FYI, since the genuine 2N5109 is so difficult to source (and the
2N3866), you might want to look at using a DCP68. This is a surface
mount device that will electrically replace the 2N5109 in the W7IUV
preamp provided you don't need to operate it at frequencies higher than
3 Mhz.
I have successfully used this device by simply soldering short leads on
the part and installing it directly in place of the 2N5109. You do need
to provide a heat sink of some sort. I have soldered the collector pad
down to a 3/4 inch square pad on an PCB and have also just soldered a
3/4 inch square, or larger, piece of copper sheet directly to the
collector tab.
The measured NF at 137 kHz and 475kHz is about 1 dB better than the 5109
and about 0.5 dB better on 1.8 Mhz. Best of all is that it costs less
than a buck and is available from most common distributors.
73,
Larry - W7IUV
On 10/22/2020 9:22 AM, Edward stallman wrote:
I remember about a year ago a discussion not to buy the 2n5109
transistors from E-Bay sellers . Some searching shows the 2n5109 has
been discontinued for many years . So is anyone that's been saving one
for many years willing to part with it ? I'm using it in a W7IUV pre-amp .
Thanks Ed N5DG
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