>I recently picked up a very mint AL80A with a nearly dead tube. After some
>research I discovered that the Amertiron manual contradicts what Eimac
>published in their data sheet for the 3-500Z. Or am I in error?
>
No
>Page 4 of the AL80A manual step 12 reads"Apply enough drive to indicate
>either 1000 watts of output power or 200 mA of grid current. Re-peak the
>LOAD and PLATE controls. The grid current must not be over 200mA, the
>plate current over 550mA or the output over 1200 watts."
>
>My Eimac 3-500Z spec sheet states that for class AB2 cathode driven max dc
>plate voltage is 4kvdc, max Ip is 0.4 amps, plate dissipation is 500
>watts, and grid dissipation is 20 watts.
>
This is what my spec. sheet says, Lane.
>How does the operator achieve "1000 watts of output power" out of an amp
>running a single 3-500Z at an Ep of 3100 vdc??
To obtain 1000w of output power in linear service, a higher supply
potential than 3100v would undoubtedly be needed.
> Isn't 200mA on the grid kinda high for a single bottle??
I doubt that it would damage the grid.
>What about 550mA of Ip??
>
Fantasyland. When driven to 550mA, a 3-500Z is undoubtedly not linear.
However, overdriving the tube would not be likely to shorten life. The
most common life-shortener is either too much filament voltage, or a bent
(fil.-grid shorted) filament helix due to intermittent VHF instability.
If the tube has low emission, it might be interesting to measure the fil.
potential at pins 1 and 5 on the tube socket.
>I am trying to prevent these same problems from re-occuring. The previous
>owner is an old time ham who bought a new AL-82. The problems with the
>AL80A don't seem to be the amp but they seem to be the INSTRUCTIONS.
>
. The person responsible for writing those instructions claimed that he
has a letter from Eimac confirming the higher Ip (anode current) rating.
I asked him to post the letter. If you guessed that he did not,
congrats.
>Comments and opinions most welcome. I am not an "old salt" when it comes
>to these amps but something doesn't jive.
Indeed. Some people are apparently better able to deal with reality than
others.
- later, Lane
Rich...
R. L. Measures, 805-386-3734, AG6K, www.vcnet.com/measures
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