My Vintage Computer Virtual Museum and blog page.

Carterfone Data Coupler 337 Modem

My Carterfone Data Coupler 337 acoustic coupler modem (added to my collection in 2018)

Date stamps on the components inside date this modem to somewhere in mid 1969.

This page will be updated as I learn more about this modem, and get it repaired and working correctly.  As of now it powers up and briefly produces a tone, however it will not recognize a carrier tone and respond, and it appears to be originate mode only, so I can’t have it attempt to answer a data call either.

I haven’t spent too much time on this yet, but I did get an oscilloscope on the power rail (24VDC) and there was a lot of AC ripple, so I have replaced the main axial filter capacitor on the power supply, that’s cleaned up the AC ripple, but has not changed the behavior of the modem.  I will have to figure out values and start replacing other capacitors, it’s mostly axial caps, which I don’t have any on hand, so I am having to special order all the caps for this project.