On Jun 27, 2006, at 11:22 AM, Tom W8JI wrote:
>> It says it on page two of the Eimac 3-500Z spec sheet. See
>> the one the link was provided for earlier.
> Single tone carrier level has absolutely nothing to do with
> operation in a different set of conditions such as two-tone
> modulation at a different anode voltage, bias, and power
> level. You are reading more into the data sheet than it is
As I see it, no matter what kind of modulation one is trying to
amplify, at the point when an incremental increase in input no longer
increases output (which call the transfer function) by the same
factor as was observed at lesser currents, the cathode is running out
steam and the tube is beginning to lose linearity. Even though there
is a 3a line on the 3-500Z/ 8002 characteristic curves, does this
mean that all will be well in linear service at 3 peak anode
amperes? If this were the case, at 4kV, single 3-500 linear
amplifiers could produce 2500w PEP.
OTOH, Tom may be right in saying that tuning up at 550mA produces
good linearity in an AL-80 or SB-1000, but from the impure matter I
hear from these two amps on the air that are driven with 100w, I have
> For a given set of tuning conditions (load line) a person
> can make the single tone level any level he wants by varying
> drive and the two-tone test will remain the same as long as
> the two-tone power level isn't changed. Single tone and
> two-tone are two totally different conditions, and as the
> data sheets say other operation is permissible.
But there can be no help if the cathode is running out of emission.
> Two other random people
What are their callsigns, e-mail addresses, and telephone numbers?
> besides myself have now posted that
> the did the equivalent of a transfer function (which is what
> really measures linearity) and both posted the best
> linearity when the steady-state loadline was established at
> about 550mA.
I don't see how because 550mA corresponds to c. 1650mA peak, which is
well into the non-linear region.
> Actual performance under one set of conditions
> cannot be determined by extracting data from a test under
> totally different conditions.
Peak emission capability is negotiable?
> 73 Tom
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