Rumors abound that you can broadband the receiver of a Uniden 1978-made SSB CB radio with a simple trick.
Pretty sure this is what they mean. Don't have a clip of the schematic, but we're changing where one pin of one transistor in the receiver gets its input signal. The factory connects one gate of FET1 to a tap partway down the output winding of L4. This trick moves the transistor's gate input to the top of this winding, where the signal voltage will be higher, and the circuit Q will be lower (more broadbanded).
First, let's find L4 on the solder side of the board.
We're interested in the three pins of L4 on the left here, the top two are soldered each to a foil pad, and the lower one has no connection, just sticking out of the bare laminate.
First step is to string a thin wire from that unused pin to the gate pad of FET1. This keeps the gate of FET1 from being an open circuit, not connected to anything. This can be a hazard for 1970s MOSFET transistors. If we cut the foil trace as you see below first step, the transistor's gate pin would "float", connected to nothing.
Last step is to cut the original foil trace to the center pin of L4.
Carefully.
L4 will have to be realigned, and you'll see that the peak on the slug of this side of L4 is not so sharp as it was before.
Your mileage may vary, but this trick has worked for us for a long time.
73
Pretty sure this is what they mean. Don't have a clip of the schematic, but we're changing where one pin of one transistor in the receiver gets its input signal. The factory connects one gate of FET1 to a tap partway down the output winding of L4. This trick moves the transistor's gate input to the top of this winding, where the signal voltage will be higher, and the circuit Q will be lower (more broadbanded).
First, let's find L4 on the solder side of the board.
We're interested in the three pins of L4 on the left here, the top two are soldered each to a foil pad, and the lower one has no connection, just sticking out of the bare laminate.
First step is to string a thin wire from that unused pin to the gate pad of FET1. This keeps the gate of FET1 from being an open circuit, not connected to anything. This can be a hazard for 1970s MOSFET transistors. If we cut the foil trace as you see below first step, the transistor's gate pin would "float", connected to nothing.
Last step is to cut the original foil trace to the center pin of L4.
Carefully.
L4 will have to be realigned, and you'll see that the peak on the slug of this side of L4 is not so sharp as it was before.
Your mileage may vary, but this trick has worked for us for a long time.
73
