[Tone Deaf]

Hi,

I'm building a cornet to be fully enclosed in a metal chassis (ie, no tubes poking through).  Has anyone tried this?  I'm fixing all parts on the reverse side of the board.  Some concerns now about heat & the life of electrolytic caps, specially around that 5Y3GT.  I've used 105 degree caps, but heat is not welcome I'd guess.
Also wondering if I'm likely to experience any problems with increased noise doing this, since the ground plane is not providing screening in this configuration.

Cheers

[Big Jim]

Are you enclosing the tubes to prevent people from touching them?

[SHIF]

I built mine like that, mounted all the parts on the back side of the pcb.  The board is mounted to the floor of my chassis on 1/4" stand-offs.  The finished unit can be seen at the very bottom of this web page:
http://www.hagtech.com/diyer.html

My enclosure was just tall enough to cover the tranny. I machined a 2" dia hole in the lid so the 5Y3 could just stick up but not through. Also lets heat out.  I also cut slots above the board and in the floor so I get passive cooling.  The slots are a design feature and look nice too.  I put a tiny blue LED in the middle of the front end to remind me the unit is on.

My Cornet has been running without issue for over three years!

-S

[Tone Deaf]

I've had a Cornet built in the standard way for a good while, & thought I'd damaged the board while changing parts.  As it happened, it was alright & I repaired it.  But in the meantime I'd bought a new board, so fancied building something different, & hopefully more compact. 

Shif, your unit looks incredible.  Mine won't be so attractive, or unusual, just the usual aluminium tin!  How hot do things get in there?  I'm using a perforated base plate and will drill holes above each tube - hope that'll be enough.  I've got a EL34-sized pearl cooler to wrap round the rectifier as well.

Intention is it that it'll be switched on/off by an aux power socket on the preamp, but with a switched inlet on the back just in case.  I'm thinking of adding on the bi-color LED circuit from the cornet 2 as an on indicator.

TD

[SHIF]

...How hot do things get in there?  I'm using a perforated base plate and will drill holes above each tube - hope that'll be enough.  ....

TD, The innards of my Cornet don't get very hot, even after several hours of continuous operation.  I have rubber feet on the bottom to achieve air space beneath the unit. With perforations in the bottom and holes in the top you get automatic cooling as the hot air escapes out the top drawing room air in the bottom.  It's not much flow but obviously enough.  My Cary preamp and CDP both have internal tubes as well with even fewer vent holes than my Cornet, still no heat related issues.    -S

[Tone Deaf]

Thanks Shif.  Confidence is restored!
TD