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:Above comment assumes that the tubes have been tested and exonerated. Tubes are always the most likely suspects.
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: :OK, finally was able to make some checks. I learned that the IF transformer is OK. The cathode resistor is OK. Voltage on the 6sk7 plate is 89 and same on the screen grid. I noticed that the grid is measuring -0. I punched all the buttons several times and cleaned the one for the tuner. I do hear unmodulated whistle-like sounds where I believe stations would be. Still stuck. Any more thoughts are appreciated. : :  : : : : :Sir Mike. . . . . : : : : : :Some additional possibilities: : : :While ohmming out the IF transformers also check out the cathode resistor and then move on to a powering up of the set : and confirm ~65-85VDC on the plate and screen of the IF amp. : : :Now, is all of the AF sectino OK ? : : :Quick check . . . other than the wetted finger to the 1st grid of the 'Q7 is using two jumper wires with their clip ends : : :and connect a ~.01---.1 ufd cap between pin 7 and 4 of the 'Q7 and gradually run the volume up and be expecting a : : :progressively louder "HUMMMMMMMMM" up to a threshold of the thorough cleaning of cob webs from the speaker. : : :That confirmation is a clean bill of health of all of the AF system from the detctor diodes thru to the speaker. : : : :If the IF- RF- Mixer stages had their Bee Pluss-es-es Voltages-es-es being present . . . . then try this. : : :Give the push buttons M-U-L-T-I-P-L-E workout punches . . . to clean any oxides off its switches and finally leave : : :in the manual tuning position. : : :Confirm that your external loop is present and plugged in. : : :Take one of the . . . now semi retired . . . previous test leads w/ end clips and leave it clipped onto that pin 4 det : : :plate of the 'Q7 and take its other end and clip to a short length of insulated hook up wire . : : :That wire end is being bared of insulation, just enough to clip onto and make connection. : : :The balance of the insulated wire is to be multiple turn wound around the 1st IF transformers BLUE lead wire that routes to the 'SA7 mixer toobie. : : :(You are accomplishing low picofarads of coupling capacitance with that "gimmick" construction.) : : :SHOULD you be so fortunate as to actually have a 10-20 or so pf capacitor in stock, use that for direct interconnect. : : :(I 'm usually catering to a possibility that the requestor of info . . . quasi servicee . . hasn't a pot to pee in . . .figuratively : . . . as per parts availability on hand . . . . or more importantly . .any test equipment. ) : : :Next, use the other unused "jomping -jimminy ! " clip set to short across the primary of the 2nd IF transformer . . . .we :certainly dont wants no interstage "ossifrying"/feed back ocurring there ! : : :NOW . . . .AND NOW . . . . fire up your 'ole At-water-less Kent . .(WANNABE !) . . . and just see if some of your stronger : : :stations are coming in as you cruise across the dial scale tuning on that ole' Rota-mola ! : : : : :Standing by . . . . . . : : : : : : : : : : : : : : : : :73's de Edd : : :  : : : : : : : : : :The first 90 percent of an involved task takes 90 percent of the time, with the last troublesome 10 percent taking the other 90 percent. : : : : : : |
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::Above comment assumes that the tubes have been tested and exonerated. Tubes are always the most likely suspects.
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:: ::OK, finally was able to make some checks. I learned that the IF transformer is OK. The cathode resistor is OK. Voltage on the 6sk7 plate is 89 and same on the screen grid. I noticed that the grid is measuring -0. I punched all the buttons several times and cleaned the one for the tuner. I do hear unmodulated whistle-like sounds where I believe stations would be. Still stuck. Any more thoughts are appreciated. ::Also: now see that the plate voltage on the 6sq7 seems out of whack. It measures about -50 volts measured against B-. :: :: :: :: :: ::Sir Mike. . . . . :: :: :: :: :: ::Some additional possibilities: :: :: ::While ohmming out the IF transformers also check out the cathode resistor and then move on to a powering up of the set :: and confirm ~65-85VDC on the plate and screen of the IF amp. :: :: ::Now, is all of the AF sectino OK ? :: :: ::Quick check . . . other than the wetted finger to the 1st grid of the 'Q7 is using two jumper wires with their clip ends :: :: ::and connect a ~.01---.1 ufd cap between pin 7 and 4 of the 'Q7 and gradually run the volume up and be expecting a :: :: ::progressively louder "HUMMMMMMMMM" up to a threshold of the thorough cleaning of cob webs from the speaker. :: :: ::That confirmation is a clean bill of health of all of the AF system from the detctor diodes thru to the speaker. :: :: :: ::If the IF- RF- Mixer stages had their Bee Pluss-es-es Voltages-es-es being present . . . . then try this. :: :: ::Give the push buttons M-U-L-T-I-P-L-E workout punches . . . to clean any oxides off its switches and finally leave :: :: ::in the manual tuning position. :: :: ::Confirm that your external loop is present and plugged in. :: :: ::Take one of the . . . now semi retired . . . previous test leads w/ end clips and leave it clipped onto that pin 4 det :: :: ::plate of the 'Q7 and take its other end and clip to a short length of insulated hook up wire . :: :: ::That wire end is being bared of insulation, just enough to clip onto and make connection. :: :: ::The balance of the insulated wire is to be multiple turn wound around the 1st IF transformers BLUE lead wire that routes to the 'SA7 mixer toobie. :: :: ::(You are accomplishing low picofarads of coupling capacitance with that "gimmick" construction.) :: :: ::SHOULD you be so fortunate as to actually have a 10-20 or so pf capacitor in stock, use that for direct interconnect. :: :: ::(I 'm usually catering to a possibility that the requestor of info . . . quasi servicee . . hasn't a pot to pee in . . .figuratively :: . . . as per parts availability on hand . . . . or more importantly . .any test equipment. ) :: :: ::Next, use the other unused "jomping -jimminy ! " clip set to short across the primary of the 2nd IF transformer . . . .we ::certainly dont wants no interstage "ossifrying"/feed back ocurring there ! :: :: ::NOW . . . .AND NOW . . . . fire up your 'ole At-water-less Kent . .(WANNABE !) . . . and just see if some of your stronger :: :: ::stations are coming in as you cruise across the dial scale tuning on that ole' Rota-mola ! :: :: :: :: ::Standing by . . . . . . :: :: :: :: :: :: :: :: :: :: :: :: :: :: :: :: ::73's de Edd :: :: :: :: :: :: :: :: :: :: :: :: ::The first 90 percent of an involved task takes 90 percent of the time, with the last troublesome 10 percent taking the other 90 percent. :: :: :: :: :: :: |
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:::Above comment assumes that the tubes have been tested and exonerated. Tubes are always the most likely suspects.
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: : :I hear faint and garbled stations when I make this coupling, Edd. What sort of problem does this suggest? : : : : : :Sir Mike. . . . . : : : : : :Some additional possibilities: : : :While ohmming out the IF transformers also check out the cathode resistor and then move on to a powering up of the set : and confirm ~65-85VDC on the plate and screen of the IF amp. : : :Now, is all of the AF sectino OK ? : : :Quick check . . . other than the wetted finger to the 1st grid of the 'Q7 is using two jumper wires with their clip ends : : :and connect a ~.01---.1 ufd cap between pin 7 and 4 of the 'Q7 and gradually run the volume up and be expecting a : : :progressively louder "HUMMMMMMMMM" up to a threshold of the thorough cleaning of cob webs from the speaker. : : :That confirmation is a clean bill of health of all of the AF system from the detctor diodes thru to the speaker. : : : :If the IF- RF- Mixer stages had their Bee Pluss-es-es Voltages-es-es being present . . . . then try this. : : :Give the push buttons M-U-L-T-I-P-L-E workout punches . . . to clean any oxides off its switches and finally leave : : :in the manual tuning position. : : :Confirm that your external loop is present and plugged in. : : :Take one of the . . . now semi retired . . . previous test leads w/ end clips and leave it clipped onto that pin 4 det : : :plate of the 'Q7 and take its other end and clip to a short length of insulated hook up wire . : : :That wire end is being bared of insulation, just enough to clip onto and make connection. : : :The balance of the insulated wire is to be multiple turn wound around the 1st IF transformers BLUE lead wire that routes to the 'SA7 mixer toobie. : : :(You are accomplishing low picofarads of coupling capacitance with that "gimmick" construction.) : : :SHOULD you be so fortunate as to actually have a 10-20 or so pf capacitor in stock, use that for direct interconnect. : : :(I 'm usually catering to a possibility that the requestor of info . . . quasi servicee . . hasn't a pot to pee in . . .figuratively : . . . as per parts availability on hand . . . . or more importantly . .any test equipment. ) : : :Next, use the other unused "jomping -jimminy ! " clip set to short across the primary of the 2nd IF transformer . . . .we :certainly dont wants no interstage "ossifrying"/feed back ocurring there ! : : :NOW . . . .AND NOW . . . . fire up your 'ole At-water-less Kent . .(WANNABE !) . . . and just see if some of your stronger : : :stations are coming in as you cruise across the dial scale tuning on that ole' Rota-mola ! : : : : :Standing by . . . . . . : : : : : : : : : : : : : : : : :73's de Edd : : : : : : : : : : : : :The first 90 percent of an involved task takes 90 percent of the time, with the last troublesome 10 percent taking the other 90 percent. : : : : : : |
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::Above comment assumes that the tubes have been tested and exonerated. Tubes are always the most likely suspects.
::
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I now see that the plate voltage on the 6sq7 seems out of whack. to the 470K resistor which is supplying that stages B+. at the plate of the 'Q7 to then be normal, when doing yet another retesting. |