[Amps] AL-80A tube glow

[Tom W8JI]

> 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 
radiation.

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