August 29, 2024. The PNP Microphone Stage

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 and BFO

Yes, you guessed it still to come a block diagram and a recap posting of all of the circuit simulations.

See that was not too bad so now back to all of those mysterious menus hidden behind the ICOM IC7300 buttons.

TYGNYBNT

73's

Pete N6QW

January 26, 2024. A simple CW Transceiver/Transmitter

Cruise through the lower part of the ham bands bands and what do you hear? Well, FT-8 and CW. Often you will not hear any SSB stations yet go to the lower part of the bands, and it is a cacophony (I love that word) of bad sounding signals and some high-speed keying. Fast is not so much of the issue as is bad, run together and jerky keying. But none the less our hobby started there. So, you could crank down your ICOM 7300 and watch the waterfall on CW or you could homebrew a radio. Actually, to do CW right you need more thought up front than you do with a SSB transceiver. Often, I will state that a CW Transceiver is much more difficult to build than a simple SSB rig. I published two articles in QRP Quarterly on CW transceivers and all I got was a yawn so maybe history will repeat itself. Yawn! 30M CW Transceiver with RIT! Of interest is that the LO is a Varactor tuned LC oscillator using a NE602. Look closely at the RIT circuit which is only activated on ...

March 31, 2024. Happy Easter to those who celebrate this day.

What a great day to Binge on Chocolate and experience the pain of that filling that has been leaking. I would be in that category with the leaking filling(s) had I not just spent an amount equivalent to one of the fancy new uptown appliance box transceivers on two filling repairs. Well at least I can binge on the Chocolate bunnies without fear of pain. Regrettably everything appears to have jumped in price including the price of parts. Well not so much the parts as the shipping costs. That notably is seen in the eBay treasures. I spotted a nice heathkit DX-20 for about $50 and the shipping was $65. Likely it is a twofer with part being a way to in effect charge a higher price by inflating the shipping and in part by increased shipping costs. Shipping with insurance across the US was about $150 for this jewel and that was three years ago. 6AM on the Left Coast ~ 20M Easter Sunday! My only hope is the cost of Chocolate Bunnies remains steady although a pound of See's Candies f...

August 30, 2024. A PNP 20M SSB Transceiver

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

Pay More and Get Less. Flash the Cash!

Search This Blog