Left Coast Political Scene

Time to take a break from PNP Transistors and so a bit of a tour through Lauren Sanchez' boyfriends gift shop. This is a Touch Screen Display costing about $17 that plugs into a Arduino Mega 2560 -- it sure caught my eye. F inally, a dialing keypad (using the touch screen) I can actually see and work with my Fat Fingers. Don't know how complex the programming would be but imagine this as a front panel on a homebrew radio where you can tune and control your rig.  I have done it with a mechanical keypad, but this would be a different mouse trap. It makes the wiring a lot easier as it simply plugs into the Mega 2560. I find it refreshing that tools such as this are priced to be affordable. It is a great time for homebrewing. TYGNYBNT 73's Pete N6QW

Shown below is the Block Diagram for the 20M PNP SSB Transceiver steered in the  Transmit Mode . The components shown in the dotted block are relay steered so that the block module is single pass and amplifies in a single direction. The Block diagram show steered in Transmit.  Essentially the steering process works so that the IF Module input follows the Balanced Modulator on Transmit and then the input side follows the Receive Mixer on Receive. All done with some relays and a bit of RG174U coax. For those who count things in detail, this block diagram is not unlike what was used for the PSSST Transceiver which can be found on my website . Yes, a warmed over P3ST only using PNP devices. TYGNYBNT. 73's Pete N6QW

Hang in there as we soon will complete the PNP journey to develop a rig that employs PNP transistors throughout the topology. So far, we have presented simulations of the circuit modules which can be duplicated by blog readers using LT Spice.  Essentially, the 2N2907 and 2N2905 are doing the heavy lifting and we have identified a P Type MOSFET to replace the IRF510.  Today's post adds the 2N2907 Microphone Amplifier stage. This stage cranked wide open can deliver about 29 dB of gain over the speech range 300 to 3000 Hertz. You will not get glowing reports about speech at 100 Hz, but your signal will have a lot of punch for breaking pileups running QRP power levels.         By way of recap, we have: 1) A 2N2907 Microphone Amp 2) A 2N2907 and 2N2905 Audio Amp 3) Two 2N2907's in the IF Module 4) A 2N2907 RF Amp/Tx Pre-Driver 5) A 2N2905 Driver Stage 6) P Type MOSFET for the Final Amp 7) Two ADE-1's for the PD/BM and Rx/Tx Mixer 8) Si5351 + Arduino for the LO a...