Products > Test Equipment
Test Equipment Anonymous (TEA) group therapy thread
bd139:
I'd swap them out for BNC. Bear in mind output of that is probably 75 ohms.
I'd grab or make a minimum loss pad to get it down to 50. Lose about 6dB but worth it for compatibility with everything else which is pretty much 50 ohms. See: https://www.maximintegrated.com/en/app-notes/index.mvp/id/972
Specmaster:
Yes it is 75 ohms output impedance and as you rightly say, almost everything else is 50 ohms. How does the Leader fare in that dept as it uses banana sockets?
bd139:
It has wild and unpredictable output impedance. They are usually loosely coupled for signal injection rather than calibrated output. I am considering modifying it shortly to add a buffer (TIA) which will give a predictable 50 ohm output. However not sure I’ll need that. Most of the time it will be whacked in the antenna hole and used to adjust double tuned circuits by ear. Nothing particularly critical.
Specmaster:
So, have I got this round the right way, if I swap out the sockets for BNC ones, to effect the MLP's, I connect the lead that is currently going to the centre pin of the co-ax socket to the centre connection of the BNC via a 43ohm resistor and also from that some pin I take a 86 or 87 ohm resistor to ground and I do that twice, once on the RF output socket and again on the sweep socket for scope? I doubt I'll ever need the Ext input connection so I'll leave that alone, but if I was make that into a BNC, just do the same again or reverse the resistors as its more likely to be coming from a 50 ohm in to a 75 ohm input impedance?
bd139:
I’d stuff a 75 ohm BNC on the generator straight up and build the pad inside a Pomona box you plug into it. Then when you get something else 75 ohm it’ll be useable as well.
I’d ony do this to the RF out.
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