How to spend the time we have left this year? Well, we could glue a TV set to our eyeballs, or we could think about ham radio projects. I think I will choose the rig projects.
Several weeks ago, I started work on a CW Transceiver. But my approach was to not just use a warmed-over project of old (another Bitx topology) but to use PNP transistors. Hey, guess what they do work!
So what is so special about using PNP devices other than:
1) They are not often seen in RF Circuits
2) They have some very good specs such as power dissipation and cutoff frequency
3) They can be integrated with NPN Devices
4) They can be readily found often at great prices
5) They offer an opportunity to explore the use of a new circuit topology. (Grounded Collector)
6) They make you the odd duck for even trying to use them (The best reason).
I think much of the lack of use of PNP transistors is the circular firing squad syndrome. Hams are great at copying others work. I am greatly amused by how many new SSB transceivers projects are a Bitx topology in disguise yet described as new. Simply stated there are not many projects with PNP devices and so nothing to borrow from which results in no "new projects".
So here is your chance -- get a bag of 2N2907's and another bag of 2N2905's and you are on your way. Avoid suppliers like AliExpress or Banggood (you got to be joking picking a name like that). Often products from these suppliers are duds!
Simple circuits are the best place to start. Something I did discover is that the Russian Germanium PNP RF Transistors which used to be cheap work very well at HF. But no more of the 100 transistors for $20. Parts from the Ukraine are particularly excellent.
Time to get back to the workbench and build something.
TYGNYBNT
73's
Pete N6QW