jan 18 ? attempting to edit??? original which mostly went into "quoted text"
i have got this topic still dangling in my drafts-unresolved basket ..and am trying to get closer to an answer.
On Fri, Nov 4, 2022 at 02:12 PM, Richard Knoppow wrote:
- I still am not clear on a couple of things.? Is the double peak on one station only?? And secondly how are you seeing it?? I thought the 62 does not have a tuning indicator, am I wrong?? ?A problem with the IF or detector should show up on all stations.? If this appears on one station it is something else
Richard; I believe he does not need to see it with a tuning meter; as one tunes, the station audibly becomes fairly clear then becomes weak and/or distorted, then becomes clear again.. that's from my memory of some stations back in the late 1950's
I bypass the other fragments for now.
Re: an earlier comment...Re:" the rotor is going past maximum"...
- I am not familiar with the construction of the SX-62 but wonder if it's possible that the rotor is going past maximum capacitance so that it's tuning higher again.? Visual inspection would probably tell.
Richard; you really pulled the wool over my eyes, and i guess the others too..I've been conned!, cant think!!!
It seems to me the frequency of 88.7? is close to the bottom of the official new FM band [ center frequency = 87.9?MHz ], as we knew it? after 1945, but we hardly need to inspect the tuning cap; just look at the SX-62's specs or better, just look at the dial scale. i clearly see it starting before 54 Mcees and ending just over 108 Mcees ----so 88.7 will be near mid range of the sx-62 scale, so the tuning cap must be near mid rotation; nowhere near the end of "normal-nice-curve" of capacitance vs degrees of rotation.
also; you likely meant "below minimum", not "past maximum" , which could also apply.?
Now, I somewhat? agree, with some suggestions that the problem might be in the IF, and due to bad alignment, or some IF cap [not SMD] shifted, but we expect double tuning all over the FM band, and we never had any input from Waldo? on that..
I am going out on a limb to suggest an alternative: especially if the signal is weak, the limiter action are is poor, and normal Fm detection fails, but the wide side slopes of the old IF circuits, will allow [AM] slope detection when tuned to either above or below the center frequency. Likely, poor tuning of the IF will make this more likely..
73 don VA3DRL?
don Root