[1000mp] Re: Quadra Warranty

Sat, 18 Jan 2003 22:30:06 -0800

Hi Billy,

Sorry...you are right. I got my wires (grids) crossed, thinking that the
3CX1200A7 had a 4W grid-dissipation rating. I stand corrected.

Here are the grid dissipation ratings for some representative Eimac and
Svetlana tube types, from the data sheets:

Eimac: 3CX1200A7: 50W
3CX800A7: 4W
3CX400A7/8874: 5W
3CX1500A7/8877: 25W

Svetlana 4CX1600B: 2W (ouch!)

One can work around the problem of grid damage in a tube amplifier by using
a tough tube such as the 3CX1200A7or 8877 (25W is not bad). In a solid-state
amplifier, protection is not an option. Neither is ALC - it is the
amplifier's first, or only, line of defence.

Cheers for now, 73,
Adam VA7OJ/AB4OJ

-----Original Message-----
From: [email protected]
[mailto:[email protected]]On Behalf Of Billy Cox
Sent: Saturday, January 18, 2003 21:04
To: [email protected]
Subject: Re: [1000mp] Re: Quadra Warranty

>protection - as  do certain tubes with low grid dissipation ratings such as
>the 3CX1200A7. The "stuff" does not fail very often, either, I have been

Me thinks you meant the 8877 here ... not the 3CX1200A7 with it's
50 watt grid rating ... it's one of the tougher tubes ...

Now ... the 8874/8877/3CX800A7 series ... INDEED those tubes have
3 to 7 watt grids and need MUCHO protection circuits for those "Ah ...
heck" what did I just do times ...

Protection ... for solid-state or 'vacuum-state' amps brings a price
premium.

73 Billy AA4NU

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