What is this?  - Page 1
Forum section: electronics / repair

author: ejd.pol
author_rank: Contributor
timestamp: March 29, 2025, 05:01:15 pm
content: Hello,Recently i came across the following (see pictures below), and I acquired it purely out of curiosity.I have never seen anything even remotely like this.It is all composed of passive components, and the physical structure is delicate and detailed.For example, the two (shielding?) plates that can be seen on some of the "towers" are closer than 0.5 mm.The spiraling windings that can be seen are all different from one another, and are wound unevenly.The best I can make of it, is that it is some kind of antenna system.The black pillars are presumably ferrite rods (two have been broken off, alas).The six towers (each with two ferrite rods) seem to have a very specific geometric configuration,which leads me to suspect that it is some kind of mimo arrangement.So it may be a vintage radar antenna, perhaps?Anyway, I'm curious to hear your opinions and guesses regarding this construction!Please let me know if you'd like to see a zoom-in on some detail, then I will add that in a next post.Kind regards, Evert-Jan [ Attachment Invalid Or Does Not Exist ]

author: ejd.pol
author_rank: Contributor
timestamp: March 29, 2025, 05:23:50 pm
content: Here are the pictures:

author: timeandfrequency
author_rank: Frequent Contributor
timestamp: March 29, 2025, 06:36:54 pm
content: Hello ejd.pol,I've never seen such kind of parts.Could be some kind of RF tunable filters.Seems to be 40' or 50' technology.

author: TimFox
author_rank: Super Contributor
timestamp: March 29, 2025, 07:03:52 pm
content: Maybe helical resonators (q.v.) used as filters?

author: jwet
author_rank: Frequent Contributor
timestamp: March 29, 2025, 07:09:26 pm
content: That is some real exotica. Likely a fancy helical filter- is the grey piece that holds them all a waveguide (are there holes that inject signals into the coil assemblies?My best advice is to post it here in the RF subgroup, there are some old timers that might know it on sight.There is also a great surplus store called "Surplus Sales of Nebraska"- link-https://www.surplussales.com/they've seen it all! I didn't see anything that looked like this in their current stock.Good Luck- post what you learn please.

author: ejd.pol
author_rank: Contributor
timestamp: March 30, 2025, 10:20:13 am
content: Hello, thanks for the responses!I have had a close look at the grey central piece that holds everything, and as far as I can tell, it is not a waveguide.There are no holes to be seen that may be used as entry for a wave, nor are there any holes or other structuresin the circular clamps that hold the ferrite rods. So it just seems to serve a mechanical purpose.One remarkable observation is that there is a soldered connection underneath each (all 12) ferrite rods.On close inspection, some of the solder blobs (not all) seem to have a small piece of thin wire sticking out.It does not give the impression that something was cut off, it looks more like the wire goes into the clamped base,as suggested by some of the solder blobs being entirely smooth balls with no cutting marks or anything of the sort.I'll try to cross-post, but I need to get some support from the admins, as that seems to be "not done".(At least, on a previous occasion, that was the message I got...)Anyways, I'll keep you posted on progress!Evert-Jan

author: jwet
author_rank: Frequent Contributor
timestamp: March 31, 2025, 02:31:29 pm
content: Thanks for the update, more curious than ever.This is why people talk about RF stuff as black magic, this kind of stuff gets really close.

author: ftg
author_rank: Frequent Contributor
timestamp: March 31, 2025, 02:59:01 pm
content: It could be a filter bank from some old equipment.None of them are the same, but there is a clear progression in the inductance.And two resonators next to each other makes me think about a double tuned filter.Do the long ferrite rods have tuning screws accessible from the top, when the coil elements are like shown in parts3.png?In addition to the frontend of a radio, it could be from some signal generator for example.The "5800400-0427.001" sounds like an R&S part number, but ddg finds nothing relevant.

author: coromonadalix
author_rank: Super Contributor
timestamp: March 31, 2025, 05:04:53 pm
content: i would have said filters coils or signal filter for radio ham equipment or else, I/F filter etc ... the long rod seems to be tunable ?? or adjustable ??

author: timeandfrequency
author_rank: Frequent Contributor
timestamp: March 31, 2025, 05:19:14 pm
content: Quote from: coromonadalix on March 31, 2025, 05:04:53 pmThe manufacturing quality and the materials used seem above to what was devised for ham radio communication.This sub-assembly comes rather from a military gear (radar system, radiocommunication set, radiotelescope receiver, spacecraft telemetry, fundamental physics experiment) or from an RF TE.

author: Haenk
author_rank: Super Contributor
timestamp: April 01, 2025, 04:51:25 am
content: Dated 1952, it seems.Stamped SEL, that would be Standard Elektrik Lorenz - they were a major manufacturer of radio equipment at that time.

author: Perrold
author_rank: Contributor
timestamp: April 01, 2025, 06:25:39 am
content: Permeability tuned coils most likely. I'm not familiar with Euro equipment but these were common in older US gear. All the rods clamped in that cast frame is a big giveaway and the tab on the end just screams that it slides in something. For those bored enough, look up pictures of coil racks in some Collins equipment. While mostly used in high end mil gear, permeability tuned coils also found a home in car radios and even some domestic radios. Done properly, this can be a very mechanically robust solution nearly immune to vibration and also the associated microphonics. With fancy windings and linearization cams, the transfer function between mechanical input and resonant frequency can be incredibly linear, on the order of 0.1% or better. The Collins PTO is probably the ultimate manifestation of what can be done with this technology when cost and simplicity take a back seat.

author: ejd.pol
author_rank: Contributor
timestamp: April 01, 2025, 06:31:04 am
content: Quote from: timeandfrequency on March 31, 2025, 05:19:14 pmI would concur with that remark: the quality of the materials and and intricacy of the construction indicate it comes from some professional gear.The amount of precision handwork that went into this would seem to be too much for mass production.As an answer to other questions: I don't think the rods can be tuned somehow. To be more specific: I have not discoveredanythingthat can be adjusted!

author: ejd.pol
author_rank: Contributor
timestamp: April 01, 2025, 06:48:55 am
content: Quote from: Perrold on April 01, 2025, 06:25:39 amMany thanks for these pointers! I just a (very) quick search before heading off into work, and the picture below of an IF transformer comes indeed quite close.And I guess it no coincidence that the advertisement says: military surplus!

author: ejd.pol
author_rank: Contributor
timestamp: April 01, 2025, 05:47:16 pm
content: Quote from: Haenk on April 01, 2025, 04:51:25 amHello Haenk, I followed your indication, and started looking into the Lorenz company.I found some conflicting information, perhaps you can help to clear up the confusion.According to the website of Ralf Klaes (antik-radio.de), the name Standard Elektrik Lorenz was introduced in 1958.(See the attached screenshot.) That would presumably mean that in 1952, SEL did not exist yet?What was it that indicated to you that the array was made in 1952?The number imprinted on the base starts with 58, so perhaps that could indicate the year of manufacture?I also had a good look at the stamping on the ceramic tops of the pillars, and they all seem to consist of two lines,the top line always being "SEL", and the bottom line being "WI" plus a two-digit number (spaced apart from the WI).The numbers are difficult to read, but I think there is an 09, and 11. There are also other numbers, but unreadable, alas.Perhaps WI means something like Week Index (Wochenindex) ?I tried to search for SEL-related images or documents that show a similar array, but I was not able to find anything close.If the equipment was made specifically for the military, then it is no surprise there is little evidence to find.In case you have any more pointers for me, I'd be happy to have a further look.Many thanks, Evert-Jan

author: Haenk
author_rank: Super Contributor
timestamp: April 02, 2025, 05:20:50 am
content: Yes, the date would not be 1952, though it might he possible they used older stocked parts - military devices usually have decades of parts availability. Just a guess.No available pictures might not be unreasonable - this is 70 year old specialized equipment, made in very low numbers And it might be just a component for a device made by another manufacturer.If I read that correctly, SEL was at one time in the top 10 largest german companies - so they manufactured a lot of stuff, lots of military and professional devices. The number might be a "Versorgungsnummer", a military part number.