Don,
Thanks for sharing your research on the preamps. Very informative.
Your study is very timely for me.
I have ordered DX Engineerings new phasing box, NCC-2.
Optional plug in preamps are available for the unit. I am holding off
on ordering a preamp until I compare specs with other external
Hi JC,
I did not publish any absolute Noise Figure values, my measurements that I
published are all just differences in Noise Figure.
It actually is much easier to measure the difference in Noise Figure
between preamps that have such high gain (approximately 40dB in this case)
since the noise
Hi Don
Measuring noise figure below 1 db is a very complicated work.
First you need to remove all common mode noise, your noise floor should be
better than -135 dBm at least with a 40 db preamp connected to the radio
input and a 50 ohms load.
You need chokes everywhere and most important
Gary (KD9SV) kindly loaned me one of his 994 x5 preamps (sometimes called
KD9SV VLN (very low noise) preamp) so I could compare its Noise Figure
against one of my W1FB preamps as well as 2 of my W7IUV preamps in series
on 160 meters.
Here is a link to a youtube video I created that demonstrates
