[Amps] 3-500Z plate durability

[jsb at digistar.com]

On Wed, 10 Dec 2003, Joe Isabella wrote:

> In my amp, when I transmit (espeically in the typical long-winded 350W
> carrier AM transmission), my RF Parts 3-500ZGs get quite red (almost
> orange).  After 1 year of pretty consistent use (abuse??) like this,
> they still run full output.

What's the grid current at that point - 80mA or thereabouts?  Plate
current?

I had a couple QSOs early this morning on CW and noticed that the plates
begin to show a faint bit of color near the bottom of the plates - the
tops near the cap stay gray.


I have to learn to be more careful though - i've been sloppy keeping the
grid current under 260mA when tuning.



> I think the BIG difference between these and the sweep-tubes you
> reference it is that they're just not transmitter tubes and aren't built
> handle it.

Must be - I should swap the filter capacitors out for new ones in the AC-3
and get that thing out of mothballs.  Then again, I like my Ten-Tec
Jupiter...  i'll let the Drake age a little more.



Thanks,
Jason