Re: Accuracy re fidelity on/with the TX display while using PS
Posted: Sat Feb 24, 2018 5:36 pm
Rob
Yes... doing this measurement with an auxiliary receiver in the same location as one's transceiver/amplifier is much more complicated than it appeared to be when we first thought about it.
Even with the relatively low internal crosstalk levels in the more recent ANAN-XXX products, I remain skeptical of actual amplifier output IMD improvements (i.e. with Pure Signal on vs. Pure Signal off) that are much larger then 20dB. [Note that a 20dB IMD improvement is still very significant].
A recent measurement on 20m:
ANAN=10e output: 4W Elecraft KXPA100 amplifier output: 100W
Measurement 1: Amplifier on (100W output), ANAN output 4 W, amplifier feeding a dummy load, the Pure Signal input of the ANAN-10 is obtained from a home-brew coupler at the output of the amplifier . S-ATT reading: 26, Panadapter reading: +12dBm
Measurement 2: ANAN-10E output switched from the amplifier input to a separate dummy load using a DPDT coaxial relay. At the same time, the amplifier input is connected to a third (separate) 50 ohm termination, and the Pure Signal input to the ANAN-10E is connected to the same home brew coupler, at the output of the amplifier, as in measurement 1. S-ATT reading: 26, Panadapter reading : -18dBm.
Contrast = +12dBm - (-18dBm) =30dB
Stu
Yes... doing this measurement with an auxiliary receiver in the same location as one's transceiver/amplifier is much more complicated than it appeared to be when we first thought about it.
Even with the relatively low internal crosstalk levels in the more recent ANAN-XXX products, I remain skeptical of actual amplifier output IMD improvements (i.e. with Pure Signal on vs. Pure Signal off) that are much larger then 20dB. [Note that a 20dB IMD improvement is still very significant].
A recent measurement on 20m:
ANAN=10e output: 4W Elecraft KXPA100 amplifier output: 100W
Measurement 1: Amplifier on (100W output), ANAN output 4 W, amplifier feeding a dummy load, the Pure Signal input of the ANAN-10 is obtained from a home-brew coupler at the output of the amplifier . S-ATT reading: 26, Panadapter reading: +12dBm
Measurement 2: ANAN-10E output switched from the amplifier input to a separate dummy load using a DPDT coaxial relay. At the same time, the amplifier input is connected to a third (separate) 50 ohm termination, and the Pure Signal input to the ANAN-10E is connected to the same home brew coupler, at the output of the amplifier, as in measurement 1. S-ATT reading: 26, Panadapter reading : -18dBm.
Contrast = +12dBm - (-18dBm) =30dB
Stu