14-4-2018 updated
Above the low noise preamp 50 - 4GHz ebay 6€
Tested 2 small porto antennas
1 Baofeng UV antenna left 2nd best signal on PI2NOS
2 eBay DIAMONDSRH805S wide band 144/432/1200 it works for its size as expected
3 piece of wire : best signal in the setup...
Unit under test at workbench.
It was stable 50mA at 5V few days, but sudden the current went up to 100mA
And i could no longer adjust it with the negative bias Voltage.
The - Voltage went to zero and the SPF input port became low Z.
This SPF5189z was broken no oscillations, no input overload just it broke while i was receiving the PI2NOS 430.125 using a small antenna at the workbench.
The specs of SPF5189z say it has an internal circuit regulating the bias current.
Replaced . again with an other of the 5 spare SPF i have.
The new one again could be adjusted at 50mA 5V
The current raises to 150mA when removing the negative gate voltage.
Where is that internal bias circuit ?
I suspect eBay …
Above the low noise preamp 50 - 4GHz ebay 6€
Tested 2 small porto antennas
1 Baofeng UV antenna left 2nd best signal on PI2NOS
2 eBay DIAMONDSRH805S wide band 144/432/1200 it works for its size as expected
3 piece of wire : best signal in the setup...
Unit under test at workbench.
It was stable 50mA at 5V few days, but sudden the current went up to 100mA
And i could no longer adjust it with the negative bias Voltage.
The - Voltage went to zero and the SPF input port became low Z.
This SPF5189z was broken no oscillations, no input overload just it broke while i was receiving the PI2NOS 430.125 using a small antenna at the workbench.
The specs of SPF5189z say it has an internal circuit regulating the bias current.
Replaced . again with an other of the 5 spare SPF i have.
The new one again could be adjusted at 50mA 5V
The current raises to 150mA when removing the negative gate voltage.
Where is that internal bias circuit ?
I suspect eBay …