Hi Bill,
you do not have to stick to the Polish supplier when you have a similar one.
link here: https://www.ebay.ie/itm/5PCS-433-92-MHz-SMD-433MHZ-433-433-92-RF-SAW-Filter-Surface-Mount-QCC8C-SM3838-8/273962954133?hash=item3fc976ed95:g:DUkAAOSwudBdT4~K
I looked at the technical features as the B3555. Compare.
NDF550 link: http://13.124.15.139/pdf/download.php?id=3a61bc5ecdd2a26caa4d25a4aeb11c8e88e357&type=P&term=ndf55073
ps.: eBay item number:? 273962954133
?
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Gyula HA3HZ
Gyula Molnar