On that sets design, and its aging, I would be leery of a marginal 1R5 since you are NOT confirming a negative voltage on its grid in its local oscillator circuitry.
Equally as suspect, confirm that the sets selenium rectifier is not limiting the available B+ being developed to the set.
If you have a Variac, I might suggest that you shunt the SR unit with a 1N4007 silicon diode and start up the set at 1/2 power with the variac and then slowly raise until the filaments approach their normal value and then check the main B+ and see if it is up from what the unit was getting with the sole selenium rectifier in the unit.
That action may then have the existing 1R5 , ossifrying again, with some stations then rolling in, and it should be quite a performer, what with that frontal RF stage and a full house, 3 section tuning capacitor used in its design.
73's de Edd
:Edd - Thanks for the suggestion, I'll try the 1N4007 shunt and let you know if it works. Dale
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:On that sets design, and its aging, I would be leery of a marginal 1R5 since you are NOT confirming a negative voltage on its grid in its local oscillator circuitry.
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:Equally as suspect, confirm that the sets selenium rectifier is not limiting the available B+ being developed to the set.
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:If you have a Variac, I might suggest that you shunt the SR unit with a 1N4007 silicon diode and start up the set at 1/2 power with the variac and then slowly raise until the filaments approach their normal value and then check the main B+ and see if it is up from what the unit was getting with the sole selenium rectifier in the unit.
:That action may then have the existing 1R5 , ossifrying again, with some stations then rolling in, and it should be quite a performer, what with that frontal RF stage and a full house, 3 section tuning capacitor used in its design.
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:73's de Edd
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:Edd - THANK YOU, THANK YOU! I shunted a silicon diode across the selenium rectifier and the B+ came up to spec value and the radio plays great. Thanks to you, I now know more than I did before. Dale
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:On that sets design, and its aging, I would be leery of a marginal 1R5 since you are NOT confirming a negative voltage on its grid in its local oscillator circuitry.
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:Equally as suspect, confirm that the sets selenium rectifier is not limiting the available B+ being developed to the set.
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:If you have a Variac, I might suggest that you shunt the SR unit with a 1N4007 silicon diode and start up the set at 1/2 power with the variac and then slowly raise until the filaments approach their normal value and then check the main B+ and see if it is up from what the unit was getting with the sole selenium rectifier in the unit.
:That action may then have the existing 1R5 , ossifrying again, with some stations then rolling in, and it should be quite a performer, what with that frontal RF stage and a full house, 3 section tuning capacitor used in its design.
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:73's de Edd
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That was basically just an initial analysis to see how the 1R5 responded.
If you now find that the unit is not hitting your sets filaments with greater than their specs, and since selenium rectifiers inherently have a quantum leap greater back resistance as compared to that silicon diode, it would be preferred..and heavy on the PREFERRED , to totally eliminate that SR from the unit and install a two lug isolated terminal strip / or / terminal stand off studs and install that '4007 alone and with it being shunted with an ~.001 ufd disc ceramic capacitor. . . spec’d at a DC WV of 500-1Kv.
I was somewhat uncertain if that initial 33 ohm current inrush resistors value would still be in order with a '4007 installed, thus the variac use, but if you can confirm its ok, so be it.
Now, isn't that little puppy really pulling them in now....or..... will be later tonight.
73's de Edd
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:That was basically just an initial analysis to see how the 1R5 responded.
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:If you now find that the unit is not hitting your sets filaments with greater than their specs, and since selenium rectifiers inherently have a quantum leap greater back resistance as compared to that silicon diode, it would be preferred..and heavy on the PREFERRED , to totally eliminate that SR from the unit and install a two lug isolated terminal strip / or / terminal stand off studs and install that '4007 alone and with it being shunted with an ~.001 ufd disc ceramic capacitor. . . spec’d at a DC WV of 500-1Kv.
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:I was somewhat uncertain if that initial 33 ohm current inrush resistors value would still be in order with a '4007 installed, thus the variac use, but if you can confirm its ok, so be it.
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:Now, isn't that little puppy really pulling them in now....or..... will be later tonight.
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:73's de Edd
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:Edd - I did totally remove the Selenium Rectifier and install just the silicon diode -- why do you suggest the ceramic capacitor across the diode? Thanks again. Dale
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:That was basically just an initial analysis to see how the 1R5 responded.
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:If you now find that the unit is not hitting your sets filaments with greater than their specs, and since selenium rectifiers inherently have a quantum leap greater back resistance as compared to that silicon diode, it would be preferred..and heavy on the PREFERRED , to totally eliminate that SR from the unit and install a two lug isolated terminal strip / or / terminal stand off studs and install that '4007 alone and with it being shunted with an ~.001 ufd disc ceramic capacitor. . . spec’d at a DC WV of 500-1Kv.
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:I was somewhat uncertain if that initial 33 ohm current inrush resistors value would still be in order with a '4007 installed, thus the variac use, but if you can confirm its ok, so be it.
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:Now, isn't that little puppy really pulling them in now....or..... will be later tonight.
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:73's de Edd
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:Edd - Oh yes, the reception is fantastic! Dale
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