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August 26, 2024. The Complete IF Module using PNP Transistors

As promised the Complete IF Module using two 2N2907 Transistors. For 100 millivolts input we see 28dB of gain out of the module which says it will deliver 2.5 volts out of the module for that value of input. The maximum output is at 9 MHz.

[A quick math check reveals 20*log (2.5/0.1) = 28dB of voltage gain.]

In a similar module using BFR106's, I included 500 Ohm trim pots in the Emitter leg connected as a variable resistor so the whole module could be fine-tuned for the best, and most linear output. Since this amplifier module is steered and a single pass you get that same level of performance on both transmit and receive.

 

 

 



Upon close examination of the schematic, I have taken some liberties with simulating the crystal filter which is represented by two 500-ohm resistors connected with a 100nF capacitor. The real proof is to build the module and see how well the simulation predicts the performance.

Thus far we have PNP transistors in the IF Module, the combo Rx RF Amp/Tx Pre-Driver, the Driver and the P MOSFET Final Amp and lest we forget, the Mic Amp. We have as yet to come up with a PNP audio amp stage --- that may prove the most difficult.

So again, why are we doing this -- just because I haven't seen a complete homebrew SSB radio using PNP transistors in most of the block modules. Maybe one exists but I have not bumped into it other than what exists in the Sideband Engineers SBE-33 and SBE-34 designs. That was over 60 years ago.

TYGNYBNT

73's
Pete N6QW

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