Antenna: JFET active attenna
@May 29, 2012
Cascade JFET amplifier
Input Resistance 1Mohm
Supply 9V-12V DC
broad band
Suitable for short vertical or mini loop
lack of band pass or SYNC with LO system, there are some "hissing" noise noticeable,in weak signal this will dramatically degrade the sensitive of the receiver.
Active whip antenna, the first version of active antenna based on VE7BPO's experiment:
Fig. Ant.1
How it perform?
@5/31/2012
There is no serious testing , just hear it , via my first SuperHet AM band receiver.
In door: pick up too much electronic noise with a 1 meter wire
out door: well good, strong signal might overload the first Stage IF AMP(no AGC)
broadband, AM to 3Mhz short-wave (higher frequncy not tested)
Improve the S/N: practical performance to use tuned circuit for input
There is a demo video, to show you how the tuned circuit make better receiver: more gain, more S/N. the Air variable capacitor connect and disconnect from the T1's primary to the GND, so a tuned load for Cascode amplifier added, too much improvement for the receiver.
@6/04/2012 Test Configuration: Antenna-C0, Mixer-J0, LO-H0