Attempting desperately to revive a project I've been working on for a few years, which is a simple 100MHz SA for use on HF. Nothing exciting - just enough to see 2nd/3rd harmonics, IMD, carrier suppression etc. The 1st IF is 145MHz. I was planning on grabbing a canned Toko 145MHz helical filter for this but as usual, they completely disappeared off the market immediately when I worked on that part of it. I spent today respinning the log amp and video filter from an NE604 RSSI (which I blew up) to an AD8307 based on a power meter design I already threw together. This is working nicely.
Options are to build my own helical filter or buy one. Preferably the latter. Does anyone know any sources for these? If not, any design information on how to build one worst case. I don't have a swept generator other than the first mixer on this thing, an NE602 so aligning it is going to be a dick if I build one. Was hoping to avoid that
Hopefully if I can solve this I can throw a 2nd IF together (12MHz) and actually finish the damn thing.