#16
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Ok so it's all recapped now and it works but the volume has to be maxed to here anything the audio is super very low, but I am unable to test the tubes so I'm assuming the 84 is good as well as the 6a7 being its pulling in a station which is local here to me. So is it possible one of the other tubes may be bad like the IF, 78 or the 75 2nd Det 1st audio tube, or even the 41 output tube ? Maybe rule out anything else.
Last edited by timmy; 06-12-2018 at 11:37 AM. |
#17
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I don't know what the proper ohms should be on the Transformer on the speaker but I measured the primary input .730k ohms and the secondary to the speaker,2.0 ohms and the speaker coil itself, 4.5 ohms. I originally plugged it in and got the typical loud buzz and hum out of the speaker so if anything the speaker and coil should be good. The field coil that's on the speaker itself measures 1.758k
Last edited by timmy; 06-12-2018 at 12:11 PM. |
#18
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Those are all DC resistances on the output transformer, speaker and field coil and they look alright. Also the negative on the input electrolytic should go to the bias line instead the chassis. Also check the bias resistors, 400 and 75 ohm. |
#19
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primary does show its 450ohms I'm getting .730k. There is a 70 ohm resistor and it's ok but I don't see a 400 ohm resistor. the 190k I replaced with an array at 186k and the 490k I replaced with 470k . |
#20
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How long of an antenna wire are you using? jr |
Audiokarma |
#21
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Well the schematic shows 190,000 so that should be 190k . Wire for the ant is like 3feet long.
Last edited by timmy; 06-12-2018 at 04:19 PM. |
#22
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10'+ is better. 100'+ is ideal.
__________________
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 |
#23
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I'm pulling my hair out , this simple radio should work, well unless a tube is bad then I would have to get 4 of them since the voltages look good so then rectifier tube is good.
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#24
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It doesn't look like you have many strong AM choices.
https://radio-locator.com/cgi-bin/lo...req=&sort=freq Have you tried peaking the if transformers? Longer antenna wire? Is the dial calibration fairly close, or does the set need alignment? jr |
#25
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Audiokarma |
#26
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You may be able to rule out audio by injecting audio past the detector and seeing if volume is adequate.
__________________
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 |
#27
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#28
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That Philco radio is just as hot as any other AA5 with similar circuitry. It's a standard AVC equipped radio, not one of those non-AVC circuits, where the volume control is located in the antenna and bias circuit. Make sure the bias voltages are on the money as they affect the first and second audio stages. |
#29
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jr |
#30
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Ok I have a cheap am radio and it works fine and loud strong signal, since the station is near me. The 75 tube cap off there is a buzz touching the cap and not all that loud and cap on less buzz touching it. The 6a7 wet my finger and touch the cap and the station comes in Alittle stronger. I will check the voltages on the 78 and 75 tubes again.
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Audiokarma |
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