Mono CRT's testing and Aquadag

[AdrianPH]

I have been a bit daft and decided to do a long journey for 5 CRT's  in the hope that one will be a better screen for my Ferguson 991T.
Ebay item 294174803602. 

There appears to be two MW36-24 CRT's, a round tube, plus some?  Appreciate ideas, some could be re-gunned maybe.

I notice that one of the MW's has flaked aquadag, so did a bit of searching and found that one can buy it at around £4 for 100 g bottles but may only be for schools, something I may have to try and get around? I wonder if anyone can suggest a possible source that may be better if needed?

I will have to test the CRT's when I get them home all stand alone, heater continuity, cathode shorts should be simple enough and was thinking of the old style test between with a voltage between cathode and grid with normal heater voltages similar to Practical-Television-1964-06 CRT Rejuvenator.

Anyway Blackburn to Southend-on-Sea and back, I must be bl***y stupid.


Adrian

[boater sam]

If you can find somewhere to get crts re-gunned you will be one of the most popular people in the world.

[AdrianPH]

If I knew of a place to re-gun tubes I would not be doing this but would have my existing CRT done.

It could be a fools errand will just have to wait and see, will be going down next week. Who knows someone else may use some of them, I guess the round one is from an older bush 12 inch or so TV?

Adrian

[ppppenguin]

There is no CRT re-gunning happening anywhere in the world at the moment AFAIK. The ETF project in Ohio looks to be on hold. I've no idea what happened to the guys in Germany who were thinking about it.

[ppppenguin]

Google "conductive paint" to see a large variety of possible products to replace missing aquadag. I've no idea which ones will stick well to glass.

[Murphyv310]

Hi.

There "is" a re-gunner but outwith the EU in the former Soviet Union. Don't ask me any more as I don't know. Keep your eyes open on this forum as the info will come forth given time.

[AdrianPH]

I will be hoping that some of these are OK'ish they have been apparently in a loft space for some 50 plus years, I may get to find out a bit of history about them next week.

I have been watching the BBC news and thankfully the Blackburn area is not being held back in restrictions which was a concern. Will still be a masked visit when I go down etc.

OK on the google search terms, I will check things out when I get hold of them and if they test OK. I would appreciate your thoughts on the tests I am planning, I have copied a link to the magazine here: -
https://worldradiohistory.com/UK/Practic...964-06.pdf
It does not seem to be a heavy handed approach, it was well before colour screens and the higher currents indicated in them.

Adrian

[AdrianPH]

Around trip of 547 miles and I have 5 CRT's

There are two MW36-24's of which are of interest to me, I never remembered the sticky out final anode on my Ferguson.
A 17 inch Cossor which I believe is a 173K, I wonder if this would be a back-up for the 17 inch Murphy I have yet to attempt the V280.
An unlabelled 14 inch tube and
A circular tube 12.5 inch diameter at the screen outer that is a reworked tube by Nuvac I think the label says Mazda  either 122 or possibly 622, any other guesses?

All appear to have a heater resistance of close to 2.9 Ohm cold and no measure shorts when just using a DVM.  When I asked about the background of the tubes I was told they were found in Mum and Dads loft, a house they bought from someone that was a TV engineer.  So nothing of family interest to the seller.

17 inch pics
       

14 inch pics
       

Round CRT
           

Tomorrow will be me cleaning the pins and me checking emissions as above and comparing to the tube I have in my Fergy.

Adrian

[Murphyv310]

Hi.
The MW36-24 are now getting hard to find, nice little tubes with a good rectangular shape and my favourite by a big margin.
The gun in the Nuvac looks rather flaky unless its just the photo. A good regun can give very long service and excellent pictures. Nice load of Tubes you have got and even if one is totally no use don't throw them out as some museums are always happy to take them for non working display sets.
Have Fun but remember they are bombs in disguise, glass is "cooling" with time and can begin to deform with the load on them, make sure you wear goggles and protect your face, neck and arms. There are more stories of spontaneous implosions with older tubes so be careful.

[AdrianPH]

OK have played with the two MW36-24's my Fergy and the  14 inch tube with my test setup.

Test conditions are 6.3 Volt heaters with Cathode tied to heater  and a 290 Volt HT applied to the g1 pin via a 300 Kohm resistor and a 1 mA meter, I also use a DVM across the g1 and K pins to measure the diode potential.

First of all my Fergy 991T which uses the MW36-24 tube, when I connected the tester the emission was very slow to rise after around 30 seconds be 0.2 mA and slowly increased to just over 0.5 mA with a few minutes use.  The final diode potential was 131 Volts.
   

Tube A MW36-24 within 1 minute was at a diode potential of 6 Volts and very close to 1 mA current.
Tube B MW36-24 within 1 minute was at a diode potential of 48 Volts and current 0.8 mA.
The 14 inch tube diode potential at 16 Volts and close to 1 mA current.

I have not tried the 17 inch or round tube as I am trying to find data sheets to check heater voltages etc.  But it looks promising for the tubes to be reasonable, now to get some Aquadag.

Adrian