[Amps] Alpha vs Henry

[Al Kozakiewicz]

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 at contesting.com [mailto:amps-bounces at contesting.com] On Behalf Of Roger (sub1)
Sent: Wednesday, April 06, 2011 6:23 PM
To: amps at 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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