Hi everyone.

I'm having a look at some aspects of tubes and valves (their glow is mesmorising!), but their is something I'm unsure of.

Are there many equivalents of CRTs/valves?

For example, one could swap a NE555 and an LM555 and could get away with it.

Is this still the case, or should valve and tube numbers be obeyed strictly?

The reason I'm asking is that I'm looking into making a little project with a 2AP1 Cathode Ray Tube, but I'm finding it hard to find. Is there an equivalent I could simply switch, or would the circuit need to be changed?

Thanks very much for your time, with every post I learn a lot!

Sparky

 

Have a look on this page:
http://www.myvintagetv.com/vintage_test_equipment.htm
There are a few units that use the 2AP1. No, they're not for sale, but you will have an idea about their size, etc. 2" diameter is pretty doggone small; that's about the diameter of the SAM (surface to air missile) warning display we had in our F-4 Phantoms back in the '70's.

You might be able to substitute a different CRT, but you may have to make changes, as you're afraid of. Antique tubes like that will be difficult to find, so you'll have to "make do".

While old diode/triode/pentode/etc tubes/valve documentation is easy to find, it's more difficult to find CRT documentation - as tubes/valves were used in just about everything years ago, but CRTs were application-specific.

If you are trying to make something like an oscilloscope or spectrum analyzer, you will need that type of CRT that has the deflection plates internal to the neck. The amount of deflection is small, but the deflection occurs very quickly; necessary for low response times - you won't be able to substitute a CRT from a television set. A TV set uses an inductive deflection yoke, and the response time is very slow in comparison.

'eta'
Have a look at this page:
http://www.electronixandmore.com/project/7.html
Not sure how useful it will be to you, as it's mainly about CRTs that were used in the States - but it might give you some ideas.

More on the tube you're interested in here:
http://www.radiomuseum.org/tubes/tube_2ap1.html

 

Hello,

On the following pages you will find a lot of information on tubes:
http://www.nj7p.org/Tube4.php?index=1
http://greygum.net/sbench/sbench101/

The EDUCYPEDIA has also a page with a lot of links:
http://educypedia.karadimov.info/electronics/tubesdata.htm

Bertus

 

Wow, thanks for the information guys.

Sgt Wookie, thank you very much for taking the time to write such a interesting reply. I had no idea you worked with Phantoms! Up until a couple of weeks ago, there was an RAF Phantom as Gate Guard near where I live. If I remember correctly, didn't the US use them on aircraft carriers?

Thankyou for the links Bertus, that EDUCYPEDIA has alot of interesting articles.

 

Wookie, I was going to have a bash at the tube version on that page - great minds think alike eh?

I wouldn't like to ask a lot, but could you give point me in the right direction for a simple (ish) project - hopefully with a more readily accessible CRT?

Thank you.

 

Too bad you don't live closer to me; I've got one in my garage that you could have.

Or you could try eBay; I just saw one offered for sale at US $15.

 

Sgt Wookie, thank you very much for taking the time to write such a interesting reply.

My pleasure.

I had no idea you worked with Phantoms!

Yes, F-4J's and F-4S's. The F-4J's were updated/reworked to become F-4S's; my squadron got the 1st batch of the F-4S's assigned to the Marines. The Navy and the Marines flew a lot of these. They started being replaced with the F/A-18 Hornet in the early part of the 1980's.

Up until a couple of weeks ago, there was an RAF Phantom as Gate Guard near where I live.

I wonder what they did with it?

If I remember correctly, didn't the US use them on aircraft carriers?

Yes, both the Navy and the Marine Corps.
I was deployed on the USS Forrestal (CV-59) in 1976. That ship was the first "supercarrier".
It was retired in 1993.

 

I wouldn't like to ask a lot, but could you give point me in the right direction for a simple (ish) project - hopefully with a more readily accessible CRT?

I'm afraid you're inquiring on the wrong side of the pond, as I don't even have a feel for what's more common even in the States, much less the UK.

Seems to me that the UK has the equivalent of the ARRL (American Radio Relay League) over there. Those are the people you want to get in touch with, as they will have many connections for obtaining odd bits to build/keep equipment running - and will have a far better idea of what was available in the UK in the past.

 

Hi Sparky. Heres a circuit of a CRO from the 60s for home build 3 inch. If you want more I have the whole article.

 

Hello,

For old books with tube schematics have a look here:
http://www.tubebooks.org/technical_books_online.htm

There is also a section for measuring equipment, see here:
http://www.tubebooks.org/technical_books_online.htm#Test & Measurement (equipment, instructions...)

Bertus