Wenzel Low Frequency Circulator

[uofmrob]

And maybe one that could give me the half watt output that I would need.

[lowimpedance]

Just a thought, what about using an sot to dip adapter which would make it more robust as the LT1395 is soldered to the adapter then you have rigid pins on the other side to solder other parts to.

for example;
https://www.mouser.com/Embedded-Solutions/Engineering-Tools/Embedded-Tools-Accessories/Sockets-Adapters/_/N-cxdjj?Keyword=sot+to+dip+adapter&FS=True

see digikey for more etc.

[uofmrob]

Thanks for the advice! I have some of these, but the consensus seemed to be that pass and adapters aren't the way to go.

https://www.adafruit.com/product/1210

[uofmrob]

Hey everyone, that's for all the advice! I have a working circulator! There's no leakage at all. It passes reflections on with the exact signal voltage and if you put a 50 Ohm terminator in, everything down wind sees nothing. Thanks so much for all the help! Now in to designing a coil!

[KE5FX]

Awesome, good going!  That's a perfectly reasonable way to do it as long as the IC adapter doesn't add a lot of stray capacitance. 

[uofmrob]

I was having so much trouble with the fragility of the surface mount leads, I just decided to give this a whirl to see if it worked. This quad op amp is pretty low power on the specs (it's one that I had bought initially as a spec replacement for the one in the original paper). I'll probably have to swap out the IC for something that can put out more power, but I'll give this a shot first. At least I know I can get one to work!

[uofmrob]

One more question. Is there a reason that it wouldn't be safe to test this out with an oscilloscope in 1 MOhm mode? I was looking at the signal and my scope is acting funny now (it's a Tektronix 2430 scope). Did I bork my scope? 

[uofmrob]

I checked and there are no shorts to ground or anything. It wouldn't be too surprising that my scope is dying just from being 30 some years old. But I certainly don't want to be doing something I shouldn't. I had a 20 MHz 2 Vpp sine wave on my function generator on port 1 and had a BNC cable running from port 3 to the scope and I was testing the effect of a 50 Ohm load on port 2. It works perfectly. Without the load on port 2, the signal gets reflected to port 3, but when you put the load in, the signal goes away completely.

[uofmrob]

The only thing I can think of is that I was counting on the source providing the ground. I had forgotten that and there was a point that I didn't have the source plugged in, but the scope was still connected. Without the ground from the source, there is a couple hundred millivolts between the ground plane of the circulator and the ground of the scope. That might have been the classic blowing up there scope through a current through the ground. Ugh, I should have grounded the circuit.

[KE5FX]

Vanishingly unlikely that you damaged the scope with this circuit.  What is the scope actually doing? 

If you take it apart for troubleshooting, remember to use a fan on the heat sinks.  Failure to do that will hose a 2430.

[uofmrob]

It already had an issue with the relay on the 500mV/1V division on channel 2 not triggering on the high voltage side. Now it's not able to get a consistent trigger on any signal on either channel. You can see the signal, but it's completely unstable in the time domain.

[uofmrob]

I thought it was maybe the function generator putting out an unstable signal (it's a FeelElec FY6900 60 MHz AWG), but my analog scope locks onto its signal up to its bandwidth limit just fine.

[uofmrob]

Hi everyone,
I realized that I forgot to send a final thank you to everyone for all the help. I got it working perfectly!
Rob

[uofmrob]

Also, the scope is OK. My 4-year-old had messed with the knobs while I wasn't looking and had changed the horizontal scaling so much that it was seeming to have a signal that it couldn't lock on, but it was interpolating and when I went back to a proper scaling, it triggered fine.

[SilverSolder]

Also, the scope is OK. My 4-year-old had messed with the knobs while I wasn't looking and had changed the horizontal scaling so much that it was seeming to have a signal that it couldn't lock on, but it was interpolating and when I went back to a proper scaling, it triggered fine.

One of the unexpected dangers of having children!