3 Ghz Resonant Cavity - UK Vintage Radio Repair and Restoration Discussion Forum

Gridiron · 30th May 2018, 6:05 pm

Does anyone know what this was part of, possibly from a radar system or test gear for radar? The cavity is brightly plated and has a moveable piston controlled by a spindle. The cylinder on one side contains a CV285 diode valve, which is for use at 3 GHz.
Mike.

G6Tanuki · 30th May 2018, 6:12 pm

The construction style and connectorage does definitely hint at a military/avionics application, from the late-1940s or the 1950s.

[To be honest there would not have been anything using those frequencies in the 'fifties except for stuff like Radar]

Could it have been some sort of wavemeter? The small tubular stub on the right looks like it may have some sort of calibration-points on it, but the image is out of focus in that area.

Jon_G4MDC · 30th May 2018, 7:50 pm

Can be pretty sure it is a wavemeter, in the second picture a small coupling loop to the diode is clearly seen. The input cable (black co-ax) probably has something similar but it is out of shot and hidden by the cavity body, or it could just be a probe wire.

Most likely driven by a sniffer (or directional coupler - luxury) and used to confirm the radar rig was running where intended.

Silver plating is in very good nick for the age!

Gridiron · 30th May 2018, 10:26 pm

The two screws in the first photo are on an index which moves with the piston when the spindle is turned, there is one line engraved on this and one line on the body of the device which the index can be lined up with, no other markings or labels are on it.
Mike.

Julesomega · 30th May 2018, 11:08 pm

In its Pye-blue finish it looks like it could have been part of the 4GHz Wireless Set No. 10

Malcolm G6ANZ · 31st May 2018, 11:41 am

I've got one similar sitting in the garage. I rescued it from work where it was used to set the frequency of a pair of resonant cavities. The cavities were set to be just above and just below the resonant frequency of a clinical linear accelerator. The operation frequency of the accelerator was 2998Mhz. The output from the cavities was used to tune the magnetron the stay on the acceleratror's frequency. The accelerator having a very high Q factor the frequency was critical.
The vernier dial is calibrated in MHz. I beleive the whole device is silver plated.
The writing above the labelled 'input' says
"wavemeter type 1662 AM ref 10T/6089"

Malcolm

30th May 2018, 6:05 pm	#1
Gridiron Heptode Join Date: Apr 2010 Location: West Midlands, UK. Posts: 662	3 Ghz Resonant Cavity Does anyone know what this was part of, possibly from a radar system or test gear for radar? The cavity is brightly plated and has a moveable piston controlled by a spindle. The cylinder on one side contains a CV285 diode valve, which is for use at 3 GHz. Mike. Attached Thumbnails

30th May 2018, 6:12 pm	#2
G6Tanuki Dekatron Join Date: Apr 2012 Location: Wiltshire, UK. Posts: 13,995	Re: 3 Ghz Resonant Cavity The construction style and connectorage does definitely hint at a military/avionics application, from the late-1940s or the 1950s. [To be honest there would not have been anything using those frequencies in the 'fifties except for stuff like Radar] Could it have been some sort of wavemeter? The small tubular stub on the right looks like it may have some sort of calibration-points on it, but the image is out of focus in that area.

30th May 2018, 7:50 pm	#3
Jon_G4MDC Nonode Join Date: Nov 2015 Location: Welwyn Garden City, Hertfordshire, UK. Posts: 2,015	Re: 3 Ghz Resonant Cavity Can be pretty sure it is a wavemeter, in the second picture a small coupling loop to the diode is clearly seen. The input cable (black co-ax) probably has something similar but it is out of shot and hidden by the cavity body, or it could just be a probe wire. Most likely driven by a sniffer (or directional coupler - luxury) and used to confirm the radar rig was running where intended. Silver plating is in very good nick for the age!

30th May 2018, 10:26 pm	#4
Gridiron Heptode Join Date: Apr 2010 Location: West Midlands, UK. Posts: 662	Re: 3 Ghz Resonant Cavity The two screws in the first photo are on an index which moves with the piston when the spindle is turned, there is one line engraved on this and one line on the body of the device which the index can be lined up with, no other markings or labels are on it. Mike.

30th May 2018, 11:08 pm	#5
Julesomega Nonode Join Date: Dec 2012 Location: Stockport, Greater Manchester, UK. Posts: 2,102	Re: 3 Ghz Resonant Cavity In its Pye-blue finish it looks like it could have been part of the 4GHz Wireless Set No. 10 __________________ - Julian It's good here Last edited by Julesomega; 30th May 2018 at 11:11 pm. Reason: updating url

31st May 2018, 11:41 am	#6
Malcolm G6ANZ Octode Join Date: Feb 2006 Location: Bristol, UK. Posts: 1,041	Re: 3 Ghz Resonant Cavity I've got one similar sitting in the garage. I rescued it from work where it was used to set the frequency of a pair of resonant cavities. The cavities were set to be just above and just below the resonant frequency of a clinical linear accelerator. The operation frequency of the accelerator was 2998Mhz. The output from the cavities was used to tune the magnetron the stay on the acceleratror's frequency. The accelerator having a very high Q factor the frequency was critical. The vernier dial is calibrated in MHz. I beleive the whole device is silver plated. The writing above the labelled 'input' says "wavemeter type 1662 AM ref 10T/6089" Malcolm Attached Thumbnails