I have Airam F40 from 70's that went eol some time ago. I thought breaking it so I could have it's cathode construction visible to put in display. What would be the best way to break the lamp in controlled manner that would keep the cathode and endcap most intact?

Why destroy it ? There is another way to show it through the intact tube

Make a very small illuminated point on one side of the tube. This can be done either with a Laser pointer + focussing lens, or with any very bright source (that could as well be the Laser) + a mask (Black card with tiny hole in it). The point light source will project an image of the cathode onto the other side of the tube. The smaller point of light, the sharper image you get

Well, I though I would destroy the lamp as it's eol and I would throw it to recycle point anyway. It's not that much collectable lamp as  I have much better speciments in my collection. I would also like to be able to show cathode without any additional equiptment.

EOL tubes are worthless and pointless in any collection, just my opinion though.  In fact.. unless it is an old incandescent bulb, no one will really care about a 10 year old fluorescent tube, much less an 80 year old.  That being said- wear long sleeve and pants clothing, hold the end you want to save in your hand (wearing gloves) and then take a hammer and hammer away above where you are holding, it should turn out ok.  Then you can flick away the glass shards remaining or use a pair of needle nose pliers to do it. 

I dont get why "Edison GLS" are considered collection pieces regardless of being EOL or not ? What is so special in them that does not exist with FL ?

The way i extracted cathodes from smashed tubes was to progressively hammer off the excess glass with small taps with a hammer untill i reach the end cap

Best way is wrap it in newspaper then tap GENTLY with a small hammer then carefully unwrap

I recently smashed a fish box filled with EOL T12's I brought 30 to the roof and just thew them off, I'm still finding glass schreds but it was worth watching the explosion with a friend and a beer.

We need to have a talk. 

Whenever I break fluorescent lamps it's usually me and friends having sword fights with the EOL tubes or "caber toss" them toward a wall or tree and watch the tube explode. It's always EOL lamps and always "eco" lamps, which have no collectible value to me.

I could care less about the environmental impact, I'm more worried about the safety aspect!

I could suggest something else that can be tossed to get a bang... Not the same, but without Glass everywhere

Take some small bucket or so (various food containers can do) of size about 5x5x5 inches. Fill with Water. Put in freezer for couple hours, in a way that the container is equally exposed to the cold from all sides (including from bottom) - best to put it on one of the grille shelves. Experiment with the freezing time, untill you get a block of Ice with about 1/2..1 inch thick walls (thick enough that they dont break when extracting the block from the container), but inside is still Water. As the Ice expands when it freezes (and the Water inside does not), there will be a big bubble trapped inside (where the Water is), possibly with negative pressure (have not chacked, but i suppose so ?). Anyway, those things also make a "pop" when they are tossed and smashed, and wet everything they hit

Nothing wrong with breaking glass out in the woods. There's already beer bottles from other people dumping out there (and we smash those too). And some people dump old CRT TVs in the woods. Those were really fun to crack open in high school. The glass is very thick.

You know, there is a boundary...

Mercury in lamps and small differences in Energy use of lamps and ballasts - the stuff greenies brag about - give me a break from that

Glass in lamps you break in the woods - Makes difference to the environment. The one in the immediate area. Wild Pokemon will get cut from it, if some piece of Glass is stuck in the wound they will try to bite it away and might ingest it, and get injured from inside

Peeps who break there bottles should be thrown in jail in their own right, what they do does not mean you gotta copy them. And whats more, the thin Glass from lamps is by far more dangerous than the thick pieces from bottles

Nothing wrong with breaking glass out in the woods. 

If its your own private property then fine (although I personally wouldn't do it because I don't want to clean up the mess )
If its public property, then not ok

Yeah but when wildlife cuts themselves on the glass as a result of our stupidity and bleeds all over the place.. well.. you know.