[Amps] AL-80A tube glow

[W5CUL]

Kim,

Just as a point of reference, I run an AL-80B with a Taylor 3-500Z.  When
running SSB, antenna ~1.2:1, driven with 50-60W, normal voice peaks stay
under 50ma Ig, power out is ~700 - 800W peak.  If I drive the amp such that
I push the Grid current to ~100ma during voice peaks, I will achieve ~1000W,
an additional 50ma of Grid will get me ~1100-1200W.  It is definitely a
logarithmic function, with the Grid taking the brunt of the burden in order
to squeeze out more wattage; not worth it if you want to make the tube last.


Mike
W5CUL
-----Original Message-----
From: amps-bounces at contesting.com [mailto:amps-bounces at contesting.com] On
Behalf Of Kim Östman
Sent: Saturday, July 07, 2007 2:10 AM
To: amps at contesting.com
Subject: [Amps] AL-80A tube glow

Howdy,

I've been using the AL-80A successfully (apart from some rare arcing  
inside) for about 10 years off and on, including contests.

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 SWRs on my antennas are below 2:1, 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.

Thanks in advance!

73 / Kim OH6KZP

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