marv
marv
:Forum,
:Just brought it into my shop today to restore for a neighbor. ANY SPECIAL INFO I SHOULD BE AWARE OF FROM THE PRO'S. The 2 front corners are about 36" x 6" curved columns with a fake marbled printed/painted pattern. That'll be really hard to reproduce, but at least my recent battey pack experiments will pay off again. I was amazed at the 12 inch PM speaker in a 1937 radio.
:
:marv
All Electronics often has surplus cells that might work for such applications. For bias, there is zero current draw, so shelf life is what you are most interested in.
Supposedly, those old, dead bias cells can be rejuventated by drilling a little hole, squirting in some water, and then sealing the hole. I've never tried it or much liked the idea.
Doug
:Forum,
:Please educate me on "bias cells". I'm thinking 2ea 1.5V lithium button cells, but thats 3V vs 2.7V. I measured the old ones with my B&K DMM, and got "0V", which should be accurate, since it has about 10M
:input Z, and the cells are original early 1937, but Hell, I'm early 1939 and still have a charge. lol. The 7.5V "C" batt, I'm thinking 5ea 1.5V lithium button cells or "AAA"
:
:marv
:
::Forum,
::Just brought it into my shop today to restore for a neighbor. ANY SPECIAL INFO I SHOULD BE AWARE OF FROM THE PRO'S. The 2 front corners are about 36" x 6" curved columns with a fake marbled printed/painted pattern. That'll be really hard to reproduce, but at least my recent battey pack experiments will pay off again. I was amazed at the 12 inch PM speaker in a 1937 radio.
::
::marv
Sometimes, I feel, if you can't get parts, ya has to make 'em. Do a little Google and see what kind of watch, hearing aid, whatever cell material has the longest shelf life. Then, make a "C" battery out of those, and your audio should fine and distortion free for years. Buying NOS or fooling around with cells that old sounds like a waste of time. Hell, those things are older than I, and I am older than fire.
Lewis
marv
::Marv, 3V vs. 2.7V isn't worth worrying about. Possibly just 1.5V would be OK, too?
::
::All Electronics often has surplus cells that might work for such applications. For bias, there is zero current draw, so shelf life is what you are most interested in.
::
::Supposedly, those old, dead bias cells can be rejuventated by drilling a little hole, squirting in some water, and then sealing the hole. I've never tried it or much liked the idea.
::Doug
::
:::Forum,
:::Please educate me on "bias cells". I'm thinking 2ea 1.5V lithium button cells, but thats 3V vs 2.7V. I measured the old ones with my B&K DMM, and got "0V", which should be accurate, since it has about 10M
:::input Z, and the cells are original early 1937, but Hell, I'm early 1939 and still have a charge. lol. The 7.5V "C" batt, I'm thinking 5ea 1.5V lithium button cells or "AAA"
:::
:::marv
:::
::::Forum,
::::Just brought it into my shop today to restore for a neighbor. ANY SPECIAL INFO I SHOULD BE AWARE OF FROM THE PRO'S. The 2 front corners are about 36" x 6" curved columns with a fake marbled printed/painted pattern. That'll be really hard to reproduce, but at least my recent battey pack experiments will pay off again. I was amazed at the 12 inch PM speaker in a 1937 radio.
::::
::::marv
:
:
:
:
:Sometimes, I feel, if you can't get parts, ya has to make 'em. Do a little Google and see what kind of watch, hearing aid, whatever cell material has the longest shelf life. Then, make a "C" battery out of those, and your audio should fine and distortion free for years. Buying NOS or fooling around with cells that old sounds like a waste of time. Hell, those things are older than I, and I am older than fire.
:Lewis
Marv:
whenever I HAVE to do something that departs from the original, I always try to do it in a way that can always be restored to the original radio, telephone, whatever, if the right part should be found on E-bay or in a trash can at the curb (don't laugh, it has happened). You could get around the "C" battery by putting resistors in the cathodes of the tubes, thereby biasing the grids, but I've seen so many things so totally screwed up by some "genius" trying to fix it that no one could ever restore it. Right now I am into my "telephone" mode, I have two or three in various stages of restoration, and just bought two more off of E-bay. One is perfect (for its age), the other is going into the ICU, it might be saved.
Lewis
marv
:Doug/Lewis,
:Sounds like you think like me. I believe lithiums have the longest life either in service or on the shelf, so probably use those for the bias stack and the "C" pack. If the owner wants to go to the expense (its a family heirloom), I'll try to find lithium 9 volters (15ea), so his great grand children can listen to it, otherwise alkalines. He guessed it had been 50-60 years since last powered, and all the tubes were still good, not the original RCA types, but all good old USA brands. Why can't we still produce quality products and lead the world in mfg?
:
:marv
:
:::Marv, 3V vs. 2.7V isn't worth worrying about. Possibly just 1.5V would be OK, too?
:::
:::All Electronics often has surplus cells that might work for such applications. For bias, there is zero current draw, so shelf life is what you are most interested in.
:::
:::Supposedly, those old, dead bias cells can be rejuventated by drilling a little hole, squirting in some water, and then sealing the hole. I've never tried it or much liked the idea.
:::Doug
:::
::::Forum,
::::Please educate me on "bias cells". I'm thinking 2ea 1.5V lithium button cells, but thats 3V vs 2.7V. I measured the old ones with my B&K DMM, and got "0V", which should be accurate, since it has about 10M
::::input Z, and the cells are original early 1937, but Hell, I'm early 1939 and still have a charge. lol. The 7.5V "C" batt, I'm thinking 5ea 1.5V lithium button cells or "AAA"
::::
::::marv
::::
:::::Forum,
:::::Just brought it into my shop today to restore for a neighbor. ANY SPECIAL INFO I SHOULD BE AWARE OF FROM THE PRO'S. The 2 front corners are about 36" x 6" curved columns with a fake marbled printed/painted pattern. That'll be really hard to reproduce, but at least my recent battey pack experiments will pay off again. I was amazed at the 12 inch PM speaker in a 1937 radio.
:::::
:::::marv
::
::
::
::
::Sometimes, I feel, if you can't get parts, ya has to make 'em. Do a little Google and see what kind of watch, hearing aid, whatever cell material has the longest shelf life. Then, make a "C" battery out of those, and your audio should fine and distortion free for years. Buying NOS or fooling around with cells that old sounds like a waste of time. Hell, those things are older than I, and I am older than fire.
::Lewis
marv
:Marv, 3V vs. 2.7V isn't worth worrying about. Possibly just 1.5V would be OK, too?
:
:All Electronics often has surplus cells that might work for such applications. For bias, there is zero current draw, so shelf life is what you are most interested in.
:
:Supposedly, those old, dead bias cells can be rejuventated by drilling a little hole, squirting in some water, and then sealing the hole. I've never tried it or much liked the idea.
:Doug
:
::Forum,
::Please educate me on "bias cells". I'm thinking 2ea 1.5V lithium button cells, but thats 3V vs 2.7V. I measured the old ones with my B&K DMM, and got "0V", which should be accurate, since it has about 10M
::input Z, and the cells are original early 1937, but Hell, I'm early 1939 and still have a charge. lol. The 7.5V "C" batt, I'm thinking 5ea 1.5V lithium button cells or "AAA"
::
::marv
::
:::Forum,
:::Just brought it into my shop today to restore for a neighbor. ANY SPECIAL INFO I SHOULD BE AWARE OF FROM THE PRO'S. The 2 front corners are about 36" x 6" curved columns with a fake marbled printed/painted pattern. That'll be really hard to reproduce, but at least my recent battey pack experiments will pay off again. I was amazed at the 12 inch PM speaker in a 1937 radio.
:::
:::marv
marv
:Marv, 3V vs. 2.7V isn't worth worrying about. Possibly just 1.5V would be OK, too?
:
:All Electronics often has surplus cells that might work for such applications. For bias, there is zero current draw, so shelf life is what you are most interested in.
:
:Supposedly, those old, dead bias cells can be rejuventated by drilling a little hole, squirting in some water, and then sealing the hole. I've never tried it or much liked the idea.
:Doug
:
::Forum,
::Please educate me on "bias cells". I'm thinking 2ea 1.5V lithium button cells, but thats 3V vs 2.7V. I measured the old ones with my B&K DMM, and got "0V", which should be accurate, since it has about 10M
::input Z, and the cells are original early 1937, but Hell, I'm early 1939 and still have a charge. lol. The 7.5V "C" batt, I'm thinking 5ea 1.5V lithium button cells or "AAA"
::
::marv
::
:::Forum,
:::Just brought it into my shop today to restore for a neighbor. ANY SPECIAL INFO I SHOULD BE AWARE OF FROM THE PRO'S. The 2 front corners are about 36" x 6" curved columns with a fake marbled printed/painted pattern. That'll be really hard to reproduce, but at least my recent battey pack experiments will pay off again. I was amazed at the 12 inch PM speaker in a 1937 radio.
:::
:::marv
I have a Silvertone battery set that uses a class B stage. It has a 1G4 driving a 1G6 for the output. The 1G4 uses a four bias cells in series for almost 6 volts. I tried watch batteries which had been recommended for this use. I found that the impedance of the battery is too high. The tube has the correct bias voltage on it now but it acts like it has an open grid. I did try four AA cells that were carbon zinc (Dollar store batteries) and also alkalines. The rejuvenated bias cells sounded the best. They provide a grid return to ground. My only problem is within a month, they dried out again and the voltage was lost. I have to find a better way to seal them.
Fred R
:Doug,
:Well I tested your theory, drilled a hole, put in a drop of water, let it dry, sealed it, and Eureka. The 2.7V bias cell measures 2.645V. If it lasted 70 yrs and still works, maybe another 70. As for the post looking for pix of this set, NO RESPONSE(s) yet. I'll be having crow for dinner tonite concerning the cracked case fake mica caps. The black ones looking like Smith Bros cough drops we discussed weeks ago, which several posters said were paper (including me). Not true. They are well constructed mica parts. One especially large one with several cracks was opened to see the sturdy metal core. It was quoted at 4500uufd, and measured 4570. Does anyone think I can measure, seal with with glue after heating to release any moisture and reuse all of them. The cases is soft plastic (meltable not bakelite) could be sealed with acetone too. Thinking they were paper, purchased 5% ceramics to replace all.
:
:marv
:
::Marv, 3V vs. 2.7V isn't worth worrying about. Possibly just 1.5V would be OK, too?
::
::All Electronics often has surplus cells that might work for such applications. For bias, there is zero current draw, so shelf life is what you are most interested in.
::
::Supposedly, those old, dead bias cells can be rejuventated by drilling a little hole, squirting in some water, and then sealing the hole. I've never tried it or much liked the idea.
::Doug
::
:::Forum,
:::Please educate me on "bias cells". I'm thinking 2ea 1.5V lithium button cells, but thats 3V vs 2.7V. I measured the old ones with my B&K DMM, and got "0V", which should be accurate, since it has about 10M
:::input Z, and the cells are original early 1937, but Hell, I'm early 1939 and still have a charge. lol. The 7.5V "C" batt, I'm thinking 5ea 1.5V lithium button cells or "AAA"
:::
:::marv
:::
::::Forum,
::::Just brought it into my shop today to restore for a neighbor. ANY SPECIAL INFO I SHOULD BE AWARE OF FROM THE PRO'S. The 2 front corners are about 36" x 6" curved columns with a fake marbled printed/painted pattern. That'll be really hard to reproduce, but at least my recent battey pack experiments will pay off again. I was amazed at the 12 inch PM speaker in a 1937 radio.
::::
::::marv
marv
:Marv,
:
:I have a Silvertone battery set that uses a class B stage. It has a 1G4 driving a 1G6 for the output. The 1G4 uses a four bias cells in series for almost 6 volts. I tried watch batteries which had been recommended for this use. I found that the impedance of the battery is too high. The tube has the correct bias voltage on it now but it acts like it has an open grid. I did try four AA cells that were carbon zinc (Dollar store batteries) and also alkalines. The rejuvenated bias cells sounded the best. They provide a grid return to ground. My only problem is within a month, they dried out again and the voltage was lost. I have to find a better way to seal them.
:
:Fred R
:
:
:
::Doug,
::Well I tested your theory, drilled a hole, put in a drop of water, let it dry, sealed it, and Eureka. The 2.7V bias cell measures 2.645V. If it lasted 70 yrs and still works, maybe another 70. As for the post looking for pix of this set, NO RESPONSE(s) yet. I'll be having crow for dinner tonite concerning the cracked case fake mica caps. The black ones looking like Smith Bros cough drops we discussed weeks ago, which several posters said were paper (including me). Not true. They are well constructed mica parts. One especially large one with several cracks was opened to see the sturdy metal core. It was quoted at 4500uufd, and measured 4570. Does anyone think I can measure, seal with with glue after heating to release any moisture and reuse all of them. The cases is soft plastic (meltable not bakelite) could be sealed with acetone too. Thinking they were paper, purchased 5% ceramics to replace all.
::
::marv
::
:::Marv, 3V vs. 2.7V isn't worth worrying about. Possibly just 1.5V would be OK, too?
:::
:::All Electronics often has surplus cells that might work for such applications. For bias, there is zero current draw, so shelf life is what you are most interested in.
:::
:::Supposedly, those old, dead bias cells can be rejuventated by drilling a little hole, squirting in some water, and then sealing the hole. I've never tried it or much liked the idea.
:::Doug
:::
::::Forum,
::::Please educate me on "bias cells". I'm thinking 2ea 1.5V lithium button cells, but thats 3V vs 2.7V. I measured the old ones with my B&K DMM, and got "0V", which should be accurate, since it has about 10M
::::input Z, and the cells are original early 1937, but Hell, I'm early 1939 and still have a charge. lol. The 7.5V "C" batt, I'm thinking 5ea 1.5V lithium button cells or "AAA"
::::
::::marv
::::
:::::Forum,
:::::Just brought it into my shop today to restore for a neighbor. ANY SPECIAL INFO I SHOULD BE AWARE OF FROM THE PRO'S. The 2 front corners are about 36" x 6" curved columns with a fake marbled printed/painted pattern. That'll be really hard to reproduce, but at least my recent battey pack experiments will pay off again. I was amazed at the 12 inch PM speaker in a 1937 radio.
:::::
:::::marv
For posterity purposes, you should note on the chassis what you did and date it.
:Doug,
:Well I tested your theory, drilled a hole, put in a drop of water, let it dry, sealed it, and Eureka. The 2.7V bias cell measures 2.645V. If it lasted 70 yrs and still works, maybe another 70. As for the post looking for pix of this set, NO RESPONSE(s) yet. I'll be having crow for dinner tonite concerning the cracked case fake mica caps. The black ones looking like Smith Bros cough drops we discussed weeks ago, which several posters said were paper (including me). Not true. They are well constructed mica parts. One especially large one with several cracks was opened to see the sturdy metal core. It was quoted at 4500uufd, and measured 4570. Does anyone think I can measure, seal with with glue after heating to release any moisture and reuse all of them. The cases is soft plastic (meltable not bakelite) could be sealed with acetone too. Thinking they were paper, purchased 5% ceramics to replace all.
:
:marv
:
::Marv, 3V vs. 2.7V isn't worth worrying about. Possibly just 1.5V would be OK, too?
::
::All Electronics often has surplus cells that might work for such applications. For bias, there is zero current draw, so shelf life is what you are most interested in.
::
::Supposedly, those old, dead bias cells can be rejuventated by drilling a little hole, squirting in some water, and then sealing the hole. I've never tried it or much liked the idea.
::Doug
::
:::Forum,
:::Please educate me on "bias cells". I'm thinking 2ea 1.5V lithium button cells, but thats 3V vs 2.7V. I measured the old ones with my B&K DMM, and got "0V", which should be accurate, since it has about 10M
:::input Z, and the cells are original early 1937, but Hell, I'm early 1939 and still have a charge. lol. The 7.5V "C" batt, I'm thinking 5ea 1.5V lithium button cells or "AAA"
:::
:::marv
:::
::::Forum,
::::Just brought it into my shop today to restore for a neighbor. ANY SPECIAL INFO I SHOULD BE AWARE OF FROM THE PRO'S. The 2 front corners are about 36" x 6" curved columns with a fake marbled printed/painted pattern. That'll be really hard to reproduce, but at least my recent battey pack experiments will pay off again. I was amazed at the 12 inch PM speaker in a 1937 radio.
::::
::::marv
As far as sealing the hole in the old bias cell, my first attempt would be to use silicon sealer.
This is a subject we need to get a handle on.
Doug
:Marv: Well, I'll be! I suspect that your rejuventated bias cell might last as long as most any dry cell battery you put in.
:
:For posterity purposes, you should note on the chassis what you did and date it.
:
:
::Doug,
::Well I tested your theory, drilled a hole, put in a drop of water, let it dry, sealed it, and Eureka. The 2.7V bias cell measures 2.645V. If it lasted 70 yrs and still works, maybe another 70. As for the post looking for pix of this set, NO RESPONSE(s) yet. I'll be having crow for dinner tonite concerning the cracked case fake mica caps. The black ones looking like Smith Bros cough drops we discussed weeks ago, which several posters said were paper (including me). Not true. They are well constructed mica parts. One especially large one with several cracks was opened to see the sturdy metal core. It was quoted at 4500uufd, and measured 4570. Does anyone think I can measure, seal with with glue after heating to release any moisture and reuse all of them. The cases is soft plastic (meltable not bakelite) could be sealed with acetone too. Thinking they were paper, purchased 5% ceramics to replace all.
::
::marv
::
:::Marv, 3V vs. 2.7V isn't worth worrying about. Possibly just 1.5V would be OK, too?
:::
:::All Electronics often has surplus cells that might work for such applications. For bias, there is zero current draw, so shelf life is what you are most interested in.
:::
:::Supposedly, those old, dead bias cells can be rejuventated by drilling a little hole, squirting in some water, and then sealing the hole. I've never tried it or much liked the idea.
:::Doug
:::
::::Forum,
::::Please educate me on "bias cells". I'm thinking 2ea 1.5V lithium button cells, but thats 3V vs 2.7V. I measured the old ones with my B&K DMM, and got "0V", which should be accurate, since it has about 10M
::::input Z, and the cells are original early 1937, but Hell, I'm early 1939 and still have a charge. lol. The 7.5V "C" batt, I'm thinking 5ea 1.5V lithium button cells or "AAA"
::::
::::marv
::::
:::::Forum,
:::::Just brought it into my shop today to restore for a neighbor. ANY SPECIAL INFO I SHOULD BE AWARE OF FROM THE PRO'S. The 2 front corners are about 36" x 6" curved columns with a fake marbled printed/painted pattern. That'll be really hard to reproduce, but at least my recent battey pack experiments will pay off again. I was amazed at the 12 inch PM speaker in a 1937 radio.
:::::
:::::marv
marv
:Marv: Well, I'll be! I suspect that your rejuventated bias cell might last as long as most any dry cell battery you put in.
:
:For posterity purposes, you should note on the chassis what you did and date it.
:
:
::Doug,
::Well I tested your theory, drilled a hole, put in a drop of water, let it dry, sealed it, and Eureka. The 2.7V bias cell measures 2.645V. If it lasted 70 yrs and still works, maybe another 70. As for the post looking for pix of this set, NO RESPONSE(s) yet. I'll be having crow for dinner tonite concerning the cracked case fake mica caps. The black ones looking like Smith Bros cough drops we discussed weeks ago, which several posters said were paper (including me). Not true. They are well constructed mica parts. One especially large one with several cracks was opened to see the sturdy metal core. It was quoted at 4500uufd, and measured 4570. Does anyone think I can measure, seal with with glue after heating to release any moisture and reuse all of them. The cases is soft plastic (meltable not bakelite) could be sealed with acetone too. Thinking they were paper, purchased 5% ceramics to replace all.
::
::marv
::
:::Marv, 3V vs. 2.7V isn't worth worrying about. Possibly just 1.5V would be OK, too?
:::
:::All Electronics often has surplus cells that might work for such applications. For bias, there is zero current draw, so shelf life is what you are most interested in.
:::
:::Supposedly, those old, dead bias cells can be rejuventated by drilling a little hole, squirting in some water, and then sealing the hole. I've never tried it or much liked the idea.
:::Doug
:::
::::Forum,
::::Please educate me on "bias cells". I'm thinking 2ea 1.5V lithium button cells, but thats 3V vs 2.7V. I measured the old ones with my B&K DMM, and got "0V", which should be accurate, since it has about 10M
::::input Z, and the cells are original early 1937, but Hell, I'm early 1939 and still have a charge. lol. The 7.5V "C" batt, I'm thinking 5ea 1.5V lithium button cells or "AAA"
::::
::::marv
::::
:::::Forum,
:::::Just brought it into my shop today to restore for a neighbor. ANY SPECIAL INFO I SHOULD BE AWARE OF FROM THE PRO'S. The 2 front corners are about 36" x 6" curved columns with a fake marbled printed/painted pattern. That'll be really hard to reproduce, but at least my recent battey pack experiments will pay off again. I was amazed at the 12 inch PM speaker in a 1937 radio.
:::::
:::::marv
You could try pulling tubes one at a time and see if you can pinpoint the stage it's coming from.
Doug
:Doug,
:New query. Got a symptom like described as silver mica disease, but this set is early '37. Sounds like rushing water/rain, but not constant. Have not opened the IF cans, but suspect I'll find leaded/fixed mica caps inside. Any suggestions?
:
:marv
:
marv
:Hmmm. Could be a bad connection somewhere or tube sockets that need to be cleaned?
:
:You could try pulling tubes one at a time and see if you can pinpoint the stage it's coming from.
:Doug
:
:
::Doug,
::New query. Got a symptom like described as silver mica disease, but this set is early '37. Sounds like rushing water/rain, but not constant. Have not opened the IF cans, but suspect I'll find leaded/fixed mica caps inside. Any suggestions?
::
::marv
::
:
I do notice that the two IF xfmrs are slug tuned with fixed caps. You could replace the fixed IF caps with silver-mica caps just for grins.
You might try removing the two dial lamps to see if that somehow eliminates the problem. If it does, then suspect something wrong with the dial lamp switch.
I don't know about the CW vs. CCW convention for tuning knobs. Of course, increasing frequency corresponds to decreasing wavelength.
Doug
:Doug,
:The noise wasn't constant, but did use a wire brush this AM to clean all the socket contacts. The noise came and went several times last night, and seemed to hang around after pushing in the tuning knob (turns on the dial light) in the filament string. I assume you agree that this old set wouldn't have the open frame mica disks subject to the disease. Strange thing about this set is the tuning. I'm accustomed to tuning knob CW as the freq increases and CCW down on the freq dial, but this set is opposite. It has a flat tuning belt, but a round one w/half twist would fix that. Do you find this a little unusual too?
:
:marv
:
::Hmmm. Could be a bad connection somewhere or tube sockets that need to be cleaned?
::
::You could try pulling tubes one at a time and see if you can pinpoint the stage it's coming from.
::Doug
::
::
:::Doug,
:::New query. Got a symptom like described as silver mica disease, but this set is early '37. Sounds like rushing water/rain, but not constant. Have not opened the IF cans, but suspect I'll find leaded/fixed mica caps inside. Any suggestions?
:::
:::marv
:::
::
marv
:Marv - I agree, this couldn't be any form of the silver-mica disease, at least as that disease is commonly understood. Anyway, the symptom of the silver-mica disease is loud crashing when B+ from one stage gets through to the grid on the next stage.
:
:I do notice that the two IF xfmrs are slug tuned with fixed caps. You could replace the fixed IF caps with silver-mica caps just for grins.
:
:You might try removing the two dial lamps to see if that somehow eliminates the problem. If it does, then suspect something wrong with the dial lamp switch.
:
:I don't know about the CW vs. CCW convention for tuning knobs. Of course, increasing frequency corresponds to decreasing wavelength.
:Doug
:
::Doug,
::The noise wasn't constant, but did use a wire brush this AM to clean all the socket contacts. The noise came and went several times last night, and seemed to hang around after pushing in the tuning knob (turns on the dial light) in the filament string. I assume you agree that this old set wouldn't have the open frame mica disks subject to the disease. Strange thing about this set is the tuning. I'm accustomed to tuning knob CW as the freq increases and CCW down on the freq dial, but this set is opposite. It has a flat tuning belt, but a round one w/half twist would fix that. Do you find this a little unusual too?
::
::marv
::
:::Hmmm. Could be a bad connection somewhere or tube sockets that need to be cleaned?
:::
:::You could try pulling tubes one at a time and see if you can pinpoint the stage it's coming from.
:::Doug
:::
:::
::::Doug,
::::New query. Got a symptom like described as silver mica disease, but this set is early '37. Sounds like rushing water/rain, but not constant. Have not opened the IF cans, but suspect I'll find leaded/fixed mica caps inside. Any suggestions?
::::
::::marv
::::
:::
Does your variac allow you to boost the output voltage above the nominal 120V line? If so, crank it up a little and see if the oscillator runs up to a higher freq. (Increasing the voltage will improve the emission of all the tubes, including the oscillator.)
As far as your 2-7Mhz band is concerned, you ought to be able to hear WWV clearly at 5Mhz after dark. You might also hear harmonics of very strong, nearby AM broadcast stations. The fact that you are hearing just data transmissions suggests that the band is working. Try in after dark.
If a whole SW band is dead, I would suspect an open coil connection or touching plates on the oscillator tuner.
If you have a signal generator, you could use it to verify reception on different bands.
Doug
:Doug,
:Nuther question. The band "C" 6-22 mHz osc (1C6)seemed to die around 15 mHz. Don't have counter or gen, but was able to confirm on my scope. Increased the value of C14 to 150uufd with a little help, but thinking I should up the value of R4 and return C14 to orig. value. Its difficult to test the SW bands w/airwaves only, but did get WWV and Bejing a couple times around 10 mHz. What site offers propagation data (time/date/freq/meters) for DX'ers. I suppose Thomas's favorite V-Doublet is preferred to my single wire forming a 90 degree V of approx. 40 ft overhead in my garage for SW. Set also has 2-7 mHz band, but get nothing on it, except what sounds like fax transmissions. Still looking for a .jpg of this set to define req'd decals.
:
:marv
:
This could be a red herring, but depending on the input impedance of your 'scope, including the leads, the 'scope itself could be throwing the oscillator for a loop at higher freqs.
Does this set have an RF stage ahead of the mixer? Sometimes they quit at higher freq - due to inter-electrode capacitance, not low emission.
But still, my best guess is a weak oscillator/mixer tube.
Doug
:Marv - if the oscillator poops out toward the high end of the band, chances are it's a weak oscillator tube.
:
:Does your variac allow you to boost the output voltage above the nominal 120V line? If so, crank it up a little and see if the oscillator runs up to a higher freq. (Increasing the voltage will improve the emission of all the tubes, including the oscillator.)
:
:As far as your 2-7Mhz band is concerned, you ought to be able to hear WWV clearly at 5Mhz after dark. You might also hear harmonics of very strong, nearby AM broadcast stations. The fact that you are hearing just data transmissions suggests that the band is working. Try in after dark.
:
:If a whole SW band is dead, I would suspect an open coil connection or touching plates on the oscillator tuner.
:
:If you have a signal generator, you could use it to verify reception on different bands.
:Doug
:
::Doug,
::Nuther question. The band "C" 6-22 mHz osc (1C6)seemed to die around 15 mHz. Don't have counter or gen, but was able to confirm on my scope. Increased the value of C14 to 150uufd with a little help, but thinking I should up the value of R4 and return C14 to orig. value. Its difficult to test the SW bands w/airwaves only, but did get WWV and Bejing a couple times around 10 mHz. What site offers propagation data (time/date/freq/meters) for DX'ers. I suppose Thomas's favorite V-Doublet is preferred to my single wire forming a 90 degree V of approx. 40 ft overhead in my garage for SW. Set also has 2-7 mHz band, but get nothing on it, except what sounds like fax transmissions. Still looking for a .jpg of this set to define req'd decals.
::
::marv
::
:
marv
:OK, I didn't notice that you don't have a signal generator.
:
:This could be a red herring, but depending on the input impedance of your 'scope, including the leads, the 'scope itself could be throwing the oscillator for a loop at higher freqs.
:
:Does this set have an RF stage ahead of the mixer? Sometimes they quit at higher freq - due to inter-electrode capacitance, not low emission.
:
:But still, my best guess is a weak oscillator/mixer tube.
:Doug
:
::Marv - if the oscillator poops out toward the high end of the band, chances are it's a weak oscillator tube.
::
::Does your variac allow you to boost the output voltage above the nominal 120V line? If so, crank it up a little and see if the oscillator runs up to a higher freq. (Increasing the voltage will improve the emission of all the tubes, including the oscillator.)
::
::As far as your 2-7Mhz band is concerned, you ought to be able to hear WWV clearly at 5Mhz after dark. You might also hear harmonics of very strong, nearby AM broadcast stations. The fact that you are hearing just data transmissions suggests that the band is working. Try in after dark.
::
::If a whole SW band is dead, I would suspect an open coil connection or touching plates on the oscillator tuner.
::
::If you have a signal generator, you could use it to verify reception on different bands.
::Doug
::
:::Doug,
:::Nuther question. The band "C" 6-22 mHz osc (1C6)seemed to die around 15 mHz. Don't have counter or gen, but was able to confirm on my scope. Increased the value of C14 to 150uufd with a little help, but thinking I should up the value of R4 and return C14 to orig. value. Its difficult to test the SW bands w/airwaves only, but did get WWV and Bejing a couple times around 10 mHz. What site offers propagation data (time/date/freq/meters) for DX'ers. I suppose Thomas's favorite V-Doublet is preferred to my single wire forming a 90 degree V of approx. 40 ft overhead in my garage for SW. Set also has 2-7 mHz band, but get nothing on it, except what sounds like fax transmissions. Still looking for a .jpg of this set to define req'd decals.
:::
:::marv
:::
::
marv
:Doug,
:All weak tubes were replaced and it does have an RF stage, but was only scope'ing the osc stage at the G3/G5 pin on the 1C6 w/10x/12.5uufd probe. Its batts only, and am not using a power supply for the 135VDC plate supply. Tuning condenser tests good thru entire rotation. Maybe So. CA Orange county area is just a dead zone for the for 2-30 mHz bands.
:
:marv
:
::OK, I didn't notice that you don't have a signal generator.
::
::This could be a red herring, but depending on the input impedance of your 'scope, including the leads, the 'scope itself could be throwing the oscillator for a loop at higher freqs.
::
::Does this set have an RF stage ahead of the mixer? Sometimes they quit at higher freq - due to inter-electrode capacitance, not low emission.
::
::But still, my best guess is a weak oscillator/mixer tube.
::Doug
::
:::Marv - if the oscillator poops out toward the high end of the band, chances are it's a weak oscillator tube.
:::
:::Does your variac allow you to boost the output voltage above the nominal 120V line? If so, crank it up a little and see if the oscillator runs up to a higher freq. (Increasing the voltage will improve the emission of all the tubes, including the oscillator.)
:::
:::As far as your 2-7Mhz band is concerned, you ought to be able to hear WWV clearly at 5Mhz after dark. You might also hear harmonics of very strong, nearby AM broadcast stations. The fact that you are hearing just data transmissions suggests that the band is working. Try in after dark.
:::
:::If a whole SW band is dead, I would suspect an open coil connection or touching plates on the oscillator tuner.
:::
:::If you have a signal generator, you could use it to verify reception on different bands.
:::Doug
:::
::::Doug,
::::Nuther question. The band "C" 6-22 mHz osc (1C6)seemed to die around 15 mHz. Don't have counter or gen, but was able to confirm on my scope. Increased the value of C14 to 150uufd with a little help, but thinking I should up the value of R4 and return C14 to orig. value. Its difficult to test the SW bands w/airwaves only, but did get WWV and Bejing a couple times around 10 mHz. What site offers propagation data (time/date/freq/meters) for DX'ers. I suppose Thomas's favorite V-Doublet is preferred to my single wire forming a 90 degree V of approx. 40 ft overhead in my garage for SW. Set also has 2-7 mHz band, but get nothing on it, except what sounds like fax transmissions. Still looking for a .jpg of this set to define req'd decals.
::::
::::marv
::::
:::
http://www.nostalgiaair.org/References/lamps/
There's a table of lamps. Some are 2 volts. One is probably the one you need.
I hope that this helps,
Dave
:Can anyone cross a Mazda bulb DA-MA20A to a modern equiv? Its across the 2V filament for dial lights.
:
:marv
:
::Doug,
::All weak tubes were replaced and it does have an RF stage, but was only scope'ing the osc stage at the G3/G5 pin on the 1C6 w/10x/12.5uufd probe. Its batts only, and am not using a power supply for the 135VDC plate supply. Tuning condenser tests good thru entire rotation. Maybe So. CA Orange county area is just a dead zone for the for 2-30 mHz bands.
::
::marv
::
:::OK, I didn't notice that you don't have a signal generator.
:::
:::This could be a red herring, but depending on the input impedance of your 'scope, including the leads, the 'scope itself could be throwing the oscillator for a loop at higher freqs.
:::
:::Does this set have an RF stage ahead of the mixer? Sometimes they quit at higher freq - due to inter-electrode capacitance, not low emission.
:::
:::But still, my best guess is a weak oscillator/mixer tube.
:::Doug
:::
::::Marv - if the oscillator poops out toward the high end of the band, chances are it's a weak oscillator tube.
::::
::::Does your variac allow you to boost the output voltage above the nominal 120V line? If so, crank it up a little and see if the oscillator runs up to a higher freq. (Increasing the voltage will improve the emission of all the tubes, including the oscillator.)
::::
::::As far as your 2-7Mhz band is concerned, you ought to be able to hear WWV clearly at 5Mhz after dark. You might also hear harmonics of very strong, nearby AM broadcast stations. The fact that you are hearing just data transmissions suggests that the band is working. Try in after dark.
::::
::::If a whole SW band is dead, I would suspect an open coil connection or touching plates on the oscillator tuner.
::::
::::If you have a signal generator, you could use it to verify reception on different bands.
::::Doug
::::
:::::Doug,
:::::Nuther question. The band "C" 6-22 mHz osc (1C6)seemed to die around 15 mHz. Don't have counter or gen, but was able to confirm on my scope. Increased the value of C14 to 150uufd with a little help, but thinking I should up the value of R4 and return C14 to orig. value. Its difficult to test the SW bands w/airwaves only, but did get WWV and Bejing a couple times around 10 mHz. What site offers propagation data (time/date/freq/meters) for DX'ers. I suppose Thomas's favorite V-Doublet is preferred to my single wire forming a 90 degree V of approx. 40 ft overhead in my garage for SW. Set also has 2-7 mHz band, but get nothing on it, except what sounds like fax transmissions. Still looking for a .jpg of this set to define req'd decals.
:::::
:::::marv
:::::
::::
marv
:Marv,
: Take a look at this page:
:
:http://www.nostalgiaair.org/References/lamps/
:
:There's a table of lamps. Some are 2 volts. One is probably the one you need.
:
:I hope that this helps,
:
:Dave
::Can anyone cross a Mazda bulb DA-MA20A to a modern equiv? Its across the 2V filament for dial lights.
::
::marv
::
:::Doug,
:::All weak tubes were replaced and it does have an RF stage, but was only scope'ing the osc stage at the G3/G5 pin on the 1C6 w/10x/12.5uufd probe. Its batts only, and am not using a power supply for the 135VDC plate supply. Tuning condenser tests good thru entire rotation. Maybe So. CA Orange county area is just a dead zone for the for 2-30 mHz bands.
:::
:::marv
:::
::::OK, I didn't notice that you don't have a signal generator.
::::
::::This could be a red herring, but depending on the input impedance of your 'scope, including the leads, the 'scope itself could be throwing the oscillator for a loop at higher freqs.
::::
::::Does this set have an RF stage ahead of the mixer? Sometimes they quit at higher freq - due to inter-electrode capacitance, not low emission.
::::
::::But still, my best guess is a weak oscillator/mixer tube.
::::Doug
::::
:::::Marv - if the oscillator poops out toward the high end of the band, chances are it's a weak oscillator tube.
:::::
:::::Does your variac allow you to boost the output voltage above the nominal 120V line? If so, crank it up a little and see if the oscillator runs up to a higher freq. (Increasing the voltage will improve the emission of all the tubes, including the oscillator.)
:::::
:::::As far as your 2-7Mhz band is concerned, you ought to be able to hear WWV clearly at 5Mhz after dark. You might also hear harmonics of very strong, nearby AM broadcast stations. The fact that you are hearing just data transmissions suggests that the band is working. Try in after dark.
:::::
:::::If a whole SW band is dead, I would suspect an open coil connection or touching plates on the oscillator tuner.
:::::
:::::If you have a signal generator, you could use it to verify reception on different bands.
:::::Doug
:::::
::::::Doug,
::::::Nuther question. The band "C" 6-22 mHz osc (1C6)seemed to die around 15 mHz. Don't have counter or gen, but was able to confirm on my scope. Increased the value of C14 to 150uufd with a little help, but thinking I should up the value of R4 and return C14 to orig. value. Its difficult to test the SW bands w/airwaves only, but did get WWV and Bejing a couple times around 10 mHz. What site offers propagation data (time/date/freq/meters) for DX'ers. I suppose Thomas's favorite V-Doublet is preferred to my single wire forming a 90 degree V of approx. 40 ft overhead in my garage for SW. Set also has 2-7 mHz band, but get nothing on it, except what sounds like fax transmissions. Still looking for a .jpg of this set to define req'd decals.
::::::
::::::marv
::::::
:::::