Electronics > RF, Microwave, Ham Radio

New lab: Oscilloscope bandwidth

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jnicholls:
Hi all, first post here.

I'm building for the first time my very own electronics lab. I am both a ham and an antenna engineer, so I have a decent amount of theoretical experience in electronics. Now I want to go hands-on.  I plan on starting with some basic electronics projects then moving into the building of radios. My goal is to quickly get up to VHF/UHF so I can potentially start playing around with satellites.

My first big decision is what oscilloscope to get. A lot of people on this forum say to just go for a Rigol 1054Z as an entry level scope. I am also considering the Rigol 2072a as I can get it for not too much more than the 1054z (only about $100-200 more). The 1054z "hacked" is 100 MHz while the 2072 "hacked" is 300 MHz. My question is really whether I can just get away with the 100 MHz bandwidth of the 1054z or if I should get the 2072a right off the bat since it has 300 MHz bandwidth. I really have no idea if that extra bandwidth will come in handy or not.

I also am not sure if I will need the 4 channels vs. 2, although more always seems better.

What would you guys recommend based on my goals and interests? Is a higher bandwidth scope necessary or even just high priority? I'll definitely be getting a spectrum analyzer at some point, although that might not happen for a little while until I save up more money.

Thanks in advance.

Mosaic:
UHF/VHF....bandwidth for instruments is what is required.

Ideally you need a spectrum analyzer, a VNA($$$) and SOL cal kit, an precision RF power meter, the ability to fab and build FR4 SMT boards. A good capacitance/inductance meter that gives Q and ESR and so forth. Signal generator good to the frq of interest. Freq. counter also good to the frq of interest. Optionally a disciplined GPS 10Mhz ref.
Then bits an pieces such as assorted N, SMA, BNC, F connectors and adaptors. RG 58, RG400 cabling and crimp type connectors and a matched die crimper. For longer antenna line runs look at LMR 400 with N connector ends. Then Couplers, mixers, splitters, attenuators and such like. Also have a look at SDR radio options. Checkout the EMRFD yahoo forum.
Have a look at this youtube channel
https://www.youtube.com/channel/UCiqd3GLTluk2s_IBt7p_LjA

As it happens I just did this over the last few months.
I use a Rigol DSA 815 TG  with all options and  I just discovered it's got some nonlinearity bumps in the recvr that have to be cal'd out manually.
So I used my HP8753D VNA as a CW signal source, my Boonton 4210-4B precision RF power meter to map the VNA  signal amplitudes to 1.5Ghz (the SA max frq) . Enter that cal table into the SA, then sweep the SA slowly with the VNA in manual sweep mode...observe the interpolation and add more cal points to iron out the bumps. Finally got it down to around 0.1dB flatness full range, which is 8x better than the OEM spec.

 

Wuerstchenhund:

--- Quote from: jnicholls on March 10, 2016, 05:33:22 am ---My first big decision is what oscilloscope to get. A lot of people on this forum say to just go for a Rigol 1054Z as an entry level scope. I am also considering the Rigol 2072a as I can get it for not too much more than the 1054z (only about $100-200 more). The 1054z "hacked" is 100 MHz while the 2072 "hacked" is 300 MHz. My question is really whether I can just get away with the 100 MHz bandwidth of the 1054z or if I should get the 2072a right off the bat since it has 300 MHz bandwidth. I really have no idea if that extra bandwidth will come in handy or not.

--- End quote ---

You're asking in the wrong forum. This forum is for RF related stuff, you should really ask in the Test Instruments subforum.

tggzzz:

--- Quote from: Wuerstchenhund on March 18, 2016, 06:10:15 am ---You're asking in the wrong forum. This forum is for RF related stuff, you should really ask in the Test Instruments subforum.

--- End quote ---

He's doing "building of radios. My goal is to quickly get up to VHF/UHF" and want to know about instruments for that. This is an equally reasonable forum.

Don't think of an oscilloscope as a substitute for RF test equipment, unless you have an insanely high bandwidth and sampling rate.

Have a look at the attachments to the first posts in https://www.eevblog.com/forum/projects/project-yaigol-fixing-rigol-scope-design-problems/

Howardlong:
A radio/communications test set is at least as valuable as a scope when debugging VHF/UHF, they include an RF signal generator, power measurement, frequency counter, a sensitivity check and often much more.

Some comms test sets have a scope, but they're typically single channel and very low bandwidth, Ok for checking a few voltages and a sanity check on audio frequencies, but anything more and you need a proper scope.

Why is a scope of limited use for RF? While it's certainly a near essential piece of test gear, generally they will lack the sensitivity and bandwidth required, but perhaps more importantly they lack the filtering afforded by purpose designed RF tools. You wouldn't use a scope for testing band limited signal to noise for example, although I'm sure someone will come up and tell me a contrived way of doing it with a scope!

I would get a comms test set and scope before investing in a VNA or SA for VHF and UHF circuits. Instead of an SA, and SDR can be an invaluable bit of test equipment for tracing receivers: SAs tend to be much less sensitive than SDRs. An SA on the other hand is probably more useful than an SDR for tracing transmitters as you really need wide spans to measure harmonics and IMD products. Some comms test sets already have spectrum analysers built in, by the way.

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