#1459

Episode 1459
comes with coax 'attached'
Be a Patron: / imsaiguy

[@ivolol]

Me thinks IMSAI Guy should invest the help of PCBWay or JLCPCB to put all these ebay and chinese yagi makers to shame, and make a proper functioning 2.4ghz yagi for fun. Or at least show them a proper design to copy from 🤣

[@andrsam3682]

Very active flux (with acids) can really damage the board. Some fluxes are conductive (bad ones), so they must be cleaned.

[@K1ZEK]

You have a way with words, and know how to stir the pot. Your videos like this one keeps me on my toes. 😅 Lots of fun watching your videos. You make my "little gray cells wake up " 😂 . 73 Leo. K

[@jms019]

Definitely ask for your money back to punish bad clone sellers. People without your knowledge will have made things using this that don’t work as a result.

[@herbertsusmann986]

I have seen cases where flux causes leakage between traces. Circuit was high impedance like 1 meg ohm or so. Flux absorbs water over time and becomes slightly conductive. When I cleaned the boards problems went away

[@Dreamlgider]

I knew exactly what you did with that Thumb of yours instantly, even before you flipped the board 🤣🤣 Keep them coming. 73

[@IMSAIGuy]

you've been watching too much card magic

[@catalino8010]

it got me but when he took it out and saw the connection, i laughed

[@johnwest7993]

You definitely know what you're doing, and even if I didn't already know you're good, what looks like a Metcal and a Panavise would be a pretty good hint. But even some guy in his garage would figure this one out. I did a repair and calibration on a board made in-house at NIST. After returning it to NIST I got a call from them. They wanted to know what in the world I did that dropped the board's noise floor 10 dB. I told them I'd cleaned the flux off the bottom of the board. Scientists, sigh. The relationship between element lengths and widths, and distances between traces is set for the desired impedance matching, forward gain, and bandwidth, as you instinctively know. This layout is suspicious because all of the directors are the same length and spacing, a very simplistic Yagi-Uda design topology from before the time when everyone had a PC and a copy of one flavor or another of NEC, meaning it was just slapped together by someone not using NEC to 'look like' it was 'designed' when in fact, they just looked at an image of a board design and roughly copied it in a graphics program and said, "Good enough." I'm surprised the 'correct' configuration is as close as it is. But if it were me, I'd use a PCB Yagi-Uda design program, select FR-4 for a common dielectric material, (unless I wanted to get fancy, improve efficiency, and spend some one else's money on a Rogers material suitable for the frequency,) and whip up my own. I think "Some guy in his garage," could do a Hell of a lot better than what you have there.

[@vincei4252]

I'm 2 minutes in an I'm really hoping that the genius that "designed" this didn't tie the center conductor to the braid via those vias which I'm guessing are plated thru. [edit] My word, what they did was way worse than I imagined. RF Enthusiast indeed.

[@willthecat3861]

These pcb yagi antennas are still available on Ali... all over the place.

[@0MikeG]

Thanks! Will sleep better and worry less about flux...😀 Were I live now, normal consumers can't buy leaded solder. So I pick up a 454g spool of 63/37 when travelling... I have some NC (no clean) but more rolls of RA...

[@jeonghutamilim2259]

Manufacturers / designers rarely have any idea what they are doing. They get something to work, get minimum required certifications and sell it like it was best invention since penicillin.

[@ThinklikeTesla]

Got some conductive copper tape? You could lengthen those directors.. And the reflector might need to be shortened. Sounds like a fun experiment!

[@IMSAIGuy]

part 2

[@jspencerg]

I'm thinking the same thing. Easy to make.

[@wjhann4836]

Well in the late 70th I was in the air force repairing measurement equipment. I sometimes got instruments back 1/2 year later - inaccurate. Then I washed the PCB in Alcohol (ultrasonic bath) and the results got better. Later I can't tell you because every repaired PCB got washed.

[@TheElectronicDilettante]

Calibration(?): When a calibration is done for a given frequency range and saved in memory , isn’t the purpose of the saved calibration to avoid having to do a physical cal every time you perform a measurement? Thanks again!

[@TheElectronicDilettante]

I’d never presume to question your knowledge or experience regarding any of the topics you’ve covered. Just out of curiosity, did you hook it up to the VNA before your fix? I only ask because I just watched your video on micro strip/ patch antennas and a video on micro strip circuits in microwave RG amplifiers . I noticed a lot of them seem capacitivly coupled and not mechanically attached to anything else. That being said, I also saw the video on your tear down of an HP switch/relay control unit. The PCB of the front display panel had a bunch of trick looking gold plated traces. Since you were scraping the unit, using predetermined measurements, could that PCB be cutdown to render a PCB antenna or pieced together to make something similar?? As always, thanks for the videos. If you’re trying to think of content for your next video, and since you seem to have the ability to do some machining, would be so kind as to revisit resonant cavities and their application to RF design. Thanks again!!

[@rickwise9910]

I've never had a problem caused by flux. In the Army, QA would ding you for leaving flux. Their justification was that it could hide a problem in the joint.

[@bobkozlarekwa2sqq59]

I agree with your diagnosis. Why not try and design your own? Aside from resonance, is it directional?

[@tvelektron]

I am more or less sure to see the own design very soon 😇

[@wiwingmargahayu6831]

happy ramadhan fasting

[@WolfmanDude]

That is hilarious! As an idea for a future video maybe check out those "wideband power amplifier" modules from china. In my experience they actually "work", but the output transistor is so overbiased that they blow up after a minute (literally!). I had 2 different variants with the same problem. I dont think the factory even knows what they are producing or how to test them.

[@IMSAIGuy]

I've done several videos on chinese amps. I even rebuilt one with a better part.

[@WolfmanDude]

@@IMSAIGuy Ah ok cool, will check that out later! Sorry, I am kinda new to your youtube channel

[@haraldlonn898]

Not the last time we get stuff from east land and it is wrong built. It is just that you get what you pay and made in own country is often worth the money.

[@rayoflight62]

Few years ago I bought a drill bits set at a car boot sale. I paid five UK pounds for ten drill bits, from 1 mm to 10 mm Φ. I realised I had been scammed at the moment the drill begun to spin, as the bits were made of that infamous zinc alloy...

[@cesarguevara5144]

quick question the ground of the antenna the wrapping if you will, shouldn't it be connected to the other side of the dipole? also shouldn't the reflector be a inactive element?

[@tze-ven]

I know this may sound insane, but have you hooked it up to the VNA in its original form. It might hit the sweet spot of 2.4GHz. 😜

[@ghlscitel6714]

hilarious!

[@Chris_Grossman]

I would have fluxed the braid before soldering.

[@willthecat3861]

Texas Instruments... some decade(s) ago... published the complete design, and test results, of a 2.4 GHz, 4 element pcb yagi. It's all over the Net... and has been prodigiously... even copiously... stolen.

[@nooneyouknow9399]

Spotted the error in the first second. Flux? Heck, why do soldering right eh?

[@StuartM0TTQAmateurRadio]

Agree with all your comments on the dimensions and spacing of the elements. Looked completely wrong!

[@galileo_rs]

If the dielectric on that cable wasn't teflon there would be no way to create the semi rigid shield. Looks like RG402 to me.

[@kreynolds1123]

It might be the dielectric properties of the boad might change its resonate performance. Also, It may help our comments on the design if you include dimensions in the description, or a link to a page with a diagram and dimensions.

[@IMSAIGuy]

this may be of interest: kzbin.info/www/bejne/nYralquanNuImKcsi=KsjWtWys7FAmrtqd kzbin.info/www/bejne/sIfOm5iLnLGJotksi=XtdqB5qD-RG7TWPv kzbin.info/www/bejne/fIOyhKOrnNmAbqMsi=COxDXVdoWWljLjRe

[@leetucker9938]

new to the channel . i like it

[@rgigliotti7576]

You MIGHT TRY DRIILLING a hole either side if thr braid off the coax and solder wires through the 2 boards to see if you can get a better gnd to see if it makes any difference ???

[@vincei4252]

it's a 2.45Ghz antenna with a bonus dip at higher frequencies 😇 Is it possible that the original Antenna design was on Rogers material and the genius that built this thing just slapped the design on FR4 ?

[@johnwest7993]

I think a design on Rogers wouldn't have had all the director elements the same length and spacing. That's a simplistic 'pre-NEC' and home PC Yagi-Yuda design from back when it was all cut and try designs.

[@Ziraya0]

Would it do anything to solder some material on top of the board to extend the elements to their proper length, as a demonstration?

[@IMSAIGuy]

part 2

[@kurt9232]

Now they should know how to build it. : )

[@mnoxman]

10 Minuets of QED on why you have "trust issues" about (Chinese) electronics.

[@BobHolowenko]

"Custer Flux" ROFL 😂

[@W4TRI]

Reflector and ground side of dipole connected? Does not look right either?

[@yveslesage8525]

I agree..it looks weird and wrong. If the antenna is to be used vertically , the coax shield connected to the side of the dipole facing the ground would be OK but if used horizontally, a small, easily homemade balun would be better to balance the asymetrical coax.

[@khimbittle7705]

Since u have a pcb supplier might be fun to layout one of your own dimensions and test.

[@Randrew]

I would (and have) just experiment with copper tape on a blank (no copper) FR4 board before committing to even a cheap-from-China custom board run. That is, I have experimented that way, but never committed. I used copper craft tape meant for (I think) stained glass work.

[@khimbittle7705]

@Randrew that's a good idea, when I get some spare time will try similar and then test with the vna thx

[@Patrick-rj8gh]

I remember my old physics teacher saying something about 4nec2 software being used to design antennas. Does anyone use that? Is it useful for optimising this antenna?

[@IMSAIGuy]

kzbin.info/www/bejne/i17GdJd9mctprKs

[@4ib03_ryanramadhan8]

can anyone helping me design how to make yagi antenna on PCB pleasee 😭 i rlly need the teory about all of this

[@uni-byte]

I imagine if Bill Hewlett or Charlie Litton were still alive and had YT channels there would be a litany of Dunning-Kruger subjects posting that they don't know what they're talking about. Ahh, the internet..

[@RoyArmy-WREW918]

Still waiting for your PCB Yagi design ... 😆

[@Dennis-uc2gm]

I've always been the kind of person that questioned everything. Needless to say some of my teacher's didn't like that approach. Even a great design deserves questions of how they got to that particular implementation of the collection of parts that does a certain function. 🙂

[@herbertsusmann986]

Alot of stuff coming out of China these days is cheap copies of good stuff. They will learn over time but right now it is too easy to make money this way. I avoid Chinese products unless I know they are quality. Also I like to support domestic suppliers whenever possible. Very dangerous to become too dependent on a single country for goods.

[@radiok2ua]

I think you were too kind. And I like how you call out the armchair guys who criticize you for "doing it wrong," along with a demo. Nice.

[@bazzaar1869]

Good grief that's junk! I would check the connection of the SMA under that heat shink too after seeing the epic fail of a connection to the PCB/antenna! There is a solution of Yagi design that has all the directors the same length and spacing, but its far from optimal so not used. Also, mounting holes at the ends of the "reflector" ?? If you did mount it to something with them what's that going to do to the performance? Those ends are voltage nodes, they need to be in free space I'm with you on the flux topic, some people seem to learn that there IS corrosive flux and so ALL flux must be corrosive! Plumbers flux and Aluminium flux are the only ones I worry about.

[@arturjski5661]

You haven't measured whether there's continuity between coax shield and sma connector. Because, you know, Chinese assembly quality 😀

[@jspencerg]

How to model Yagi design? Otherwise, it's hand waving or trial and error.

[@IMSAIGuy]

cad programs: kzbin.info/www/bejne/i17GdJd9mctprKs

[@jspencerg]

​​@@IMSAIGuy 1459-1118=341 days/videos ago. What a way to measure time! I forgot that one. Did your converted HP VNA stop working?

[@IMSAIGuy]

@@jspencerg it only goes to 1.3G

[@willthecat3861]

There are .... a lot ... or Yagi-Uda (yagi antenna) calculators online. (You can add directors, the antenna configuration, the gamma match... the whole nine yards... and they will spit out the dimensions of the elements.) If you mean, to model the electromagnetic response... of a particular yagi design... then good luck, and best wishes.

[@IMSAIGuy]

@@willthecat3861 yes there are, I see them asking for the diameter of the wire used, but never the width of a trace, and never FR4 sheet on one side.

[@InflatedDolphin]

My only real question is what is this thing aimed at? It's not really of any use to anything I can think of. Even if it did work as advertised.

[@IMSAIGuy]

wifi

[@InflatedDolphin]

@@IMSAIGuy I know what it is aimed at, but still can't think of a "use case scenario" where it fits. Even 13cm band antenna's are different to this. If your WIFI is so bad you feel this thing would help, I would say your need either a better dongle or better router. I haven't seen a mobile phone or laptop with an SMA connector fitted as a connection standard. Yet.

[@IMSAIGuy]

@@InflatedDolphin usb dongles for wifi with SMA are very common

[@InflatedDolphin]

@@IMSAIGuy I am aware of this, I own 6 of them.....my point was there is NO LAPTOP or PC video card I have seen that comes with SMA by default. I did actually say this in my comment above, however I think you missed it. I merely commented that I can see no benefit this contraption would provide. As I said, if your WIFI connection is so bad you need an external antenna for a dongle, there are far better options than this. I assume this may become relevant in an apartment building or campus dorm where there may not be a router nearby to utilize, but for an average user the router coverage should be ample for MOST cases. I can still see and connect to my WIFI from 7 houses down my street, It might only get a 54mb connection instead of the 300mb I get when in my house, but I still wouldn't need something like this. It seems things like this a designed solely to relieve unknowing people of their money....for no real world advantage. But, if this is how people wish to go, then it's their own free choice I guess.

[@zerobow9413]

Junk !, I just bought five large log periodic PCB antennas only one of them actually works ! The Real RFspace one was a fail as well, funny enough the Deepace 850Mhz-6Ghz was ok

[@fredflickinger643]

Better to build your own vice ordering a substandard unit and wasting a whole lot of resources!

[@alanvandusen76]

I take it the Monday morning quarterbacks got you down? Don’t let the haters hate 😀

[@IMSAIGuy]

Thanks

[@mr1enrollment]

I hate flux for no good reason,... but better than being in a cult.

[@joeteejoetee]

ROTFLMAO !

[@HA7DN]

But the designer clearly knows better, you haven't tested the original before you ruined it via your soldering! /s

[@ronostrenski8359]

Agreed, piece of crap. It wouldn’t be hard to design a much better one and post the design. See how long it takes for them to clone your new one. Regards from VK4JBY. 👍