Experimenting with waveguides using the LiteVNA

[joeqsmith]

I got a wave guide tuner to try to see what will happen to VSWR with it. should have the setup in like 1.5 months 

i got alot of captains, pilots and drivers im depending on for this setup

In route then along with other goodies?   

I have a few slotted line stub tuners that came with that box of junk.   One of the experiments they had the students perform was to measure the VSWR and tune it with an open end.    Showing my results, yellow is open ended transition, red with the tuner attached and trimmed.   So we can certainly reduce the VSWR.    You may remember that very first section of home made WG and my pork and bean cans had stubs on them.   You could drill a few holes and add a few set screws.   Then you don't have to wait. 

[joeqsmith]

Here is one of the workbooks I had found on-line.     

https://tecnoedu.com/Download/56-200.pdf

[coppercone2]

Yeah, but I also am debating if I should get some flex wave guide. I feel like the circuit is going to be hard to put together without any flexible things. Not sure what I want to make, I see there is a few different Ku band things like the x band spectrometer thing that guy was building here, maybe, but in general, it seems that I would need some spare wave guide tube and flanges to braze on to make a custom circuit that connects to the VNA with all wave guide. I wonder if anyone even does that

Do you know the difference between E&H Tuners and the sliding tuners ? Hard to find info on them. Is it a choice based on power level? I think it would be nice to use as many wave guide parts as possible, its interesting to me, there is always some cost saving substitution involved normally

I can try that experiment if I get a few more things. Debating between some options and styles for some of the parts.

[coppercone2]

you need quite a bit more hardware for that PDF then what I have. But I think if I get some of the basics then its a good way to make a setup like that and experiment with self manufactured parts.

And of course I need to build a case because this is going to get out of hand

[coppercone2]

btw for wave guides, I wonder how 3d printed wave guide filters would look like. The Iris type filter looks very printable, just glue a lid on top with conductive epoxy after printing. or the dip coat. Being able to crank those suckers out might justify buying a gallon of silver paint. I think maybe like you can take a 1mL sample of the paint can too, to weigh it, if you plan on keeping it for a long time, so you can add the correct amount of lost solvent to maintain the mix.

I think x or even Ku band might work, clearly, based on how I see the horn functioning on the VNA.

I gotta say I feel a bit.. redundant printing just wave guide conductor sections, the horn is marginally interesting but its still quite simple, but making arbitrary filters in a few hours is damn interesting.

I am just saying it does not feel very special. But band pass filters seems next level.... that seems like a capability not being a cheap skate, and its really new grounds, not reinventing a 'wire'.... their highly non standard parts, not common elements.

https://www.sciencedirect.com/science/article/abs/pii/S1350449513001667



I feel like the doc lol, its not quite uranium but its the first time in my life I felt like I could really use a big quantity of a precious resource to do something scientific.......

[joeqsmith]

The SignalPath video where I showed his attempt of a 3D printed horn, he also shows a 3D printed filter.   I've seen other articles where people have 3D printed them with decent results.  For example: 

https://www.egr.msu.edu/eceshop/testingfacility/connex/papers/3DPrintedMetalizedPlasticWaveguidesforMicrowaveComponents-1.pdf

[joeqsmith]

Do you know the difference between E&H Tuners and the sliding tuners ? Hard to find info on them. Is it a choice based on power level?

See attached.  Full catalog may be found here:
http://hparchive.com/Catalogs/HP-Catalog-1960.pdf

I've not yet had a need for flexible line.   I would like to replace the amplifier, cheap adapters, coupler and filter on my frequency converter.   

[coppercone2]

I got my tuners, wow, I am glad that objects in the ebay pictures are smaller then they appear.... (got the 870A)


Looks like the right choice, its a power level thing mostly. I won't be doing that kind of research.

[coppercone2]

I wonder what kind of stuff connected to wave guide has such attorcious VSWR (20) that needs to be corrected. Very specific radiation pattern and polarity stuff?

[joeqsmith]

Maybe attach a shorting plate and then try to correct it. 

[coppercone2]

I think it must be something for apatures maybe for small samples that need testing at a specific wave length or something?

Like you would think that if the VSWR is greater then single digits it would for sure require a redesign. I see the old VHF bridge from HP went to 2000 ohms for <1GHz. Information on such reflective objects being used practically is low I think

and this previously resulted in people discussing chokes, so I guess it might some how be useful for that. Something with isolation etc

you kind of covered it here, with ohms instead of VSWR
https://www.eevblog.com/forum/rf-microwave/high-resistances-at-rf/



But the question in my mind is still: is there some kind of absurd antenna that has extremely bad VSWR but does something otherwise unique. Say extremely narrow beam width or something. That kind of makes me think of those quantum antenna / emitters. Alternatively maybe a kind of like a laser line scanner type deal, but for microwaves. Like horn antenna vs squegee. borg scanner beam 

[joeqsmith]

Antenna wise, I can't think of anything.  If it's that far out of wack, I doubt it will radiate.  Why add a tuner when you could fix the problem? 

I've ran many experiments that had I measured VSWR, it would be well over 20 but I can't think of a case where I wanted to compensate for it. 
I was playing with that hybrid T and could see if you were attempting to use it to measure something unknown, you could use the tuner to balance the bridge and then use it's micrometer as a readout. 

[coppercone2]

oh boy I took the tuner apart to grease it and it does not have alignment stops. Centering the pin is gonna be a pITA

I thought there is no way there would not be a guide pin or something to setup the rails. But the rails turned out to be glued plastic and there is no guide pins or shoulder stops or whatever.


Probobly need to play with gauge blocks or something to parallel them and fix the thing in the middle


I guess it does not need to be precise but I seriously imagined some much much much more advnaced mechanical hardware to do this! its like cheap! mine would be like a grinding machine x y table!


dare I say : proxxon quality 


tldr : its made with wind shield wipers that need to align a precise mechanism! stomach ache!@

For some reason this wave guide stuff reminds me of startrek deep space nine, the episode where star fleet decided to loot the abandoned station to replace wave guide or whatever the hell is in those conduit runs. Wish I could find a old HP ware house of these 'guide rails' (maybe you can use mazda wind shield wiper blades or something). One of them is missing some chunks of rubber-plastic or whatever. Quite ratty. Thought it was cardasian but its fernegi

[coppercone2]

do you know how the depth stop on a SWR meter tuner should be set? One of them actually has the micrometer digging a groove into the wave guide, I guess you put a shim?

*getting delirious from trying to align this thing

[coppercone2]

never mind, its just a grime mark, the micrometer was properly set, but enough crud accumulated on the wave guide to make it look like it got scratched. phew

[coppercone2]

as usual, after working all day eager to get the job done trusting the seller it turns out their X band and they don't fit the fucking antenna ! I have been working on that shit for like 2 weeks and I still can't tell the difference

into the rabbit hole i go

I say there is about a 30% probability of receiving the correct size wave guide part through resale.

The solution is to get both bands. I am sure I will end up in either the THz region or receive a pallet of WR2300 eventually............................................................... its just square right, you just need it to prop up a shelf. total fucking worm hole, you don't know what dimension you will pop out in.

[joeqsmith]

as usual, after working all day eager to get the job done trusting the seller it turns out their X band and they don't fit the fucking antenna !
...

I thought all the old HP waveguides were prepended with the band.  So X870A is for the X band, using WR90.  Normally if the part is no longer marked, I will just ask the person to measure it.  I have had to do that with some of the salvage yards.   

You could make adapters to go from what ever band you are working with to the X and back.  Then use the tuner to correct for all the errors you added.   

[joeqsmith]

I should have wrote, read that manual I linked as the letter designation was not standard at that time. 

https://www.microwaves101.com/encyclopedias/frequency-letter-bands

[joeqsmith]

Photos were taken from my 1950s MIT RADAR book. 

[coppercone2]

Oh no the picture was diff then what arrived and it arrived in diff quantity . Mad fail . But at least I did not get tucker Carlson coffee mugs or something

[joeqsmith]

There are a few P870A as well as the P880A there.   All fairly inexpensive.   

If you ordered 1 and received 10, I wouldn't bitch too much even if they were the wrong ones.  Resell for a profit and buy the right ones.   

https://www.ebay.com/itm/310953362258?epid=1918800173&hash=item486643c352:g:B3oAAMXQ2UVQ5dvq&amdata=enc%3AAQAIAAAAwGJbZk1BI3Dl6MFo7%2B0VB8WjwzEk2iNbYRieNQ9yjQoz%2FtTEh3ebEN8b%2FVFOW6gBLuuD8rfoZjqxmSKJYgA3SvR7IazzBKH1wKmt9PK9FxspGo82cUd5tAAMut8tJWUNhnFRg5FJF5IVhTRmM%2BdZCuCIGOcxR9cKxRAK5XVdip%2BwymtFRhpDYnuKrmRyZ1fs5F7DH%2BoGot0T7lNGBIRVHlOknJUztYpndKJXwqLztqGQDcxcUlanh9Vu4jO3o%2BA0gQ%3D%3D%7Ctkp%3ABk9SR7Tbwv38YQ

https://www.ebay.com/itm/223942490007?_trkparms=amclksrc%3DITM%26aid%3D1110006%26algo%3DHOMESPLICE.SIM%26ao%3D1%26asc%3D20201210111314%26meid%3Df49cf473079c47f6a528705deedb3386%26pid%3D101195%26rk%3D4%26rkt%3D12%26sd%3D310953362258%26itm%3D223942490007%26pmt%3D1%26noa%3D0%26pg%3D2047675%26algv%3DSimplAMLv11WebTrimmedV3MskuWithLambda85KnnRecallV1V4V6ItemNrtInQueryAndCassiniVisualRankerAndBertRecall%26brand%3DHP&_trksid=p2047675.c101195.m1851&amdata=cksum%3A223942490007f49cf473079c47f6a528705deedb3386%7Cenc%3AAQAIAAABUA2rugFlOq3qu1cLac%252F%252Fk6Vp0Oa0HaJIqoXKeIiOR%252BTUgsSvHaeyPxKYu6UqHqq7GaGyKVqHQnjeiiXcQpMGw2t3aB%252BssGfjtIWOBj8wExc7oYYP7xGMyQCrHDyDaSaWjB1CueI3A94n0yxXX5dx5gAAXolEeNO8u8k6D92DWA4yCIJxgBKBicSQlyh7C5d2KjB%252FeXfcretsgT8RvDI%252BujKBKhSsmiRMLh3piQ8nDAtf%252BsYCcCXEZQsU4konEYAyoS533y8TH71w262HFz%252BLZATtnSVOyFEHVql9Jfw4UyDn%252FKkPRXS%252BhkjlkbgPQQXkH81DAwODDtXK8nN3w9pIydpkH5ha%252Bj3fDvLtvNtBr4G1DeIwiiYf4VRtZKRnSPoZxXZCEZtA297Xn%252Be9APZGc0y%252B3HWAkGncxNGTqCSwPbJyoyeb9o2ny0PuK5yAUJ1tLw%253D%253D%7Campid%3APL_CLK%7Cclp%3A2047675&epid=14039252709

[coppercone2]

Lol yeah, I wanna get into this band also I guess, just you gotta be in it long haul, no quick anything when it operates like this.

What I want to do is develop a bio implant that makes a caliper or ruler shoot out from your knuckles like wolverine

Maybe I will attach a caliper with a magnet on it to the refrigerator or something, or even a ruler. Maybe a ruler tatoo

[joeqsmith]

I replaced the 8GHz amplifier and the adapters.  There's a slight improvement in performance.  Still using that coupler way outside it's spec'ed range.

[coppercone2]

What do you think is the integrity for those wave guide loads?

I assume its like a big carbon composition resistor? I have SERIOUS doubts about old ones being 'good' if its carbon comp based.

Are calibration wave guide loads... carbon composition?! I am allergic to purchasing carbon composition unless I can replace it with something. I usually put metal oxide in everything I have the time for.

[joeqsmith]

They are mechanical so unless they were mishandled or left outside, I would expect them to be fine.   In my case, I used matched load to measure the mismatched load and it seems fine. 
Considering these parts most likely were from the 60's, they have held up well and are good enough for my home experiments. 

Of course, you could purchase new standards.