuits up to 50MHz , what is the minium bandwidth of an oscope needed.
I have read that you should get one that has a BW of five times the frequency of the circuit under test. If that is so then it's way out of my budget envelope,but a 50 MHz one is not.

 

You have read well. To be able to view a signal on the scope accurately you need a scope with at least 5 times the measured signal bandwidth. If you use a 50MHz scope to measure a 50MHz signal, you will see its amplitude/sqrt(2) on the scope and it will be phase shifted too.

 

Hello,

If the oscilloscope has a bandwidth of 50 Mhz, they mean that it is the - 3 dB point of the scope.
Read the XYZ of oscilloscopes for more info.

Bertus

 

Bertus, your depth of knowledge and ability to link valuable info never ceases to amaze me. I can only aspire to one day have the depth you exhibit on a daily basis. Thanks!!!
Bob

 

Thanks for the info gentlemen, but alas I am still confused (an old dog finding it hard to learn new tricks).

I am finding differing opinions on the subject i.e.-

5-10 times the f under test for Digital circuits.
2-3 times for Analog.

As I have bought a Rigol DS1052E (50 MHz) for $400 new, and I would dearly love it if 2 times for Analog was correct. I will be building QRP gear up to 17M from Ham produced kits. Iam a new Ham,but not entirely new to electronics -serving in the USAF as a Radio/and Nav Aids Tech way back when solid state was just taking over (57-66).

The above scope can be hacked to 100 MHz if you get the one with the old Firmware,saving $300. See EVV blog site episode #70. Please delete that if not acceptable.

 

Thanks for the info gentlemen, but alas I am still confused (an old dog finding it hard to learn new tricks).

I am finding differing opinions on the subject i.e.-

5-10 times the f under test for Digital circuits.
2-3 times for Analog.

As I have bought a Rigol DS1052E (50 MHz) for $400 new, and I would dearly love it if 2 times for Analog was correct. I will be building QRP gear up to 17M from Ham produced kits. Iam a new Ham,but not entirely new to electronics -serving in the USAF as a Radio/and Nav Aids Tech way back when solid state was just taking over (57-66).

The above scope can be hacked to 100 MHz if you get the one with the old Firmware,saving $300. See EVV blog site episode #70. Please delete that if not acceptable.

Digital signals need more bandwidth in order to capture their fast rising/falling edges accurately. Analog signals have slower rising/falling times and thus they need less bandwidth to be captured with acceptable accuracy.