Hi Doug,
Even though you didn't provide a definition of levels ("strong signal"
is subjective), your survey will probably point out an interesting fact
that many people don't know: with any rig that uses an class AB/B audio
amplifier, current drain on receive will go up when listening to very
strong signals, whether headphones or speaker are used.
It would be interesting to extend the survey to other transceivers, e.g.
NC20, RH40, SST. But in all cases, it will be comparing apples and
oranges unless the measurments of signal level are made *at* the load.
This is partly because some rigs may use series limiting resistors at
the headphones (the K1 doesn't).
In the case of the K1, I'd expect 55 mA average with no signal. With
headphones, it will probably be 55-70 mA, strongly dependent on what
"strong signal" level people choose, and on their chosen headphone
impedance. With the speaker, I'd expect 80-120 mA.
In the real world, current drain when using headhones will average very
close to the no-signal level. That's because average volume levels
incurred listening to ham signals are way below the peak volume levels
(if they weren't, you'd go deaf!).
So, you might ask respondents to note their *average* current drain over
some amount of listening time--say several minutes. I usually measure
current drain indirectly using a 1-ohm resistor in series with the power
supply, and set the DMM for millivolts, measured across the resistor. 1
millivolt = 1 mA. For long-term average measurements, I like to add a
2200-uF, 25-volt electrolytic capacitor across the rig's power-supply
terminals. This smoothes out the readings.
Results will be similar for all rigs that use LM380/386 and similar
audio amplifiers. If, like the K2, they use series limiting resistors at
the headphone jack, the volume control settings will be much higher for
a given signal level--you don't get something for nothing. This
highlights the need to define signals in terms of their measured AC RMS
or p-p voltage *at* the load.
73,
Wayne
N6KR
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