Since the entire country is on Coronavirus lockdown at the moment, I figured it was time to get round to finishing off a couple of small blog posts while waiting for the restrictions to be lifted 😉
This is a small two-stage linear amplifier module available on eBay fairly cheap for SDR operation.This unit claims 3W (34.8dBm) power output at 0dBm input, however not surprisingly, this amplifier isn’t quite flat across the frequency range.
Here’s the readout from an R&S FSV7 spectrum analyser. The amplifier is being driven from the analyser’s tracking generator at 0dBm, and the output is fed back into the input via 60dB of external power attenuation. The span here is 1MHz-1GHz, and at the top end the frequency response is already beginning to drop off a cliff – the 1GHz rating appears to be the 3dB down point. The rated output power of 3W appears to only be attainable below 100MHz for the rated 0dBm input, after that it drops pretty quickly to about -3dB.
| Frequency | Output - dBm | Output - W |
|---|---|---|
| 100MHz | 34.74 | 2.97 |
| 144MHz | 34.4 | 2.75 |
| 200MHz | 33.81 | 2.40 |
| 315MHz | 32.59 | 1.81 |
| 433MHz | 31.46 | 1.39 |
| 500MHz | 30.91 | 1.23 |
| 600MHz | 30.87 | 1.22 |
| 700MHz | 31.04 | 1.27 |
| 800MHz | 30.95 | 1.24 |
| 900MHz | 30.24 | 1.05 |
| 1000MHz | 26.86 | 0.48 |
Extending the frequency span of the analyser shows the roll off at high frequency – this module really isn’t usable above the rated frequency range.
They ground off the part numbers of the RF transistors on the unit I purchased. Do you have any idea what the part numbers are? I’m thinking that if I damage the unit, I could replace the damaged output transistor.
Le transistor et un Mosfet (RD01MUS1) markage K2 ou (RD01MUS2) markage K5 les deux les identique sauf la tension VDSS