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Re: [Amps] AL-80A tube glow

To: Kim Östman <>,<>
Subject: Re: [Amps] AL-80A tube glow
From: "Tom W8JI" <>
Date: Sat, 7 Jul 2007 06:47:27 -0400
List-post: <>
> Something that I've paid notice to only as of late in the 
> 3-500Z tube
> is a gradually increasing orange or light red colored glow 
> in the
> metallic cooler wings(?) as one sends CW of SSB during an 
> "over". Is
> it normal for the tube to begin glowing like that, or is 
> something
> wrong?

The tube must show red on the anode or it will not degass. 
The gettering material in a 3-500Z is coated on the anode. 
Also the anode gets rid of heat primarily by infrared 

The lingering red you notice is probably thermal lag in the 
anode. It takes a while to cool after heating. If the idle 
current goes to zero on standby or to around 70-100mA 
between dots and dashes all is normal.

> The SWRs on my antennas are below 2:1,

SWR has nothing to do with anything except arcing in the 
tank loading capacitor or not being able to tune.

tube plate current around
> 450-500 mA (which I guess is stretching it a bit), and 
> grid current
> around 200 mA. Output according to a Daiwa meter is 
> between 700 to
> 1000 watts depending on the band.

The grid current sounds a bit high, like you could advance 
the loading control slightly more.

73 Tom 

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