10-09-2006, 08:57 AM
The 660 and 665 are very similar electronically to the 1936 Model 116B chassis; they even used the same chassis pan.
They differ in frequency coverage and, of course, the 116 uses eleven tubes while the 660/665 uses ten. The 660/665 uses a single tube, a Type 75, as 2nd detector-1st audio; this job is handled by two separate tubes in the 116 - Type 37 as diode-connected 2nd detector, Type 77 as 1st audio. The 116 uses a five-point tone control; the 660/665 has a four-point tone control.
The 660/665 has a large, round metal hole cover over a hole cut for a Type 77 tube socket which was used in the 116B. The 660/665 wave trap adjustment is underneath this hole cover.
They differ in frequency coverage and, of course, the 116 uses eleven tubes while the 660/665 uses ten. The 660/665 uses a single tube, a Type 75, as 2nd detector-1st audio; this job is handled by two separate tubes in the 116 - Type 37 as diode-connected 2nd detector, Type 77 as 1st audio. The 116 uses a five-point tone control; the 660/665 has a four-point tone control.
The 660/665 has a large, round metal hole cover over a hole cut for a Type 77 tube socket which was used in the 116B. The 660/665 wave trap adjustment is underneath this hole cover.
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Ron Ramirez
Ferdinand IN
