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looking for ceiling fan run caps but wow stores dont seem to sell them locally. Thought for sure Id drum one up quickly.
Fixed miswire of the 2Meg ohm and the 1 Meg ohm resistors off the 77 and 38 tube. Im hoping these arent 2000 and 1000 ohm and Im reading it wrong again as some of these sets meg meant K. Coming off the 77 tube screen is a 2 MEG and that goes to the screen of the 38 tube. I had the 2 MEG resistor going from plate to screen of the 77 tube. The 1 MEG resistor was also miswired. Now 1 MEG goes from screen of 77 to screen of 38 . The C bias for the 38 tube is 10.8 volts, not sure if .8 is close enough to the required 10 volts specified bias for 38 tube. Still very low output although slightly better after resistor miswire. j Also going to guess the .05 cap across the line isnt responsible for the extreme loss in volume. Last edited by fumplet; 05-08-2023 at 04:09 PM. |
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Is there any real strong stations in your area? 20 to 50 KW? With the 38 output tube, it's only rated at .55 watts. Those sets really were never too loud! |
#3
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As far as loudness I only get volume the last 1/16 or slightly more of the volume knobs rotation basically 98 percent of the volume control from max. Seems somewhat odd unless I really do need the much longer wire for the antenna. Getting tired of trying to find the exact capacitor to make the tubes get 6.3 volts each. contemplating the 1n4007 diode approach. but if I were to use a diode IM not sure how much affect a capacitor would then have to drop voltage Last edited by fumplet; 05-14-2023 at 07:36 AM. |
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Ok added some more antenna wire and it didnt do much UNTIL I retweaked the trimmer caps on the tuner and that woke it up. So now it still sounds like it needs more cap filters and the dreaded speaker rattle.
Ripped off what was left of the outter speaker gasket and cut out a new one from poster board. Not quite thick enough so I will double up another gasket. speaker rattle seems gone. This set must have been really wet or dropped in a bathtub yet still works. Last edited by fumplet; 05-14-2023 at 02:33 PM. |
Audiokarma |
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__________________
Tom C. Zenith: The quality stays in EVEN after the name falls off! What I want. --> http://www.videokarma.org/showpost.p...62&postcount=4 |
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BTW, is there a 300 ohm resistor in series with the high end of the volume control? It might be part of the control! |
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still working on correct capacitor for line and tube voltages. Right now 7.3uf gets me 6.2 volts on tube filaments. Should I be worried about .1 of a volt Im not sure. Cannot use the fancy formula in another thread as it is supposed to use microsoft excel which requires me to go purchase microsoft 365. Swapping and combining caps is more fun anyway.
Just looked at meter and its now showing 6.24 volts. It seems to vary just like the line voltage so Im betting thats close enough. Next is to hunt for the 300 ohm volume resistor unless its in the volume pot itself. I have yet to figure out why bumping the tuner gets radio to play like tuner fins are losing connection to the fixed part of the tuner. Experience is telling me connection or coil bad somewhere. |
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bought ceiling fan caps that have 4.5 5 and 6uf with a common gray wire. I figured I could parallel the cap itself with the values it has to get various values but if I use more than one colored wire, the radio tubes light at a much lower line voltage. Seems to only work if I parallel 2 separate physical caps together. CBB 61 is the ceiling fan cap number. NOt sure why they have 2 gray wires on these caps if they are tied to the same common end internally.
I series strung the 2 cbb 61 caps at 16uf to make 8 uf and tube voltage is 7.02 volts. Going to guess a 7 or 7.5 cap will do it. Last edited by fumplet; 05-13-2023 at 07:39 PM. |
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