"Harold E. Johnson" ) writes:
"Highland Ham" wrote in message
...
Using polystyrene caps and with the VFO not having any buffer stage the
device fed by a 9v PP battery drifts not more than 20 Herz in 30
minutes.
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What kind of battery is a 9v PP battery? And, it would likely be helpful
to know what the Inductor is that the negative temperature coefficient of
the poly cap is compensating for. Is that drift specification for the
first 30 minutes after turn on or after the oscillator has been on for a
couple of days?
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A 9v PP battery is a standard battery pack , alkaline /NiCad / NiMH as
used in all sorts of consumer electronics incl battery operated smoke
alarm devices. Dimensions :45x25x17 mm. Available all over the world.
The battery is 'velcro-ed' to empty space on the board

And I assume that the PP means Peak to Peak.

No, it's the designator for the type of battery. Just like there used
to be "A Cells" and "B Cells". It's the common 9v battery, as he
explained. They are simply refered to as "PP" in Europe, just as
they have A4 paper over there rather than the 8.5 by 11 inch paper
that's common in North America.

Get out the ruler, and you'll find that his dimensions match the
battery in your smoke detector.

Michael VE2BVW