The Fine Things are Always Hand Made
Small puzzler this evening...I am aligning a Scott Masterpiece that I just overhauled. The set plays well, and all the tuning adjustments went "by the book" except for one: the 1st IF, under the chassis (I <think> that is the secondary): no matter what I did with the adjustment, it made no change to the IF alignment. The set does play nicely, and all voltages are in spec. I don't hear a broken slug rolling around in there. Any ideas before I decide to take it apart to find out why it doesn't "trim"? Or should I just leave it alone since it plays very well?
Are you injecting the signal to the grid of the converter? If injecting to the grid of the first IF, the IF primary adjustment will be irrelevant and impossible. If it is in fact the secondary of the first IF transformer that will not peak, check the narrow-broad selectivity switch for good continuity in both the narrow and wide band positions and the 100pf capacitor for shorts.
I am injecting the 455 signal on the converter, and my IF alignments usually go well on all six adjustments. The narrow/wide selectivity seems to work ok, but I will check the capacitor, I hadn't thought about it being shorted. I'll let you know what I find. Thanks!
OK, went in and opened the IF can up. The capacitor is fine, also, I've determined that the lower (under chassis) adjustment is for the primary (converter plate) side of the transformer. Still no action, but...
I have decided to just use the set as is though...it's a very cold, fairly clear night here in Ohio, and as I "worked" the AM band, I got the following: WFAN (660, NYC), WOR (710, NYC), WGN (720, Chicago), WBBM (780, Boston), WBZ (1030, NYC) and WHO (1040, DesMoines IA). All in about 10 minutes. Also grabbed a "pirate" SW station on 7.490 Mz called VORW. Faded in and out a bit but he played good music. It sounds nice, so I think I'll leave it as is...