Help please to identify this mystery object

[MisterHeadache]

I've had this guy in my junk box for years, it came with a grab bag of stuff.  On the outside it sure looks like a crystal or mechanical filter, but I cannot find any info about it online.  Filtronix is now a different kind of filter company, and searching for 'Filtronix 487-006' yields the extremely rare zero hits in Google.

Full text on it reads:

Filtronix
Type 487-006
5.5-2.7  72-29

If it turns out to be a really good bandpass filter, I may use it in a future project.  If not, then it's going in the rubbish bin.  Or I might take a stab at it with my signal generator and SA to see what it does.

Any thoughts what this is?

[Grandchuck]

Crystal filter with 2.7 kHz bandwidth centered at 5.5 MHz.  Just a wild ass guess!  If so, makes for a SSB application.

[Mechatrommer]

probably similar to the one used in SWAN-350C SSB Transceiver (SSB or C-F filter?) i dont know what is it but i have a feeling that Grandchuck is not telling us everything
https://www.mhrep.com/product/swan-350c-original-c-f-filter-model-5-5-2-7-used/
https://www.roetta.it/ik3hia/pages/Hamradio/swan350c.htm

googling more "ssb filter 5.5-2.7" reveals more relatives of look alike...
CW /SSB 2.7K narrowband filter compatible with YF-122S module For YAESU FT-817/818/857/897 MURATA CFJ455K13
at least you can sell it at $50-80 ... maybe filtronics or filtronetics have some relation? ymmv.

[WattsThat]

That’s a Heathkit format part number, date code sure fits. Don’t have my master list to look it up, you might be able to find a list on the web.

[MisterHeadache]

Mystery solved. I had a window of opportunity this week to put it on a network analyzer (see below picture), and if the printing were interpreted to mean its application was for a USB filter for a 5.5MHz carrier, then that makes sense.  A 2.7kHz bandwidth is believable based on this data.  It has good symmetry in both tails, so conceivably it could be used for LSB if the carrier were shifted up accordingly.  There’s ripple in the passband, but I just did a quick solder connection to RG316 coax and it also may have a higher impedance than the 50 ohms of the NA.  Not sure what max power it can handle, though - I tested it at 0dBm.

I had no luck digging deeper for a Heathkit part number, though.

Thanks Grandchuck for the tip, you put me on the right track.  Now I might just be able to use this little guy for a future homebrew SSB transmitter project…