EQUIPMENT BACKGROUND
After years of use and then storage once the analog Teletext television system was turned off yonks ago, I have finally gotten around to placing this professional, very well built equipment onto the workshop bench ... the "operation" has begun
This equipment was fully functioning but of no possible further use in our digital television (with no teletext broadcasts) era so now I have extracted components and modules "of interest" which can be used to restore another EH-1000 or possibly suit use in other "dated" equipment such as another vintage oscilloscope or waveform monitor.
Another possible use is for educational purposes, showing how the electron beam is generated (the inside elements are easily viewable), focused, deflected in the X and Y domains and then accelerated, possibly being rotated before finally striking the inside of the phosphor coated front glass face.
Now it's time to take out the scalpel and start the op!
One the of the first things to note is that although this is branded Unaohm and manufactured in Italy, the components inside have been substantially sourced from European and English component manufacturers, the likes of Siemens and Philips.
THE DONOR EQUIPMENT
UNAOHM - Teletext Video RF Analyser
Model: EH-1000
Designed & manufactured in Milano, ITALY
Circa Late 1980's (based on advertisements placed in Wireless World at the time and the date stamp on the AC transformer core)
Technology: Analog video broadcast signal analysis - specifically for examining lines of Teletext information "riding along" with the video signal
Luggable (heavy at 15kg) due to the heavy duty Aluminium outer case but more importantly, the inside welded steel frame chassis inside.
Well engineered inside, logically laid out using a number of modules which are well interconnected.
Designed for 220V 50Hz operation (because of this, we used this equipment via an AC variac many years ago)
Green emitting rectangular CRT based front panel display
Interested in the technical nitty gritty? Here is an old copy of the spec sheet
Enough information about the "patient" now to the component(s) I have removed
CATHODE RAY TUBE (CRT)
Unbranded - I strongly suspect this is an English made product but I cannot find any references to the manufacturer of the tube nor it's part number. Often these used a paper stick-on label and perhaps this label "fell off" sometime. I can see a coding "string" stamped on the metalwork INSIDE the glass tube but this seems to be a strange place to put the component part number.
The surrounding magnetic shield though IS marked with the manufacturer, being ...
MAGNETIC SHIELDS LTD
STAPLEHURST, KENT
ENGLAND
CRT technology: Electrostatic deflection
This means that the positioning of the electron beam is undertaken by both an X and a Y plate system INSIDE the tube, there is NO deflection yoke involved. Oh yes, there is a single coil on the tube but that is used to rotate the electron beam.
Face shape is rectangular, measuring 100mm height x 120mm wide EXTERNALLY
Actual display area (with the phosphor) measures 86mm x 105mm
Phosphor emission colour: Green
Persistence of the phosphor is unknown but it must be fast as this was used to display "live" television broadcast signals and no blurring occured while viewing.
Supplied complete with the custom fitting magnetic shield and front mounting brackets plus the rear 12 pin CRT female socket with previous wiring from the EH-1000 remaining intact.
The magnetic shield enclosure tests positive for ferrous, it is Iron based. I wondered if it was Mu metal but I don't think so.
The anode cap is NOT supplied, that is part of the power supply module and will be advertised separately.
A note about the anode connection, unlike many tubes, this CRT uses an pin that extends outwards for connection to the anode cap, meaning that a "normal" anode cap (as used on other CRT's) may not fit properly. I do have the correct anode cap but it is part of the power supply module which is being advertised "soon"
CRT DIMENSIONS
Total dimensions of the complete unit, with the magnetic shield: 335mm length x 124mm height x 123mm wide
The front rectangular face is flat, not curved, and a very thick glass at 7mm
WEIGHT: 1.6Kg
TESTING:
Known to be fully functional and in regular use but that was quite some time ago (see one of the photographs showing the CRT displaying live television - although it is not a great photograph that I took!)
I have not rechecked this component lately, although it has always been carefully stored, as it simply wasn't practical to do this now.
COSMETIC CONDITION:
USED
CLEAN
NO damage to either the shield or the glass CRT (Handle with care!)
NO damage to the Anode side connection pin
NO damage to the "rotation" coil
NO damage to the nylon CRT female 12 pin socket
NO scratching to the gun neck or the front face
The CRT sits inside the magnetic shield, supported by foam pads and at the gun neck there is an internal metal ring which "grabs" the tube neck and ensures that the tube stays safe n sound inside. You may notice the tape wrapped around the neck ... that is where the metal ring clip inside the magnetic shield grips the tube neck, that tape is to cushion the meeting between metal and glass!
SPECIAL NOTE:
I have carefully reassembled the CRT so that it sits nice and safely within the outer magnetic shield BUT then realised that I have left the rotational coil wires INSIDE the shield and reversed the fitting of the CRT inside the shield! - this means the Anode pin is not externally accessible at the moment.
Doh! Old persons moment!
To use this CRT, carefully extract the tube from the magnetic shield (it's an easy process) and rotate before reinserting, plus make sure those coil wires are also available externally.
The CRT has now been "put to bed" within copious amounts of bubblewrap and a strong outer cardboard packaging to ensure it does not get damaged when shipped.
