What's this doohickey? It's a 61A interference filter

[Devansphones]

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.

[rdelius]

A dial pulse spark surpressor

[Devansphones]

Hmmmmm interesting.

[Key2871]

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.

[Doug Rose]

I always thought it was a radio frequency filter to block out radio stations broadcasting on your phone

[Global Moderators]

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






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

[rdelius]

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)