48-1270 alignment - Printable Version
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+--- Thread: 48-1270 alignment (/showthread.php?tid=22604)
48-1270 alignment - Bigreddog42 - 07-05-2021
I've recently recapped a 48-1270. Its working pretty well but I want to fine tune it to improve reception - I'm a little distant from good stations. The Philco service manual has pretty good instructions for alignment of the 48-1270, but I need a little more elaboration on the first alignment step for AM. The manual instructions for attaching the signal generator for step one reads as follows "Through a .1-mf condenser to aerial section of tuning gang." I am familiar with the stator section of the tuning gang, but I am having difficulty determining which part is the aerial section. I've tried to determine through schematic but can't be sure. So, I've tried this: There are two lugs on top of the condenser - one over each tuning section. When I touch the lug farthest from tuning cord with my finger the signal for a strong AM station gets considerably stronger. When I touch the lug closest to the tuning cord the signal disappears. Does this help discriminate between aerial and oscillator sections. I am guessing the first lug (farthest from tuning cord) is the aerial section. I sure would appreciate some help on this - don't want to mess this up really bad. Thanks.
RE: 48-1270 alignment - morzh - 07-05-2021
On the sch there are 3 sections shown. Top to bottom, the middle one (next to R411) I think is the Aerial.
RE: 48-1270 alignment - Bigreddog42 - 07-06-2021
Thanks morzh for redirecting my attention to the schematic. I was having a little trouble mapping the schematic to the physical tuning condenser. However, I noticed in schematic that WS2(F) pin 7 connects the aerial to the condenser. So, I "followed" that wire with a continuity check to the proper lug. I think I am good to go.
RE: 48-1270 alignment - Bigreddog42 - 07-06-2021
AM alignment went well. Set performs pretty well with built-in loop antenna. Will work on FM alignment later.