OLD RF AMP NO AGC


The two transformers was ripped from a dead AP700 radio 10.7 if amp.
20 turns 0.15mm cu, then I have added the 2turns 0.22mm cu.
The coil is sealed in a small alu case,
the two transformers must be located a bit away from each other, to prevent feedback.
I guess any N-FET Dual gate will work, 3N141, 3N211, BFR84, 40673 I have tested this amp with a TA7153
Just use what you can rip from dead recievers..


This Amplifier:
Gain = +27.5 dbm
If not mounted (C3), the Gain drops to + 13db
Zin = 50 Ohm
Zout = 50 Ohm
Fmin = 14.0 -3db
Fmax = 14.3 -3db
Current = 1.7mA @ 12Volts
Max input level -10dbm gives +17dbm output
More input will not damage the amp, but output will not give more than +20dbm
Noice = I can't measure it, can't see if the amp is on or off with the best I have !!

To change the band-width just add a resistor (4K7) over the 20 turn coil use equal value on input and output transformer.
This will also degrade Gain.


The to 20 turn vindings before the 2 turns was added on top.

See how the RF-Amp is done in the new design with AGC input

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