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Re: [Amps] Alpha vs Henry

To: "'Roger (sub1)'" <sub1@rogerhalstead.com>, "amps@contesting.com" <amps@contesting.com>
Subject: Re: [Amps] Alpha vs Henry
From: Al Kozakiewicz <akozak@hourglass.com>
Date: Wed, 6 Apr 2011 20:38:39 -0400
List-post: <amps@contesting.com">mailto:amps@contesting.com>
Thanks.

You've reminded me that there is a blower speed selector in the cabinet and I 
should definitely make sure that it's running at the max for RTTY contests.

73

Al
AB2ZY 

-----Original Message-----
From: amps-bounces@contesting.com [mailto:amps-bounces@contesting.com] On 
Behalf Of Roger (sub1)
Sent: Wednesday, April 06, 2011 6:23 PM
To: amps@contesting.com
Subject: Re: [Amps] Alpha vs Henry

On 4/6/2011 5:05 PM, Al Kozakiewicz wrote:
> Can anyone tell me how much power an AL-1500 is rated to produce at a 100% 
> duty cycle?
>
> During RTTY contests and outputting about 1000 watts, the tube side of the 
> cabinet gets mighty warm.

It should.  Running 100% duty cycle and 1500 watts out at 60% efficiency means 
you are dissipating 1000 watts.  That is a LOT of heat. The temp of the exhaust 
air depends on how much air (CFM @ however many inches of
H20) the fan can push.  The 8877 is a relatively small tube for its ratings, 
but it has a fairly efficient radiator.  OTOH that means a blower that can 
produce a fair amount of back pressure is required to get full output from the 
tube.

As a comparison, when I had an all electric house I heated the basement and ham 
shack with 4400 watt space heaters mounted in the walls.  In the dead of winter 
it only took a few minutes to heat the 13 X 21' den to about 70 degrees. After 
that the heater would only kick on a few times for only a few minutes per hour. 
That means your amp running under these conditions puts out enough heat to 
require opening the den door to keep a reasonable temp.  IOW you could heat a 
good sized room with that amp on RTTY.

> The power supply side seems cool - but then, that's with the cover on.  I 
> don't know how hot is too hot and it would be useful to know at least how 
> much continuous power the supply is rated for.

If you were running large glass tubes that depend on radiation that cabinet 
would be too hot to touch.

73

Roger (K8RI)

> Tube cooling is probably another issue...
>
> Al
> AB2ZY
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