And todays mystery microwave object is.... - Page 1
Forum section: electronics / rf-microwave

author: davebullock
author_rank: Contributor
timestamp: April 01, 2025, 02:56:37 pm
content: Hi expertsScouring my boxes of valves today I came across this object from my early 23cms experimental days.I am not sure where it came from other than I seem to remember it was part of a set of 3 or 4 identical cavities all mechanically and electrically linked in series.Looking at this one (pictured) I assume it housed a 2C39 type valve and was tuneable?I have scoured the web to try to discover anything about it and failed :-(So.What was it's original use? (Military, Civil aviation, RADAR)What frequency does it cover?Does anyone have a link to any information please?It's a mystery I hope someone out there knows the answer to....Thanks in anticipationDave

author: LaserSteve
author_rank: Super Contributor
timestamp: April 01, 2025, 04:27:17 pm
content: Those used to show up in Hamfests in the midwest US My guess is L-Band IFF or Transponder. I was given one somewhat similar twenty or so years ago. Its long gone from my collection. Other then I have seen one, I have no details other than typically a 2C39.Steve

author: davebullock
author_rank: Contributor
timestamp: April 01, 2025, 04:44:10 pm
content: HI Steve,Yes several people have suggested that it may be an APX-6 unit but this IFF system doesn't look the same as the cavity I have. Also I seem to remember there were possibly 4 identical cavities all sat in a row with their tuning mechanisms 'ganged'. It appeared that the final 3 valves were a cascaded amplifier to get the required output power?The APX-6 just seems to have one main cavity at the TX frequency and the other valves are modulator etc.It's a mystery :-)ThanksDave

author: cvanc
author_rank: Frequent Contributor
timestamp: April 01, 2025, 11:24:07 pm
content: I won't guess the application, but could it be a socket/holder for a small klystron? (did they ever make klystrons this small?)

author: coppercone2
author_rank: Super Contributor
timestamp: April 02, 2025, 12:53:42 am
content: what does that component say that is soldered across the connector (black)?I think I see a X there, it looks like SIGMA-X-GCAN. you know what that might mean, greek navy?I think its time traveling byzantines

author: davebullock
author_rank: Contributor
timestamp: April 02, 2025, 08:01:30 am
content: The black inductor's legend saysPAINTONENGLAND2.0.FBut the again, the whole assembly is Greek to me :-)Klystrons..... three in series whatever for?I can't be the only amateur who has/had one of these, what is it?Dave

author: coppercone2
author_rank: Super Contributor
timestamp: April 02, 2025, 09:30:30 am
content: its not paignton?what the hell is painton. That's scary kinda, we forgot the name of a inductor manufacturer in only 60 years lol, hardly any recordshttps://www.gracesguide.co.uk/Paintonhttps://en.wikipedia.org/wiki/Plesseyits like geology, they slowly subduct or rather abduct companies

author: davebullock
author_rank: Contributor
timestamp: April 02, 2025, 09:55:20 am
content: More archaeology!I just traced the fellow radio amateur that I originally got me cavity off and incredibly he still had the RF pallet in his loft. See pic.It was roughly as I remembered with three of the identical cavities next to each other and in series.What I didn't know was that the it was made for the UK military (broad arrow) and by GEC.Described on the legend plate as an AMPLIFIER R.F. :-What was it used for?What frequency range?...andHas anyone ever modified one or more of these for use on 23cms?The mystery deepensDave

author: ftg
author_rank: Frequent Contributor
timestamp: April 02, 2025, 12:53:38 pm
content: The microwave museum by the UKµG folks does not seem to have anything similar.http://microwave-museum.org/exhibits/exhiblist.htmYou could ask on the UK Microwave operators groups.io list to see if anybody has converted them to 23cm before.https://groups.io/g/UKMicrowavesI don't think UKµG's Scatterpoint archives go far back enough to reach those days.https://www.microwavers.org/

author: joeqsmith
author_rank: Super Contributor
timestamp: April 02, 2025, 01:51:38 pm
content: Automatic tuner?Note the bolt pattern is similar to an old motorcycle carburetor.Did have have any of the internals that he could loan for a few photos?

author: LaserSteve
author_rank: Super Contributor
timestamp: April 02, 2025, 02:17:22 pm
content: With the exception of the last four digits, that is a US National Stock Number , FSC class 5840 comes back as Radar Except Airborne. 99-932 is a project managed by the United Kingdom. That is as far as I got. Slowly feed the string, incomplete at first, into one of the NSN lookup sites. An IF amplifier comes up as 5840-99-932-5115Note, it is not unusual for NATO Nations to buy each other's toys, share logistics, spread out manufacturing, have means for backup oddball emergency repair strategies, or share depot service paths, so toss out any nationalistic ideas as to its identity, use, etc.It's certainly not a carburetor. Might share an origin with a mechanical engineer who worked on gasoline engines at one time, but remember in the 50s-60s-70s, many Airborne things were piston powered, or if designed for a war emergency might have been made in a multi-purpose plant. A forming press is a forming press back then.Steve

author: davebullock
author_rank: Contributor
timestamp: April 02, 2025, 03:12:32 pm
content: Ah thanks for your replies.Well it's certainly NOT a carburettor and interesting that you found a military partial match for the serial number which sort of confirms it could be microwave RADAR related.Just to confuse me even more my contact has discovered a second label underneath the unit (attached).BTH now have a mention as well as GEC!Yes I looked on the Microwave group's museum site and drew a blank. So have lodged my question with their experts...Considering the serial numbers are 1575/6 there must have been a lot around. I am told this unit came from a well known UK army surplus store here in Nottingham.Surely others still exist and have been 'tinkered with'.Dave

author: LaserSteve
author_rank: Super Contributor
timestamp: April 02, 2025, 04:47:42 pm
content: You might want to enquire at Marconi Radar History, BTH-> Metrovick->AEI--> Marconihttps://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=&cad=rja&uact=8&ved=2ahUKEwjcgoiz5rmMAxXyMtAFHSd2LgkQFnoECAoQAQ&url=https%3A%2F%2Fmarconiradarhistory.pbworks.com%2F&usg=AOvVaw2yUUVv6eXVnyDkzZHykwL4&opi=89978449Steve