I received a project D1 in the mail this afternoon. I'm doing some exploring, wondering what this little guy is? (Circled in blue) I've never seen it before.
A dial pulse spark surpressor
Hmmmmm interesting.
That was referred to as a filter. I'm not sure but I think it was something to do with the service for the customer.
I always thought it was a radio frequency filter to block out radio stations broadcasting on your phone
Asked and answered many times on the forum.
Use the search function for "61A filter" for about 12 links to a discussion of this filter
(http://www.classicrotaryphones.com/forum/index.php?action=dlattach;topic=18803.0;attach=167718;image)
(http://www.classicrotaryphones.com/forum/index.php?action=dlattach;topic=6192.0;attach=88728;image)
Several informative, technical posts about the filter were posted, most by unbeldi:
http://www.classicrotaryphones.com/forum/index.php?topic=18803.msg193517#msg193517
http://www.classicrotaryphones.com/forum/index.php?topic=11422.msg171272#msg171272
http://www.classicrotaryphones.com/forum/index.php?topic=17062.msg175977#msg175977
http://www.classicrotaryphones.com/forum/index.php?topic=6192.msg73260#msg73260
The RFI surpressor is the small capacator across the transmitter capsules on E1 and F1 handsets . This is so radio signals are not detected and heard in the receiver. The filter on the dial prevents sparks that can cause interference to radio sets (popping)