Topband: Looking for a 2n5109

[Larry]

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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