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: : : : : : : : : : : :Sir Brian Ceeeeeeee. . . . . : : : :Your . . . . : : : :From the little I know about it, the light is suppose to either dim, or, come on stronger as a station is tuned. : : :There is a schematic here on this site that shows the tuning light, and I can't figure how it works in the circuit. : : : :Since you HAD mentioned that the lamp socket is a screw type I was going to suggest the use oof a 48 lamp which is 5 V rated and only needs 60 ma, but IF your grain of wheat lamp is their 6 v rated unit and NOT the 12 V rated unit, you should fly with what you have. : : :As per the functionality of the tuning circuit . . . consult my provided mark up of your unit beeeeeeeeelow: : : :Hang on reeeeeeel tighte . . . heeeeere we go . . . . . : : :The B+ of our interest starts at my [BLACK-A] as the orange buss and flows up to the tandem arranged Tuning Lamp and its shunted voltage buffer shunt resistor R10. : : :They then feed that B+ through to the [BLACK-B] and that in turn flows up thru the IF transformer primary to the Plate of the 6K7. : : :The [BLACK-B] additionally feeds over to the left and up through the 1st IF transformer primary and into the Plate of the 6K7 mixer. : : :The quiescently biased values of the 1st grids on those two tubes will determine the current consumed by the plates. : : :That level will be ascertaining the intensity of your tuning lamp, which will not be anything phenomenal, like it would be if you were doing the same thing on the more current intensive output AF amp . . .BUT that fluctuates with audio changes. : : :The other aspect of the tuning action is the AVC circuitry, which i have markeds up as GREEN busses. : : :Its derivation is from the low bottom end of the secondary of the 2nd IF transformer and with you seeing it initially as [BLACK-1] and then passing thru a hi freq C-R-C pi- filter network, to route to the right to feed its audio to the volume control. : : :Its Negative DC element is your AVC control voltage and travels to the left untiul its encounter at [BLACK-2] with its first voltage dropping/ impedance shifting resistor, as that R7, so be sure that it is ~500K and hasn't done a time related walk up in value. : : :Then . . . .AND THEN . . . I believe there is what your problem will probably be . . . in the form of that series arranged BC-1 . . . . or as I call them "Bone " Cells . . . 'cause after fifty and 'lebenteen somewhat years, they are dry as bones and open circuited. : : :That AVC circuit is dependent upon the AVC flowing THROUGH that cell and additionally acquiring its paltry little volt or so . . . (at no extra charge ! ) . . . to then to complete the AVC loop flow path on down to [BLACK-1] :The AVC then flows up to the 1st grid circuitry of the 6K7 at [BLACK-4] and also over to the left and upwards to the first-us grid-amus of the 6A7 mixers circuitry at [BLACK-5] . : : :That constitutes the sets AVC flow action and with a strong good signal, the negative voltage application should cause the quiescent state plate currents to progressively decrease and be shown with your tuning lamp dimming. : : :The degree of dimming , of course is not going to swing the gamut of a full brite to half brite, as the plate current swing of those two tubes is being nowhere near 30 ma. . . . lucky to even see that on the AF output tube at full blast. : : :Now get your AVC a wukkin' and sees what gives . . .AND BTW there is companion Bone Cell-2 over there associated with the 1st AF amp stage, and should also require attention. : : :Be sure that the C 21 coupling capacitor on the volume control has ZERO DC leakage, also, the same goes for bypassing cap C21 on the AVC buss . : : : :WWED? . . . as per What Would Edd Do ? : : :Methinks that if this was my set to do, this would be an excellent application for a WHITE . . .or your desired color . .(excluding Mauve and polka Dotted !) . . . . high intensity LED being used instead of that incandescant lamp. : : :You merely install with the + of the LED being towards the B+ buss anmd the - going towards the tubes plates. : : :The combination of the R10 + paralleled Tuning Lamp and series R9 are responsible for the reduced supply B+ level to the Osc and frontal RF tubed screen grids supplies. : : :With R9 being responsible for ~4/5 th of that voltage dropping function, therefore by dropping the value of R10 to limit the max brightness of the LED would be permissible. : : :Toy with its value to end up with the most desirable brightness swing between an off station and tuned to strongest station avauilable testing. : : :Lowering the selected R10 resistor value , limits the max brite. : : : 73's de Edd : : : : :Forever is a long time, but its not quite as long as it was yesterday. : : : : : : :

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: : : The Rogers Majestic 11-60 Marked-Up Reference Schematic: : : : : : : : :

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::Has anyone tried a 1448 ? I don't have any - there are a few places it can be ordered - it seems to fit the bill.
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::http://www.bulbtown.com/SearchResults.asp?Search=1448
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::In the past I've taken some small bulbs that I have here that were rated 28 volt at 40 mA - but it was a pain in the butt to retrofit them into a miniature screw base - they worked - but I would have liked them to have been just a little brighter.
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