12-17-2018, 10:56 PM
From what other members mentioned a slight variation doesn't matter but I have reached the Cathode By-Pass for two tubes.
The value of .09uf is required or listed in the schematic and all I have is .082uf and .1uf both at 630 volts. Are both acceptable the .1 being lets say .0999 plus or minus or am I wringing my hands over such small amounts especially in the "front end" of the receiver? These are located in the Bakelite Block capacitors and are not the easiest to replace if one is too big and one is too small OR is bigger better or small better? It's this with my yellow Polypropylene or dig through a large box of bulk Disk Ceramics perhaps needlessly?
Some more info on these cathode bypass capacitors is each on is used for: 6A7 a heptode operating as frequency changer with electron coupling, and 78E listed as a variable-mu H.F. pentode operates as I.F. amplifier
Also a bit off topic but on the other hand tolerance comes to play again and this is with the wiring to these same two tubes. the 6A7 and 78E both use a guesstimation of 16 gauge wire to the cap on top while the PenDD61 uses approx. half the gauge and the wire is a feeble cotton covered thread compared to the other two. Why is there such a difference in wire gauge which is also making me paranoid on the capacitor values? The PenDD61 was that multipurpose Valve or Toob that is both detector and audio output. This tube (PenDD61) with the very light cap wire is described as Diode second detector is part of double diode output pentode and Audio-frequency component in rectified output, so the story goes from the 1936 Trader Service Sheets
According to the schematic this set is equiv. to the Philco 269 with slight mods to the 444.
Yes I have a number of radios in my collection that have been sitting for years with original capacitors not replaced and as I replace these in the 444 during replacement ALL have failed tests on my Heathkit IT-11 capacitor tester miserably to the point of probably causing severe damage if I would have plugged in this radio first.
The value of .09uf is required or listed in the schematic and all I have is .082uf and .1uf both at 630 volts. Are both acceptable the .1 being lets say .0999 plus or minus or am I wringing my hands over such small amounts especially in the "front end" of the receiver? These are located in the Bakelite Block capacitors and are not the easiest to replace if one is too big and one is too small OR is bigger better or small better? It's this with my yellow Polypropylene or dig through a large box of bulk Disk Ceramics perhaps needlessly?
Some more info on these cathode bypass capacitors is each on is used for: 6A7 a heptode operating as frequency changer with electron coupling, and 78E listed as a variable-mu H.F. pentode operates as I.F. amplifier
Also a bit off topic but on the other hand tolerance comes to play again and this is with the wiring to these same two tubes. the 6A7 and 78E both use a guesstimation of 16 gauge wire to the cap on top while the PenDD61 uses approx. half the gauge and the wire is a feeble cotton covered thread compared to the other two. Why is there such a difference in wire gauge which is also making me paranoid on the capacitor values? The PenDD61 was that multipurpose Valve or Toob that is both detector and audio output. This tube (PenDD61) with the very light cap wire is described as Diode second detector is part of double diode output pentode and Audio-frequency component in rectified output, so the story goes from the 1936 Trader Service Sheets
According to the schematic this set is equiv. to the Philco 269 with slight mods to the 444.
Yes I have a number of radios in my collection that have been sitting for years with original capacitors not replaced and as I replace these in the 444 during replacement ALL have failed tests on my Heathkit IT-11 capacitor tester miserably to the point of probably causing severe damage if I would have plugged in this radio first.
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