a low pass filter
use this Low pass filter
for this QRPp
a QRPp transmitter
To build this 10m QRPp transmitter I'll need the folowing components.
SG531PT transmitter intergrated circuit (IC).
A Low Pass Filter (LPF) to keep it RF harmonicely clean.
The LPF requires 2 0.33uh RF chokes,
2 ea 100pf capacitors and
1ea 180pf capacitor
A bypass capacitor of .001uf is also required.
A telegraph key is also needed
I'll use a normally open (NO) push button switch
Mounted a BNC connector on some copper substrate
Built the LPF on the copper substrate
using manhattan construction technigues
Added the SG531PT IC
Added the switch that is used as key
Grounded pin 4 and installed the bypass capacitor
+5vdc line from key installed
+5vdc will be applied here.
A +5vdc voltage regulator has been installed it has an outputof 5.05vdc.
A +5vdc voltage regulator has been wired into the transmitter.
When transmitting into a dummy load and measured on a DMM
it shows a voltage o f 1.048v RMS approx 150mW.
The TRANSMITTER TEST
IT WORKS A REAL QRPp TRANSMITTER