I did that - terminated in 50 ohms.
73,
Steve, N2IC
On 03/16/2020 12:27 PM, Guy Olinger K2AV wrote:
Depending on the exact circuit and device, to measure noise from the device
itself, don’t you have to terminate the inputs to put the normal impedance on
them? The circuits are often designed with the coax Z zero in mind.
73, Guy K2AV
On Mon, Mar 16, 2020 at 12:47 PM Steve London <n2icarrl@gmail.com
<mailto:n2icarrl@gmail.com>> wrote:
This has been a very interesting thread - Thanks for all the input.
Perhaps I have set my expectations too high.
A typical application is on 15 meters, late in the opening, working JA's
from
here in SW New Mexico. Absent any local QRN, the band is very quiet. Any
local
noise covers the bottom layer of 5 watt JA's calling me.
I did some more testing with the MFJ-1025. With no antennas connected, the
box
raises the noise floor about 10 dB, irrespective of the Aux Antenna Gain or
the
Main Antenna Gain. I haven't yet tried powering from a battery, to make sure
the
power supply isn't the source. Assuming the J310's are quiet, that leaves
the
2N5109 emitter follower, or the back-to-back protection diodes. Might also
try
disconnecting the RF sense circuit.
73,
Steve, N2IC
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