Total posts : 45366
Thanks for the hints & info. When I got into this design thing on the amp/switch/LPF &c board design, I ended up with bypass caps on the board that weren’t on my reference schemo. I went nuts with the little puppies and parked .01s and .001s all over the board on various DC lines. That and a handful of 10 & 100 uF tantalums. So I figured I was pretty good there. Also I used the ferrite bead chokes that were part of the QKits.com boards. (The kits are really from KitsRus, based on many of SM0VPO’s designs.)
Putting each section in its own little tin strip box also saved me many interaction episodes (usually resulting in me having to replace the window screen near this desk). I did not, however, put a bead on the base lead to the 2N3866 clone that comes with the Qkits board.
Last night, after I’d gibbered here, I pulled out the tuning tools & tuned the BPF to the frequency I was parked on (107.3 MHz). That was a big help in giving the signal a “no so smothered” tener, which was the game plan at that time.
I’ve also built into the box, using RG174 (yeah, I know, Ethernet hose is best), a 2*f stub filter. Putting that in dropped my apparent output in half, which is either a curse or blessing, depending on whether or not I blammo the neighbor’s VHF fire/rescue HT. (He’s one of the local fire fighters & I don’t wanna get in their way, even if only from my back yard out to the street.)
So backing up & doing a retune helped greatly. So much for the “no tune” style of radio that I’ve gotten used to since I worked on the TR7 line at Drake something like 25 years back. Hard to believe that my TR7 is that old. But then the morning paper informed me that, as I hit the 60 mark, I’m joining a list of survivors.
Sweet. Now can I stay up late to watch reruns of “Miami Vice”?