That audio choke flange is fascinating

I just found your channel after seeing your video on FPGA based CPUs. I am impressed at your skills that really span a range of topics. I look forward to future videos, thanks!

@joesmith-je3tq

Жыл бұрын

That large FPGA board uses a 100MHz clock and was the fastest wire wrapped project I ever constructed. I read a book 20 some years ago who's author's worked at Intel. They discuss modern digital designers and the need for them to understand basic RF. They consider the VNA as one of the basic tools. Consider where we are today with high speed digital.

wow, this series about waveguides is getting more interesting l hope that the fourth part arrives

That was fun and educational, Joe. Thanks!

I want a part four, great video.

Heres a request. It would be interesting if you did a video on how to work with the rigid coax cables that were part of your mixer test board you used in your last videos. What do you look for in purchasing them, how do you safely bend and connect ends onto them to minimize leakage and distortion, and perhaps even basic rules to follow while handling them. Comparing their superiority in S-parameter characteristics against standard non-rigid RF coax might also be a cool thought to consider? I havent seen many people work with the rigid coax at multi-GHz frequencies and thought you might do a thorough job discussing it, as you have done with your other excellent videos. You could make good use of your VNA software to run evaluation tests. It's just a thought... thanks.

thank you

I'm wondering if copper or alu tape could be use to cover your plastic horns for a really cheap option

@joesmith-je3tq

Жыл бұрын

As I showed in the Part1&2, foil tape can be used.

Thank you for another excellent video. What is the thickness of the conductive coating vs. the skin depth? I would think that would determine how thick of a coating you need. Do you think the VSWR of the ESD material may be lower because the material absorbs some energy? Is the peak of the response with the materials a property of the material, a resonance set up in the cavity by the mismatch it causes, a combination, or something else?

@joesmith-je3tq

Жыл бұрын

As far as the skin depth, beyond what they have published, I have no idea. I never tried to contact the mfg. I'm guessing you have looked at the datasheet and application guides. They show 2 mil or 51 μm per coat. Their graphs show up to three coats, which is why I continued to go up to double to see the effects. We don't really know how thick it is but it could be measured. They also show an attenuation graph based on two coats. We know the makeup is copper silver something and at 10G would be something around 70 um. Yes, I do believe that both the ESD and conductive plastics act as an absorber. HP and others have published some very good papers on measuring materials using rectangular waveguides. If your Google foo is poor, the following paper should get you started: ntrs.nasa.gov/api/citations/19950023915/downloads/19950023915.pdf

I have a duel-band microwave radar jammer kit from 1980's I've never assembles - maybe I'll put it together and test it with my new VNA.

@joesmith-je3tq

Жыл бұрын

I'm not sure how you would go about doing that but it sounds interesting. Consider posting about it and I will follow along.

Joe, if you have the time and are interested I'd love to hear your explanation of how this filter for Apollo craft works ( kzread.info/dash/bejne/mnZ_qrB6dNe0gNY.html ). Guys who are restoring this old communication equipment are very skillful but even they called this filter rf black magic. The one at 7:32.

Joe at 2 times playback speed, sounds a little like @Ben Eater.

@joesmith-je3tq

Жыл бұрын

Sorry, I have no idea who this is.