All
Thanks for all the suggestions. And yes, I could buy a 20dB attenuator for a few dollars but there is little to learn in doing that ![Cheesy :D](https://www.eevblog.com/forum/Smileys/default/xcheesy.gif.pagespeed.ic.KPzuH4J-TG.png)
One thing that I have noticed is that members prefer SMA to BNC. Can anyone explain this given that most test gear is fitted with BNC?
enut11
PS
At the moment the max I can test at is 50MHz and even that is probably a little dodgy. Any suggestions for an affordable 500MHz or 1GHz generator?
Because SMA is a better connector in a lot of ways and is very common everywhere.
The BNC connector while very common has some issues. While it is very easy to plug in (No need to screw it on all the way) it does suffer in terms of RF performance and is physically pretty large. Have a look at RF test equipment and try to find a BNC on there, you won't. What you find there is N connectors or sometimes APC7 connectors (Mostly only on network analyzers) because of there much superior RF performance. Any BNCs you find on RF test gear is for slow low bandwidth signals like modulation, leveling control, gating, trigger etc..
In general typical BNC starts having problems once you approach 1GHz, fancy good quality BNCs go higher into a few GHz but you also need the nice high quality connector on the cable too. While the N connector has no problems with GHz and good ones go to 20GHz and up. Only problem is that N is twice the size of BNC so soldering N connectors on your deadbug style prototype circuit is not convenient at all. However there is also the popular SMA connector, featuring a size significantly smaller than BNC while offering good RF performance to 4GHz for the cheap ones while higher performance variants like the 3.5mm or 2.5mm go beyond 20GHz in the identical form factor (Even SMA compatible, but please be nice to fancy RF connectors). You can buy a bunch of cheep board mount SMA connectors and just solder then into your circuit whenever needed, treat them as disposable.
Have a look at one of the biggest manufacturers of RF modules:
https://www.minicircuits.com/ Most of there modules are SMA because its such a convenient connector that provides great RF performance in a small form factor.
But... my <insert testgear here> only has BNC!
Well.. so? What does it matter? You do need a cable to hook it up to something anyway. So you just get a cable that is BNC on one end and SMA on the other. Any place that sells RF cables will have such cables. Or if you want to DIY it you can just cut up a BNC cable in half and put SMA connectors on the end yourself. So i just keep a bunch of BNC to SMA and N to SMA cables and a box full of cheep various kinds of board mount SMAs.
If you want cheap cables but want it a bit more legit than a random ebay seller this is a good Chinese company:
https://www.rfsupplier.com They have every possible RF connector and will make any kind of custom RF cable for you even in small quantities.
As for a RF generator, used market like ebay is the best choice to pick up an old boatanchor that goes to a few GHz (Tho australia might be tricky)
Also if you are just getting into RF maybe you might find the NanoVNA very useful:
http://nanovna.com/ Its a $50 network analyzer to 900 MHz (Tho best performance is only up to 300MHz). This lets you characterize your RF blocks properly across frequency and show you things like phase and return loss.