Wenzel Circulator Isolator

[longh]

Hey All,

Came across this awesome circuit designed by Charles Wenzel of TechLib fame (one of my favorite websites): http://techlib.com/files/RFDesign3.pdf

It is an "RF Circulator/Isolator" made using just 3 op-amps, that works from ~200MHz down to DC! (A DC circulator still seems weird to me).

Anyway I wanted to build a few, and put them in a nice die cast enclosure. I also wanted to make a DC-DC section that generates the +-12V rail for the op amps from a standard 5V input (like a USB battery pack). I recently got a CNC milling machine and thought milling the ports in a Hammond enclosure would be a good project.

I wanted to gauge interest to see if this is something I could sell. I'm trying to get started in making electronics products and selling them on the side, just a small hobby. Is anyone interested in buying one of these/ how much would you pay for it?

Thanks,
-Hunter
KJ4YQP

[KE5FX]

Be sure to check out the earlier thread on this, if you haven't already.

[LaserSteve]

This Nerd would be in at 200 Mhz, reasonably flat response,  and less then 200$. He'd be in for another 100$ if you can get to 15 db isolation at DC  to 500 Mhz, at -7 dbm levels.  At that price I'd like a case and a power on LED.  Bonus points for a switchable  limiter to protect  my SA on port three.

I just do not have much time to build any more, and have drooled over that drawing for years.

Steve

[longh]

Nice, I hadn't seen that earlier thread. A lot of good info!

Also the wish list is very helpful. Do you all think BNC ports or SMA ports would be preferable? I was envisioning having board edge mounted, surface mount, SMA ports. But I can't figure out how they would go through the case without having to be soldered in after the PCB was mounted. Maybe I'll do vertically mounted SMA ports that pass through holes in the top of the enclosure?

I would really like to get the enclosure design right, normally that is just an afterthought for me I have to just hack it together at the end

Also LaserSteve, that limiter, what power level would you want it to limit to for your SA (spectrum analyzer?).

-Hunter
 

[longh]

I kind of like how these people do their enclosures: https://twinind.com/index.php/products/rfmicrowave/
You do have to solder the rf connector pins to the PCB after the pcb is mounted, but maybe that is ok?

Oh, I also like this one: https://www.gquipment.com/enclosures/53-rf-enclosure-mini-aluminium-extended-fx.html
Definitely overkill for 500MHz, but it looks like they don't even solder in the SMA connectors. From what I can tell they just make contact with pads on the PCB. 

-Hunter

[Terry Bites]

A great idea.
This is an example of a hybrid. Hybrids allow duplex operation over simplex chanels.
The send and retun losses on the same line differ. AKA directional coupling.
Telephone handsets use this principle to stop you shouting in your own ear.
Old school.
https://en.wikipedia.org/wiki/Hybrid_coil