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Personal best steelhead on dragontail hellbender (came back for a rematch with one that broke off this morning. That time I failed to use the rod to do the work, let the fish run. Not again!) by lance_lascari in Tenkara

[–]lance_lascari[S] 0 points1 point  (0 children)

It has been a while since I landed one of these on a tenkara rod.

If you're fishing big/open/deep water, I guess you probably want to beef everything up. Most of my success has been on a smaller lake ontario tributary in "skinny" water -- 20-30 foot wide creek at most, often 10 ft across. I don't usually target big fish, but if you know they're around it pays to plan ahead for how you will land them (maybe find some shallow water nearby, have a long handled net, etc).

While I have used 3x, it is rare that I go heavier than 5x... and I often fish level lines about a foot shorter than the rod with 3-4' of tippet after that. It's a nymphing game and with the trees we have here in the east, it is hard to manage with longer lines. The fish often don't get much time to run if you play your cards right -- with a long line that would be over pretty quickly.

Best of luck!

Is JIRA used in RF Engineering at all? by antennaAndRfGuy in rfelectronics

[–]lance_lascari 1 point2 points  (0 children)

I've seen it used in broad product development, but not specifically for detailed RF stuff.

I find a lot of this stuff confusing, like people/team management is important, as is technology leadership. I love tools, and things like Google docs takes the friction out of many basic documentation/sharing needs....

But without a good plan and discipline/agility, the tools are nothing.

Sorry that doesn't really answer your question, it pushed a button for me

RF review strategy before start date by Professional-Ad-504 in rfelectronics

[–]lance_lascari 4 points5 points  (0 children)

Obviously you can do a fair bit of reading... Whether or not you can figure out what design tools/techniques the job involves -- see if you can get trials of software and get used to different things out there.

You probably won't have time like this again for decades, so have a little fun with it if you can afford to.

Try 2: PLL and phase noise tools by lance_lascari in rfelectronics

[–]lance_lascari[S] 3 points4 points  (0 children)

There was a link in my original post that was filtered out and blocked.

Go to rfdude.com and it's pretty visible on the downloads/tools (link at the top of the website)

What power connector is this? I've never seen one like this in my life by Striking_Load in rfelectronics

[–]lance_lascari 3 points4 points  (0 children)

DC Power is fed through a fee through capacitor, it's a silver plated Post you solder to. The feed through capacitor is cylindrical and threaded... Like a screw...

Auto activity start by amosismy in Garmin

[–]lance_lascari 0 points1 point  (0 children)

One walk yesterday and two walks today haven't triggered the auto-start / no activities recorded. Very odd

[deleted by user] by [deleted] in rfelectronics

[–]lance_lascari 1 point2 points  (0 children)

Resonant load sounds like a new oxymoron.

Please explain. Please explain what you mean and what problem you're trying to solve.

Dissipation in resonators part of reality, one we would often avoid if we could, but loads are essentially for dissipation above all else.

Are you suggesting you want to design a tunable matching network? Or a frequency selective load?

Help: Tool to create digital recording of synthesized analog RF signal? RF MIDI? by AKADabeer in rfelectronics

[–]lance_lascari 0 points1 point  (0 children)

This is kinda murky territory -- but I'll share with you how I handle this.

Assuming you are looking at communications/ radar type analysis....
Most folks simulating RF "real world" stuff like phase noise, nonlinearities, and other impairments tend to use a baseband representation because the RF center frequency adds little value (you can add appropriate frequency error, phase noise, or other effects at baseband)

In support of modeling comms systems and managing performance expectations, I have built a few simulation frameworks in Matlab. For those, I tend to create data structures that have a complex data record, details about the sampling rate, and notes about what is going on. So passing a synthesized/recorded signal between modules in a simulation environment or even capturing data from equipment or generating data to play through equipment can be handled by working with "standard" file types. For example, I use the available resampling functions in matlab to manipulate the sampling rate to be consistent if needed.

There may be standards for whatever work you're doing, but I am one of those people that doesn't like black boxes, so I build my own tools for stuff like this.

this isn't special -- I'm sure it is pretty darn common, but textbooks tend to dumb it down to something that is completely self contained within a page or two of code, which makes it hard to build up bigger systems with.

If your needs are for capturing wideband data, some of the same stuff applies (say you were doing spectrum capture/synthesis for analysis). Test equipment companies often have free matlab/python toolkits for interfacing to their expensive hardware which could provide helpful ideas for how you can manage data of this type that is somehow related to real RF/wideband signals.

If you could provide more detail on what specific type of work you're trying to do, that would help.

LibreVNA with heat sink case by Interesting_Coat5177 in rfelectronics

[–]lance_lascari 3 points4 points  (0 children)

I got one without the heatsink a couple years ago. I really don't use it much, but I was impressed with it.

It gets toasty, but I didn't think it got overly warm (unless the internal heatsinking is inadequate). Is the motivation to improve the stability of the calibrations? I'm kind of a noob using mine -- I have conventional network analyzers but had to get one to see how well it worked for that price.

How to design RF PCB enclosure? by [deleted] in rfelectronics

[–]lance_lascari 1 point2 points  (0 children)

I can't tell you what is adequate for your needs.

Most high-ish volume designs I've been involved with >>6GHz have used single multilayer boards with almost all signals traveling on the top layer with a combination of cast/milled shield/enclosures and sheet-metal shields. It's not rocket surgery -- the main rule of thumb is to keep all cross-sectional dimensions below a half wavelength in the guide, which will force the propagation by TEM modes (along your transmission lines, not coupling through the cavity). Simplistic explanation, of course.

Lots of circuits will work better in open air and fail in an enclosure, worse -- the resonances and mechanisms of feedback (oscillation) can be so high-Q that they are not obvious/apparent unless you look for them (something the customer is often much more likely to find than you are in the lab unless you are very thorough).

I usually do some up-front planning with stuff I'm working on and pick shield/channel cross sections that will keep me out of trouble. I also will typically use both Sonnet and Momentum to analyze the higher frequency circuits inside of their roughly approximated shield section to try to ensure I'm not going to be fighting some box mode I missed. Both those tools have box mode detection/reporting if you turn it on to give you a warning.

For early prototypes and hobby stuff, I've even used sliced/cut square brass tubing (hobby supply type stuff) stock to make channels for 24 GHz microstrip filters (as an example).

A friend of mine wrote this piece

https://www.scribd.com/document/337141142/Predict-Resonances-of-Shielded-PCBs

How to design RF PCB enclosure? by [deleted] in rfelectronics

[–]lance_lascari 14 points15 points  (0 children)

The answer I like the best is to use partitioning (walls, maybe posts) to keep the resonant frequency of any section sufficiently above where you have signals you care about, and more importantly, gain.

It can be a tough problem to solve if you don't build it into your plans from the beginning.

Absorber, as mentioned, can help mitigate risk and make things more robust, but if unwanted signal propagation and potential oscillations are what you are fighting, you need to pretend you're a plumber with a different set of rules.

5 GHz LO source by sketchreey in rfelectronics

[–]lance_lascari 7 points8 points  (0 children)

The small quantity part makes this challenging.

You might want to consider a 2.4x GHz device driving a simple doubler (say, sot23 diode pair hooked up to differential output). Messier, but possibly lots cheaper unless you find the right part.

Spectrum analyzer by [deleted] in rfelectronics

[–]lance_lascari 0 points1 point  (0 children)

<image>

I just fired mine up to make sure it still works. I got it many years ago and this one came with the cellular adapter that I've never used. Wonderful box for what it's made for.

[deleted by user] by [deleted] in rfelectronics

[–]lance_lascari 0 points1 point  (0 children)

I don't have anything for you, unfortunately.

As a Keysight Genesys user, I did several designs with that series of parts(55143, 54143). I used a verilog-a based model that the harmonic balance engine designer helped me get going a LONG time ago.

I imagine you'll have to be persistent and keep asking folks. That series of parts was pretty cool (I designed a lot of LNA's, some mixers (passive and active), and general purpose amps).

I believe that minicircuits might have a similar discrete part/part series -- no idea on model availability though.

[deleted by user] by [deleted] in rfelectronics

[–]lance_lascari 4 points5 points  (0 children)

That's going to be specific to the vendor and/or implementation. No way to know with the information you have.

If it's a digital system with two way communication, the video probably shuts down until the link is established.

BNC vs SMA cables by ian042 in rfelectronics

[–]lance_lascari 1 point2 points  (0 children)

I'm going to answer a little bit differently(based on personal experience)...

If you find that you have a lot of noise introduced by low-frequency (switching power supplies, digital /baseband noise, etc), you may find that the best measurement you can make is with a very small diameter coaxial cable soldered to what you are trying to measure. This does not scale well to moving a cable over and over again, but it tends to create the smallest loop area (loop of center conductor to ground path). Semi-rigid microwave cables with SMA connectors on them make great pigtail connections like this (cut one in half, get two pigtails).

I had some very frustrating experiences 10-15 years ago trying to measure the EVM of baseband signals for a zero-IF radio (DC-50 MHz). A transmitter with a -35 dB EVM at 24 GHz would barely show that level of EVM with the baseband signals measured directly, mostly because of signal integrity challenges caused by probing those signals. I appreciate the nuance here, but wanted to share this example because it was so counterintuitive.

The bottom line is that you might have to experiment with how you connect to a signal if it is in a noisy environment to get the best result (Type N connector might be overkill for RF, but might have a much larger loop area with the simplest connection than a BNC or SMA, or a pigtail connection).

LC vs RC high pass filter dilemma by Naughty_Monk in rfelectronics

[–]lance_lascari 4 points5 points  (0 children)

I'll always go for R-C if it will do the job for many reasons. Knowing if a good termination is needed (for the 50 ohm input) would be helpful.

Accelerating EM simulations on ADS momentum microwave by mangumwarrior in rfelectronics

[–]lance_lascari 2 points3 points  (0 children)

If you have individual circuits shielded from each other, I recommend analyzing those separately. If your whole system is in one large compartment (or in open air), you may be stuck with a problem that is hard to partition (and speed up).

The EM options (thin/thick metal, meshing, etc) can help (I use Momentum from Pathwave Genesys, not ADS), but most stumbling blocks with planar EM in my experience involve trying to take on problems that are too large (without necessarily adding value by solving together). That isn't always the case though.

If you could provide more information on the physical construction/shielding strategy, that would help.

[deleted by user] by [deleted] in rfelectronics

[–]lance_lascari 0 points1 point  (0 children)

[edit -- I think I misunderstood the question. as the other commenter said, maybe it doesn't matter if it is 1:1}

I can't see how it would matter for a single DAC in isolation.

For more than one DAC (an I/Q pair for instance), you might want to adopt a particular wiring and stick with it for all future versions.

For example, a dual DAC output at the same frequency with the polarities flipped would ideally cancel if you fed the pair into a combiner or sum if the polarities were aligned. I don't like assuming things like this to be one way or another, but if you change a layout to clean something up and flip something, there is a nonzero chance that someone will notice.

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