[TenTec] Centurion Amp Woes

[John K Gotwals]

I was intrigued by Rog's longevity recommendation for "Instant On" tubes, 
since I use a Drake L-4B amplifier. For ordinary tungsten light bulbs the 
bulb's life can be shortened by frequent turn-on/off due to the thermal 
expansion/contraction of the tungsten filament. In addition to the two 
3-500ZGs, my L-4B power supply has two series connected 50 watt bleeder 
resistors which get exceedingly hot while the power is turned on, and I 
would guess that thermal fatigue of these resistors might also be increased 
by frequent turn-on/off.

I would be interested in other comments on the turn-on/off vs. leave it on 
conundrum.

John, N9JG

-----Original Message-----
Message: 10
Date: Sun, 8 Oct 2006 15:26:45 -0400
From: "RB" <K9RB at bellsouth.net>
Subject: Re: [TenTec] Centurion Amp Woes
To: "'Discussion of Ten-Tec Equipment'" <tentec at contesting.com>
Message-ID: <070501c6eb0f$b1224dd0$0201a8c0 at k9rb8c670f7e81>
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[snip]
I also might suggest that with an amplifier using 3-500Z type "Instant On"
tubes, you will increase longevity of the tubes, as well as save on your
electric bill by turning the amplifier off whenever you do not anticipate it
use during the upcoming 10-15 minutes. Since the tubes require virtually no
warm up time, turning them off when not in use is a preferred mode of
operation. Just the 5 volts at 15 Amps of current to each tube calculates to
be 150 watts of wasted energy. Add the fan and HV transformer and you're
likely looking as 250 watts just in the standby mode that you have been
paying for, expended mostly in generating heat and contributing to shortened
component life.
[snip]
73, & Good Luck!, Rog-K9RB