[Amps] L7 Question

[ec1cwg@dxhunters.com]

Hi there,
I´m a proud owner of an old Drake L7 amplifier. It has been working out flawsely for 6 years here at my shack.
Just wondering what would be a reasonable period of time to heat it up before applying any load. Since first day I got this amp, I let it standing by for 5 to 10 minutes and then switch it for low voltage (1800V) and run it for a couple of hours at low power (500 wts) before take it to its full output limit (1Kw). No problems so far but a few days ago I talked to a fellow ham with same amp who advice me to let the amp heating up for an hour or so. For me this would be so much time but I haven´t found any details about this on the manual that´s what I would like to ask here if you think I´m reducing the life of my 3-500s. Thanks and 73s!
EC1CT Fernando
E-mail: ec1cwg at dxhunters.com