The K3 PA is the original module, but I don't know what devices it uses.
Perhaps someone with inside knowledge could provide a S/N range or
approximate date for the changeover. I built my K3 from a kit in July
2009. As I recall, It draws about 17.5A with key-down CW on 20 meters.
The K3S PA module was replaced in July 2016. I don't know if the
original K3S PA showed the elevated current draw before it was replaced.
73...
Randy, W8FN
On 9/6/2020 2:07 PM, ab2tc wrote:
Hi Randy,
Does your K3 #3260 have the newer MOSFET PA? I believe the K3 switched the
PA from bipolar to the newer MOSFET design at some point (mine is #82!). I
agree with you that the 20/30m LPF ought to be a prime suspect. Everything
else is common and 14MHz should be very close to the center of the total
frequency range of the transmitter. My K3S has not had any reliability
problems either, but it sees fairly light duty with SSB only and no heavy
duty "run mode" contest use.
BTW, I checked the current draw on 30m (on the K3S) which *shares the same
LP filter*. It is an average 17.5A. But 30m is lower in frequency and thus
farther away from the filter cutoff. 40m, 15m and 10m LP filters are also
shared with a lower frequency band, but do not cause an elevated current
draw.
Knut - AB2TC
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