where can I get a 145MHz helical filter these days?

[bd139]

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.

[eliocor]

Maybe this can help:
https://www.rf-microwave.com/en/tunable-helical-band-pass-filters/418/

[phenol]

Temwell-Taiwan. They have toko replacement parts and their own models.

[bd139]

Maybe this can help:
https://www.rf-microwave.com/en/tunable-helical-band-pass-filters/418/

Ahha perfect! Reasonable prices too. Thank you for this. They do ones which bottom end is 144 which is a bit tight but I can push the 1st IF to 170 which will do the job. Will change 2nd LO to 160 (multiplied up from 20Mhz) and then use cheap crystals for the 2nd IF filters.

[GerryBags]

I found a couple of domestic options, I think:

https://www.ebid.net/uk/for-sale/telonic-tubular-tba-140-17-4ab1-140mhz-centre-freq-rf-bandpass-filter-bncs-150054037.htm
"TBA 140-17-4AB1 140MHz centre freq 131.5-148.5 MHz 3dB Bandpass 4 section 50 Ohm
BNC male to female"

I'm not sure if you're familiar with www.radwell.co.uk but they can be useful for parts, particularly obsolete stuff. You really need to enter p/n's to find much, though. I managed to get a replacement tek P6137 probe tip from them, had no luck finding any others in the UK.

[Karlo_Moharic]

This guy made one, and it doesn't seem like a hard project, so 

[bd139]

I can’t be bothered with that 

I found a couple of domestic options, I think:

https://www.ebid.net/uk/for-sale/telonic-tubular-tba-140-17-4ab1-140mhz-centre-freq-rf-bandpass-filter-bncs-150054037.htm
"TBA 140-17-4AB1 140MHz centre freq 131.5-148.5 MHz 3dB Bandpass 4 section 50 Ohm
BNC male to female"

I'm not sure if you're familiar with www.radwell.co.uk but they can be useful for parts, particularly obsolete stuff. You really need to enter p/n's to find much, though. I managed to get a replacement tek P6137 probe tip from them, had no luck finding any others in the UK.

Thanks for the link. Appreciated. Will find some specs. That might do the job.