If the radio has more than two wires coming out the back, then this radio more likely uses A/B batteries. A lack of power transformer and vibrator will also tell this. Then, what's needed are the tube types. Knowing what circuits they are used in, and how the filaments are wired, in series or parallel, or some variation there-of, will tell what kind of A battery to use. Knowing whether separate B batteries, and possibly even a C battery, were used or not, will tell what kind of B batteries to use, depending on the tubes used, and what circuits are employed. Wish I could find a schematic for this radio. Perhaps someone else can.
T.
A red wire from radio goes to say prong 1 of 3pp-A. A wire (yellow) attached to prong 2 of 3pp-A goes to prong 1 of 3pp-B. A black wire attached to prong 2 of 3pp-B goes back to radio.
A yellowish wire from radio goes to prong 1 of 2pp-C. A yelow wire from prong 2 of 2pp-C goes to prong 1 of 3pp-D. An orange wire also connected to prong 1 of 3pp-D returns to radio. A yellow wire from prong 2 of 3pp-D goes to prong 1 of 3pp-E. A green wire from prong 2 of 3pp-E returns to radio.
My guess is that plugs A&B are connected in series with two seperate but identical batteries (voltage?)and that plug C is connected to a different battery (voltage?).
Your thoughts!!!
Does this radio have a tube diagram (where they go)? If so, then I could get a general idea of the filament wiring connections, and then I could ask you to see if the filaments are wired in series or parallel.
Thomas
:When looking from the back of the radio, and moving from right to left, there is a black device "Hammond 368", a tube made for canadian Marconi J8 - "IG6 GT/G", a "Hammond 334", two J8 - "IG4 GT" tubes, a round metal device with wire from top into chassis, a square device "#S-104 2nd IF 455 KC", a round metal device with wire from top into adjacent square device "#S-103 1st IF 455 KC". Then there are 2 more round metal devices with top wires going into chassis, 2 unmarked different but identical square devices, 1 unmarked and different square device and finally the tuning device.
Are there only 3 tubes in this radio? The tubes you list are 1.4 volt tubes, a 1.5 volt battery would be used for the filaments. You can verify the filament plug by tracing the wire to the filament pins of the tubes. Tube data is available under tubes on this website.
The B+ is probably 90 volts, often achieved by using two 45 volt B batteries or one 90 volt battery. You could test the radio using those voltages, just be sure not to mix up the filament wiring with the B+ as you will blow the tubes.
Ed.
Thomas
Thomas
:Hi Don,
:
:Are there only 3 tubes in this radio? The tubes you list are 1.4 volt tubes, a 1.5 volt battery would be used for the filaments. You can verify the filament plug by tracing the wire to the filament pins of the tubes. Tube data is available under tubes on this website.
:
:The B+ is probably 90 volts, often achieved by using two 45 volt B batteries or one 90 volt battery. You could test the radio using those voltages, just be sure not to mix up the filament wiring with the B+ as you will blow the tubes.
:
:Ed.
Hi Thomas,
Just an appology from the "idiot" who came in and made a statement on YOUR forum.
You seem to delight in taking up much bandwidth in lenghty tutorials whether or not they are required. Your idiot comment brings this forum down to the level of another forum that is noted for comments like yours.
Idiot.
Thomas
:Hi Thomas,
:
:Just an appology from the "idiot" who came in and made a statement on YOUR forum.
:
:You seem to delight in taking up much bandwidth in lenghty tutorials whether or not they are required. Your idiot comment brings this forum down to the level of another forum that is noted for comments like yours.
:
:Idiot.
Hi Thomas,
Thank you for the explanations of what was wrong with my suggestions. Now please bear with me while I explain why it was made.
I determined from the first posting that the radio was a console battery radio with the brand name of Chisholm. A search indicated that this brand was not in Riders but was listed with two models of a later vintage in the RCC index. (Radio College of Canada) That along with the data that Marconi tubes were used indicated that the radio may have had an origin here in Canada and quite possibly may have been a retailers brand name made by one of the manufacturers here that made radios for department stores etc.
The 3 tubes listed indicated that the radio was probably a "farm" radio using 1.5 volts A and 90 volts B power. The are common here and in my experience typically have parallel connected filaments rather than series.
The question asking if there were only 3 tubes in the radio was asked to determine if there were additional tubes or if some tubes were missing. I know the radio will not function on those 3 tubes. If I could determine the type and number of tubes used I can consult MYE Canada (Mallory Yaxley Radio Encyclopia) and manually search their listings of tubes used in various models of radios. This may lead us to a schematic is one was published. It is easier for all of us to visualize this radio design if we can look at a schematic.
Don's description of the plug wiring indicated that he has basic knowlege of wiring (series/parallel hook ups) and that the plugs and external wiring on this radio appear to be non-standard. They remind one of older battery radios that used a "C" battery also.
That is why I made the recommendation to trace the wiring back to the tube filaments. Lets give Don some credit and allow him to ask for assistance in doing this if he is confused or not comfortable doing it. He can be walked through it on or off forum. It is possible that Don may have to get into the chassis wiring anyways if there is a problem and there is a high possibility that some capacitors may have to be replaced.
It is interesting to note that in your later postings, after your vacuum tube tutorial you recommend "tracing the plug wiring back to the tube filaments". Same suggestion as mine but wrong for me to suggest and right for you to suggest. WHY? I made no mention of hooking up voltages other than those two and a caution was given about the 90 volts and the "B" circuit.
We could be even more practical and say connect 1.5 volts to one of the sets of plugs. Assuming that the tubes are wired in parallel, that the switch is on and there are no problems the tubes should light if that is the "A" circuit. If they do not light try the other plug to see if it is the "A" circuit. Hooking 1.5 volts to the "B" circuit should do no harm. Also hooking up 1.5 volts to the filaments if they were wired in series would do no harm. Only polarity would then have to be sorted out.
As I see it both our recommendations to determine the plug wiring are similar except in length. I seldom give advice in forums but when I do it is based on experience and I like to make it practical and short. I avoid details that may not be necessary and try to avoid name calling, criticism and postings that have a condescending tone to them.
Why don't we quit critiquing each other's postings and let the forum be what it is supposed to be. A place where opinions can be expressed freely and where the person asking for those opinions can choose which ones he cares to pursue.
One question I have is that there must be others in this forum with experience in battery radios, where are your suggestions?
My appologies for being long winded.
Ed Kraushar, the idiot.
Well put Ed
In the wiring bundle the red and black go through two odd plugs in a series manner. I am sure I can rig up some connection but the voltage is in question? If we are talking xx volts, would the connections be red to positive and black to negative?
In your discussions, there is reference to a filament requiring a different voltage. That would account for the remaining pair of connections. A filament would heat in either direction of electron movement therefore no issue on positive or negative, Yes/NO ?
You do have 7 tubes, and from the looks of it, quite the portable radio. Those 1G4GT tubes should be 1G5GT tubes. This will be hard to explain to you now, since you don't know much about radio yet, but you will understand it better later. The 1G4GT is a triode tube. It has three elements: a cathode, control grid, and a plate. This is a basic amplifier tube. The 1G5GT is a pentode. It has a cathode, control grid, accelerator/screen grid, supressor grid, and a plate. The basically needed elements, the cathode, control grid, and the plate, are connected to the same pins in both tubes. The plus of the 1G5GT is that it has the screen and supressor grids, which make it a stronger amplifying tube. The 1G5GT tubes are used in a special push-pull arrangement for the audio output of your set. Push-pull is a special type of amplification that uses two tubes out of phase with eachother to drive the speaker. Its fidelity is far superior to a single tube driven speaker. Your high end amplifiers in old consol radios and in your modern car/household stereo use push-pull amplification (your stereo is likely transistorized, but the effect is exactly the same). It is rich and enjoyable. When you get the chance, switch the tubes to 1G5GT tubes. For now, though, you will probably be able to get the set running well with the 1G4GT tubes. The set may sound incredibly good with the 1G4GT tubes as well as the 1G5GT tubes. I suspect that it will be a bit louder with the 1G5GT tubes. Do not expect the fidelity of your household stereo from this radio, as it is a portable, and probably is AM only (broadcast and perhaps some short wave bands). Since it is AM only, it is not meant to be super high fidelity anyway, as you don't want to hear the full sound range with AM. This only allows you to hear distortion and static. The bass response of this radio will exceed that of an ordinary portable, though, and the sound won't be as harsh. The treble notes, if allowed through somewhat, will be much truer and not too muffled.
At any rate, I will go down the list of tubes for you and let you know what they are.
2nd black Hammond device is likely the output transformer that feeds the speaker, unless the speaker has its own output transformer.
1G5GT x 2.......pentode output tubes for push-pull amplification.
1G6GT ..........twin triode audio preamplifier tube...one triode for each phase of the push-pull output.
1H5GT ..........triode for audio preamplification prior to the 1G6GT. One of the Hammond transformers is likely the audio interstage transformer between this tube and the 1G6GT. The Hammond transformer splits the audio into two diametrically opposed phases. Another section of the 1H5GT is a diode (two elements...cathode and plate). Serves to rectify the radio frequency signal and detect the audio from this signal.
1P5GT ..........radio frequency pentode, amplifies prior to the 2nd IF transformer, receives signal from 1st IF transformer (intermediate frequency)....cap on top of tube is the terminal of the control grid of this tube. By placing this terminal away from the others, it is isolated from interferance.
1A7GT ..........heptode (7 grid) local radio frequency oscillator/radio frequency modulator...combines locally generated frequency (local as in within the radio...by the 1A7 tube) with the incoming radio frequency, and sends it to the 1st IF transformer. This tube is a bit complicated in operation. I will explain its operation some other time if you wish.
1P5GT ..........RF preamplifier tube....preamplifies incoming signal before sending it to the modulator.
The way a tube works is it has a heated cathode. With AC radios an AC current is used to heat this cathode. Since this AC current would introduce interferance and hum, the cathode, if directly heated--basically a filament, is made very thick, or if indirectly heated, is a filament within a metal tube that serves as the cathode. The filament in the tube heats the tube. The tube, serving as the cathode, is actually what emits electrons in this type of tube. For battery radios, though, the first concern is battery drainage. The former filaments are too thick, and draw too much current--they would drain a battery very quickly. Since a heavy filament is not needed with direct current use, a very thin one can be used. No metal cylinder is needed to isolate the filament from the cathode voltage, so none is used. The filament is very thin and draws very little current. When it is lit, you can barely see it. Typically, with the more modern "octal" (8 pin) tubes, the tube's first number designates its voltage. 1G4GT has a 1.5 volt filament. The filament serves as the cathode in these small battery type tubes.
The second element in a diode tube is the plate. This is a metal cylinder that surrounds the cathode. The cathode, when heated, shakes electrons loose due to the heat. These negative electrons flow towards the plate. If a battery is connected so that its negative side is connected to the cathode and its positive side is connected to the plate, negative electrons will flow from the cathode to the plate. Keep in mind that while this is happening, another battery is lighting the cathode (filament). Between the cathode and the plate is practically nothing--it's a vacuum.
Now, this is a simple diode described above. For amplification purposes, a third element can be placed in a tube, making it a triode. The element is a control grid. It is called a grid because it really looks like a grid. It's basically a specially formed spiral of wire. It looks like a screen in a way. This grid is placed between the cathode and the plate. Something very special can be accomplished with this grid. An extremely small negative charge on the grid can almost stop (and sometimes does stop if the charge is strong enough) the electron flow from cathode to plate. An extremely small positive charge on the grid can excite electron flow to the plate. An extremely small charge of any type on the grid can make a very radical change in electron flow to the plate. By this special characteristic, a tube can be used to amplify a signal. It does not really amplify a signal, but seems to. Basically a tube is used as a controlling device. A very weak signal is applied across the grid and cathode. The signal causes the grid to go ever so slightly more or less negative than the cathode, which radically changes the electron flow from cathode to plate. These radical changes are seen at the plate as a stronger signal. If sent to another tube, the signal may be made stronger still. Typically, in high quality amplifiers, the grid never really goes positive, but is always kept negative. A signal imposed upon it changes this negativity. The reason it must stay negative is because when it is negative, it affects the electrons emitted from the cathode, but the electrons do not collect on the grid. If the grid were allowed to go positive, electrons would flow to the grid instead of the plate, which would throw off the liniarity of the tube's response, and would introduce distortion to the signal.
With a pentode, two more grids are added that are charged with a steady voltage. One grid, after the control grid, is charged positively...almost as positively as the plate. This grid serves to excite electron flow, which makes the tube a stronger amplifier. A third grid is placed after this "screen" grid. It is called a supressor grid. This grid is charged as negatively as the cathode. Since electrons fly at the plate at a much faster rate due to the screen grid, they have a tendency to bounce off the plate and go elsewhere in the tube, which causes interferance. This negatively charged grid keeps the electrons from bouncing off the plate--it repels them back at the plate. You would think that the positively charged screen grid would keep all the electrons for itself, or that the negatively charged supressor grid would stop all electron flow, but as a grid gets farther from the cathode, it has less affect on the electrons. These grids have far less influence on the electrons than the control grid.
As for how the plate sends its information to the next tube or device, a resistor may be connected between it and the positive current source, thereby limiting how much current the plate can see. A strong current of electrons from the cathode would make the plate less positive. A capacitor connected between the plate and the next amplification stage will transfer these changes to the next stage. Another method has the primary coil of a transformer connected in series with the plate and the positive current source. Changes in plate load on this coil induce magnetic fields. A second coil in the transformer senses these magnetic changes, and generates a corresponding current which is fed to the next stage.
At any rate, that said, the filaments I am talking about are those within the tubes. They must be lit by a special low voltage battery called an A battery. The cathode to plate voltage must be supplied by a different high voltage B battery. Usually the B battery for a portable radio like your's is around 67.5 to 90 volts. If the filaments of your radio are wired in parallel, then they would require a 1.5 volt A battery. If they are wired in series, which sometimes is the case, then they would require a 10.5 volt battery. In either case, they must be correctly connected as the A battery voltage does have some affect on how the radio performs, especially if the filaments are wired in series. The A voltage sort-of adds to the B voltage at each filament. The filament of one tube at one end of the string will be much more negative than a filament at the other end of the string. If in parallel, the effect is much less so. This is all thought out when the radio is designed. This difference in voltage throughout the string is used to "bias" each tube. The - wire of the B battery is usually connected somehow to the negative side of the filament string. Usually the red and black wires will be your A battery wires. Red will be the positive wire. Blue and yellow wires are often used for the B battery. Blue would be + and yellow -. This may not be the case in your radio, though. The best way to see what wires are the filament wires is to look at the base of each tube. Pins 2 and 7 are the filament pins. See if the tubes are wired in parallel or in series first. Then, see if one of the tubes has one of the battery wires connected to a filament pin. If more than one wire connects to a filament pin, then one of these wires is A- and one is B-. If parallel wired, the other side of the parallel wiring should go to a switch. If series wired, the other end of the string should go to a switch. The switch may be a two part switch, too, controlling both A and B current. Determine the two sections of the switch with your multi-meter. The wire going to the switch that connects to the filament wiring when the switch is closed will be your A+ wire. The B- wire may be directly connected to part of the filament wiring, as stated above, or it may be connected through a resistor. The B+ wire will likely go to the other part of the switch. When the switch is closed, this will connect to wiring that goes to the audio output transformer. You should get continuity (a resistance measurement of several hundred ohms) between the B+ wire and pin 3 of each of the 1G6GT output tubes. For a B battery, use either a 67.5 or 90 volt battery. When reading a tube basing diagram, the diagram is usually written looking at the underside of the tube socket.
These batteries are available at www.tubesandmore.com, which will supply you with almost all the parts and tubes you will need to get this radio working. They also sell power supplies that allow you to operate this battery radio on AC. Try connecting the A battery either way and see which way works best. Some radios like things one way and some the other. While at the www.tubesandmore.com site, you will also want to purchase David and Betty Johnson's Antique Radio Restoration Guide. This is an excellent book that will help you out with many troubles you may have.
Hopefully you can get this radio working right away by just connecting the batteries. However, condensers (capacitors) like to short out and become leaky. These are the units with MFD ratings on them (microfarad). You will learn about capacitors when you read the above book, or perhaps I can explain them to you some other time. Basically, though, if they have any leakage at all, even in the millions of ohms, they can ruin your set's operation, especially battery sets. They are very sensitive. Be very careful with battery tubes, though. The filaments are extremely easy to burn out.
Sorry for the lengthy explanation which I guess I am famous for, but you need a lot of this information if you are ever to get your radio working right and understand how it works, etc. I also wrote this after working 3rd shift, so I may have been redundant with some things.
Thomas
:UPDATE ON DETAILS
:Correct regarding my limited knowledge about radios.
:I am looking at the metal housing mounted within the radio, I did not plan to remove it at this time to try and interpret how it was wired underneath.
:I did gather a bit more information (diagram of major components) and will edit my initial description of chassis.
::When looking from the back of the radio, and moving from right to left, there is a black device "Hammond 368", a tube J8 - "IG6 GT/G", a "Hammond 334", two J8 - "IG4 GT" tubes (diagram says two IG5 GT), a round metal device (shielded tube - I pulled it out) with wire from top into chassis (diagram says IH5 GT), a square device "#S-104 2nd IF 455 KC" (diagram says IF output 455KC), a round metal device (shielded tube)(diagram says IP5 GT)with wire from top into adjacent square device "#S-103 1st IF 455 KC" (diagram says IF input 455 KC). Then there are 2 more round metal devices (shielded tubes)with top wires going into chassis (diagram says IA7 GT and IP5 GT), 2 unmarked different but identical square devices (diagram says RF Coil 540 KC and OSC Coil 600 KC), 1 unmarked and different square device (diagram says ANT Coil 540 KC)and finally the tuning device.
:
:In the wiring bundle the red and black go through two odd plugs in a series manner. I am sure I can rig up some connection but the voltage is in question? If we are talking xx volts, would the connections be red to positive and black to negative?
:
:In your discussions, there is reference to a filament requiring a different voltage. That would account for the remaining pair of connections. A filament would heat in either direction of electron movement therefore no issue on positive or negative, Yes/NO ?
:
:Well, here's the scoop:
:
:You do have 7 tubes, and from the looks of it, quite the portable radio. Those 1G4GT tubes should be 1G5GT tubes. This will be hard to explain to you now, since you don't know much about radio yet, but you will understand it better later. The 1G4GT is a triode tube. It has three elements: a cathode, control grid, and a plate. This is a basic amplifier tube. The 1G5GT is a pentode. It has a cathode, control grid, accelerator/screen grid, supressor grid, and a plate. The basically needed elements, the cathode, control grid, and the plate, are connected to the same pins in both tubes. The plus of the 1G5GT is that it has the screen and supressor grids, which make it a stronger amplifying tube. The 1G5GT tubes are used in a special push-pull arrangement for the audio output of your set. Push-pull is a special type of amplification that uses two tubes out of phase with eachother to drive the speaker. Its fidelity is far superior to a single tube driven speaker. Your high end amplifiers in old consol radios and in your modern car/household stereo use push-pull amplification (your stereo is likely transistorized, but the effect is exactly the same). It is rich and enjoyable. When you get the chance, switch the tubes to 1G5GT tubes. For now, though, you will probably be able to get the set running well with the 1G4GT tubes. The set may sound incredibly good with the 1G4GT tubes as well as the 1G5GT tubes. I suspect that it will be a bit louder with the 1G5GT tubes. Do not expect the fidelity of your household stereo from this radio, as it is a portable, and probably is AM only (broadcast and perhaps some short wave bands). Since it is AM only, it is not meant to be super high fidelity anyway, as you don't want to hear the full sound range with AM. This only allows you to hear distortion and static. The bass response of this radio will exceed that of an ordinary portable, though, and the sound won't be as harsh. The treble notes, if allowed through somewhat, will be much truer and not too muffled.
:
:At any rate, I will go down the list of tubes for you and let you know what they are.
:
:2nd black Hammond device is likely the output transformer that feeds the speaker, unless the speaker has its own output transformer.
:1G5GT x 2.......pentode output tubes for push-pull amplification.
:1G6GT ..........twin triode audio preamplifier tube...one triode for each phase of the push-pull output.
:1H5GT ..........triode for audio preamplification prior to the 1G6GT. One of the Hammond transformers is likely the audio interstage transformer between this tube and the 1G6GT. The Hammond transformer splits the audio into two diametrically opposed phases. Another section of the 1H5GT is a diode (two elements...cathode and plate). Serves to rectify the radio frequency signal and detect the audio from this signal.
:1P5GT ..........radio frequency pentode, amplifies prior to the 2nd IF transformer, receives signal from 1st IF transformer (intermediate frequency)....cap on top of tube is the terminal of the control grid of this tube. By placing this terminal away from the others, it is isolated from interferance.
:1A7GT ..........heptode (7 grid) local radio frequency oscillator/radio frequency modulator...combines locally generated frequency (local as in within the radio...by the 1A7 tube) with the incoming radio frequency, and sends it to the 1st IF transformer. This tube is a bit complicated in operation. I will explain its operation some other time if you wish.
:1P5GT ..........RF preamplifier tube....preamplifies incoming signal before sending it to the modulator.
:
:The way a tube works is it has a heated cathode. With AC radios an AC current is used to heat this cathode. Since this AC current would introduce interferance and hum, the cathode, if directly heated--basically a filament, is made very thick, or if indirectly heated, is a filament within a metal tube that serves as the cathode. The filament in the tube heats the tube. The tube, serving as the cathode, is actually what emits electrons in this type of tube. For battery radios, though, the first concern is battery drainage. The former filaments are too thick, and draw too much current--they would drain a battery very quickly. Since a heavy filament is not needed with direct current use, a very thin one can be used. No metal cylinder is needed to isolate the filament from the cathode voltage, so none is used. The filament is very thin and draws very little current. When it is lit, you can barely see it. Typically, with the more modern "octal" (8 pin) tubes, the tube's first number designates its voltage. 1G4GT has a 1.5 volt filament. The filament serves as the cathode in these small battery type tubes.
:
:The second element in a diode tube is the plate. This is a metal cylinder that surrounds the cathode. The cathode, when heated, shakes electrons loose due to the heat. These negative electrons flow towards the plate. If a battery is connected so that its negative side is connected to the cathode and its positive side is connected to the plate, negative electrons will flow from the cathode to the plate. Keep in mind that while this is happening, another battery is lighting the cathode (filament). Between the cathode and the plate is practically nothing--it's a vacuum.
:
:Now, this is a simple diode described above. For amplification purposes, a third element can be placed in a tube, making it a triode. The element is a control grid. It is called a grid because it really looks like a grid. It's basically a specially formed spiral of wire. It looks like a screen in a way. This grid is placed between the cathode and the plate. Something very special can be accomplished with this grid. An extremely small negative charge on the grid can almost stop (and sometimes does stop if the charge is strong enough) the electron flow from cathode to plate. An extremely small positive charge on the grid can excite electron flow to the plate. An extremely small charge of any type on the grid can make a very radical change in electron flow to the plate. By this special characteristic, a tube can be used to amplify a signal. It does not really amplify a signal, but seems to. Basically a tube is used as a controlling device. A very weak signal is applied across the grid and cathode. The signal causes the grid to go ever so slightly more or less negative than the cathode, which radically changes the electron flow from cathode to plate. These radical changes are seen at the plate as a stronger signal. If sent to another tube, the signal may be made stronger still. Typically, in high quality amplifiers, the grid never really goes positive, but is always kept negative. A signal imposed upon it changes this negativity. The reason it must stay negative is because when it is negative, it affects the electrons emitted from the cathode, but the electrons do not collect on the grid. If the grid were allowed to go positive, electrons would flow to the grid instead of the plate, which would throw off the liniarity of the tube's response, and would introduce distortion to the signal.
:
:With a pentode, two more grids are added that are charged with a steady voltage. One grid, after the control grid, is charged positively...almost as positively as the plate. This grid serves to excite electron flow, which makes the tube a stronger amplifier. A third grid is placed after this "screen" grid. It is called a supressor grid. This grid is charged as negatively as the cathode. Since electrons fly at the plate at a much faster rate due to the screen grid, they have a tendency to bounce off the plate and go elsewhere in the tube, which causes interferance. This negatively charged grid keeps the electrons from bouncing off the plate--it repels them back at the plate. You would think that the positively charged screen grid would keep all the electrons for itself, or that the negatively charged supressor grid would stop all electron flow, but as a grid gets farther from the cathode, it has less affect on the electrons. These grids have far less influence on the electrons than the control grid.
:
:As for how the plate sends its information to the next tube or device, a resistor may be connected between it and the positive current source, thereby limiting how much current the plate can see. A strong current of electrons from the cathode would make the plate less positive. A capacitor connected between the plate and the next amplification stage will transfer these changes to the next stage. Another method has the primary coil of a transformer connected in series with the plate and the positive current source. Changes in plate load on this coil induce magnetic fields. A second coil in the transformer senses these magnetic changes, and generates a corresponding current which is fed to the next stage.
:
:At any rate, that said, the filaments I am talking about are those within the tubes. They must be lit by a special low voltage battery called an A battery. The cathode to plate voltage must be supplied by a different high voltage B battery. Usually the B battery for a portable radio like your's is around 67.5 to 90 volts. If the filaments of your radio are wired in parallel, then they would require a 1.5 volt A battery. If they are wired in series, which sometimes is the case, then they would require a 10.5 volt battery. In either case, they must be correctly connected as the A battery voltage does have some affect on how the radio performs, especially if the filaments are wired in series. The A voltage sort-of adds to the B voltage at each filament. The filament of one tube at one end of the string will be much more negative than a filament at the other end of the string. If in parallel, the effect is much less so. This is all thought out when the radio is designed. This difference in voltage throughout the string is used to "bias" each tube. The - wire of the B battery is usually connected somehow to the negative side of the filament string. Usually the red and black wires will be your A battery wires. Red will be the positive wire. Blue and yellow wires are often used for the B battery. Blue would be + and yellow -. This may not be the case in your radio, though. The best way to see what wires are the filament wires is to look at the base of each tube. Pins 2 and 7 are the filament pins. See if the tubes are wired in parallel or in series first. Then, see if one of the tubes has one of the battery wires connected to a filament pin. If more than one wire connects to a filament pin, then one of these wires is A- and one is B-. If parallel wired, the other side of the parallel wiring should go to a switch. If series wired, the other end of the string should go to a switch. The switch may be a two part switch, too, controlling both A and B current. Determine the two sections of the switch with your multi-meter. The wire going to the switch that connects to the filament wiring when the switch is closed will be your A+ wire. The B- wire may be directly connected to part of the filament wiring, as stated above, or it may be connected through a resistor. The B+ wire will likely go to the other part of the switch. When the switch is closed, this will connect to wiring that goes to the audio output transformer. You should get continuity (a resistance measurement of several hundred ohms) between the B+ wire and pin 3 of each of the 1G6GT output tubes. For a B battery, use either a 67.5 or 90 volt battery. When reading a tube basing diagram, the diagram is usually written looking at the underside of the tube socket.
:
:These batteries are available at www.tubesandmore.com, which will supply you with almost all the parts and tubes you will need to get this radio working. They also sell power supplies that allow you to operate this battery radio on AC. Try connecting the A battery either way and see which way works best. Some radios like things one way and some the other. While at the www.tubesandmore.com site, you will also want to purchase David and Betty Johnson's Antique Radio Restoration Guide. This is an excellent book that will help you out with many troubles you may have.
:
:Hopefully you can get this radio working right away by just connecting the batteries. However, condensers (capacitors) like to short out and become leaky. These are the units with MFD ratings on them (microfarad). You will learn about capacitors when you read the above book, or perhaps I can explain them to you some other time. Basically, though, if they have any leakage at all, even in the millions of ohms, they can ruin your set's operation, especially battery sets. They are very sensitive. Be very careful with battery tubes, though. The filaments are extremely easy to burn out.
:
:Sorry for the lengthy explanation which I guess I am famous for, but you need a lot of this information if you are ever to get your radio working right and understand how it works, etc. I also wrote this after working 3rd shift, so I may have been redundant with some things.
:
:Thomas
:
:
::UPDATE ON DETAILS
::Correct regarding my limited knowledge about radios.
::I am looking at the metal housing mounted within the radio, I did not plan to remove it at this time to try and interpret how it was wired underneath.
::I did gather a bit more information (diagram of major components) and will edit my initial description of chassis.
:::When looking from the back of the radio, and moving from right to left, there is a black device "Hammond 368", a tube J8 - "IG6 GT/G", a "Hammond 334", two J8 - "IG4 GT" tubes (diagram says two IG5 GT), a round metal device (shielded tube - I pulled it out) with wire from top into chassis (diagram says IH5 GT), a square device "#S-104 2nd IF 455 KC" (diagram says IF output 455KC), a round metal device (shielded tube)(diagram says IP5 GT)with wire from top into adjacent square device "#S-103 1st IF 455 KC" (diagram says IF input 455 KC). Then there are 2 more round metal devices (shielded tubes)with top wires going into chassis (diagram says IA7 GT and IP5 GT), 2 unmarked different but identical square devices (diagram says RF Coil 540 KC and OSC Coil 600 KC), 1 unmarked and different square device (diagram says ANT Coil 540 KC)and finally the tuning device.
::
::In the wiring bundle the red and black go through two odd plugs in a series manner. I am sure I can rig up some connection but the voltage is in question? If we are talking xx volts, would the connections be red to positive and black to negative?
::
::In your discussions, there is reference to a filament requiring a different voltage. That would account for the remaining pair of connections. A filament would heat in either direction of electron movement therefore no issue on positive or negative, Yes/NO ?
::
Since your radio is a floor standing unit, you may benefit even more so by a battery eliminating power supply.
Sorry for all the info. Just wanted you to know what the filaments were that I was talking about and what they did. A thorough explanation tends to make the picture clearer.
Good luck,
Thomas
:Thank you very much for the information. You have triggered a few memories of earlier science lessons. It will take me a while to digest this information. You made reference to portable radio. This unit is actually a floor standing unit, the cabinet is 32" high, 26" wide, 12" deep and has a 10" speaker. It was used during an era in a location that did not have electricity. Thank You.
:
:
::Well, here's the scoop:
::
::You do have 7 tubes, and from the looks of it, quite the portable radio. Those 1G4GT tubes should be 1G5GT tubes. This will be hard to explain to you now, since you don't know much about radio yet, but you will understand it better later. The 1G4GT is a triode tube. It has three elements: a cathode, control grid, and a plate. This is a basic amplifier tube. The 1G5GT is a pentode. It has a cathode, control grid, accelerator/screen grid, supressor grid, and a plate. The basically needed elements, the cathode, control grid, and the plate, are connected to the same pins in both tubes. The plus of the 1G5GT is that it has the screen and supressor grids, which make it a stronger amplifying tube. The 1G5GT tubes are used in a special push-pull arrangement for the audio output of your set. Push-pull is a special type of amplification that uses two tubes out of phase with eachother to drive the speaker. Its fidelity is far superior to a single tube driven speaker. Your high end amplifiers in old consol radios and in your modern car/household stereo use push-pull amplification (your stereo is likely transistorized, but the effect is exactly the same). It is rich and enjoyable. When you get the chance, switch the tubes to 1G5GT tubes. For now, though, you will probably be able to get the set running well with the 1G4GT tubes. The set may sound incredibly good with the 1G4GT tubes as well as the 1G5GT tubes. I suspect that it will be a bit louder with the 1G5GT tubes. Do not expect the fidelity of your household stereo from this radio, as it is a portable, and probably is AM only (broadcast and perhaps some short wave bands). Since it is AM only, it is not meant to be super high fidelity anyway, as you don't want to hear the full sound range with AM. This only allows you to hear distortion and static. The bass response of this radio will exceed that of an ordinary portable, though, and the sound won't be as harsh. The treble notes, if allowed through somewhat, will be much truer and not too muffled.
::
::At any rate, I will go down the list of tubes for you and let you know what they are.
::
::2nd black Hammond device is likely the output transformer that feeds the speaker, unless the speaker has its own output transformer.
::1G5GT x 2.......pentode output tubes for push-pull amplification.
::1G6GT ..........twin triode audio preamplifier tube...one triode for each phase of the push-pull output.
::1H5GT ..........triode for audio preamplification prior to the 1G6GT. One of the Hammond transformers is likely the audio interstage transformer between this tube and the 1G6GT. The Hammond transformer splits the audio into two diametrically opposed phases. Another section of the 1H5GT is a diode (two elements...cathode and plate). Serves to rectify the radio frequency signal and detect the audio from this signal.
::1P5GT ..........radio frequency pentode, amplifies prior to the 2nd IF transformer, receives signal from 1st IF transformer (intermediate frequency)....cap on top of tube is the terminal of the control grid of this tube. By placing this terminal away from the others, it is isolated from interferance.
::1A7GT ..........heptode (7 grid) local radio frequency oscillator/radio frequency modulator...combines locally generated frequency (local as in within the radio...by the 1A7 tube) with the incoming radio frequency, and sends it to the 1st IF transformer. This tube is a bit complicated in operation. I will explain its operation some other time if you wish.
::1P5GT ..........RF preamplifier tube....preamplifies incoming signal before sending it to the modulator.
::
::The way a tube works is it has a heated cathode. With AC radios an AC current is used to heat this cathode. Since this AC current would introduce interferance and hum, the cathode, if directly heated--basically a filament, is made very thick, or if indirectly heated, is a filament within a metal tube that serves as the cathode. The filament in the tube heats the tube. The tube, serving as the cathode, is actually what emits electrons in this type of tube. For battery radios, though, the first concern is battery drainage. The former filaments are too thick, and draw too much current--they would drain a battery very quickly. Since a heavy filament is not needed with direct current use, a very thin one can be used. No metal cylinder is needed to isolate the filament from the cathode voltage, so none is used. The filament is very thin and draws very little current. When it is lit, you can barely see it. Typically, with the more modern "octal" (8 pin) tubes, the tube's first number designates its voltage. 1G4GT has a 1.5 volt filament. The filament serves as the cathode in these small battery type tubes.
::
::The second element in a diode tube is the plate. This is a metal cylinder that surrounds the cathode. The cathode, when heated, shakes electrons loose due to the heat. These negative electrons flow towards the plate. If a battery is connected so that its negative side is connected to the cathode and its positive side is connected to the plate, negative electrons will flow from the cathode to the plate. Keep in mind that while this is happening, another battery is lighting the cathode (filament). Between the cathode and the plate is practically nothing--it's a vacuum.
::
::Now, this is a simple diode described above. For amplification purposes, a third element can be placed in a tube, making it a triode. The element is a control grid. It is called a grid because it really looks like a grid. It's basically a specially formed spiral of wire. It looks like a screen in a way. This grid is placed between the cathode and the plate. Something very special can be accomplished with this grid. An extremely small negative charge on the grid can almost stop (and sometimes does stop if the charge is strong enough) the electron flow from cathode to plate. An extremely small positive charge on the grid can excite electron flow to the plate. An extremely small charge of any type on the grid can make a very radical change in electron flow to the plate. By this special characteristic, a tube can be used to amplify a signal. It does not really amplify a signal, but seems to. Basically a tube is used as a controlling device. A very weak signal is applied across the grid and cathode. The signal causes the grid to go ever so slightly more or less negative than the cathode, which radically changes the electron flow from cathode to plate. These radical changes are seen at the plate as a stronger signal. If sent to another tube, the signal may be made stronger still. Typically, in high quality amplifiers, the grid never really goes positive, but is always kept negative. A signal imposed upon it changes this negativity. The reason it must stay negative is because when it is negative, it affects the electrons emitted from the cathode, but the electrons do not collect on the grid. If the grid were allowed to go positive, electrons would flow to the grid instead of the plate, which would throw off the liniarity of the tube's response, and would introduce distortion to the signal.
::
::With a pentode, two more grids are added that are charged with a steady voltage. One grid, after the control grid, is charged positively...almost as positively as the plate. This grid serves to excite electron flow, which makes the tube a stronger amplifier. A third grid is placed after this "screen" grid. It is called a supressor grid. This grid is charged as negatively as the cathode. Since electrons fly at the plate at a much faster rate due to the screen grid, they have a tendency to bounce off the plate and go elsewhere in the tube, which causes interferance. This negatively charged grid keeps the electrons from bouncing off the plate--it repels them back at the plate. You would think that the positively charged screen grid would keep all the electrons for itself, or that the negatively charged supressor grid would stop all electron flow, but as a grid gets farther from the cathode, it has less affect on the electrons. These grids have far less influence on the electrons than the control grid.
::
::As for how the plate sends its information to the next tube or device, a resistor may be connected between it and the positive current source, thereby limiting how much current the plate can see. A strong current of electrons from the cathode would make the plate less positive. A capacitor connected between the plate and the next amplification stage will transfer these changes to the next stage. Another method has the primary coil of a transformer connected in series with the plate and the positive current source. Changes in plate load on this coil induce magnetic fields. A second coil in the transformer senses these magnetic changes, and generates a corresponding current which is fed to the next stage.
::
::At any rate, that said, the filaments I am talking about are those within the tubes. They must be lit by a special low voltage battery called an A battery. The cathode to plate voltage must be supplied by a different high voltage B battery. Usually the B battery for a portable radio like your's is around 67.5 to 90 volts. If the filaments of your radio are wired in parallel, then they would require a 1.5 volt A battery. If they are wired in series, which sometimes is the case, then they would require a 10.5 volt battery. In either case, they must be correctly connected as the A battery voltage does have some affect on how the radio performs, especially if the filaments are wired in series. The A voltage sort-of adds to the B voltage at each filament. The filament of one tube at one end of the string will be much more negative than a filament at the other end of the string. If in parallel, the effect is much less so. This is all thought out when the radio is designed. This difference in voltage throughout the string is used to "bias" each tube. The - wire of the B battery is usually connected somehow to the negative side of the filament string. Usually the red and black wires will be your A battery wires. Red will be the positive wire. Blue and yellow wires are often used for the B battery. Blue would be + and yellow -. This may not be the case in your radio, though. The best way to see what wires are the filament wires is to look at the base of each tube. Pins 2 and 7 are the filament pins. See if the tubes are wired in parallel or in series first. Then, see if one of the tubes has one of the battery wires connected to a filament pin. If more than one wire connects to a filament pin, then one of these wires is A- and one is B-. If parallel wired, the other side of the parallel wiring should go to a switch. If series wired, the other end of the string should go to a switch. The switch may be a two part switch, too, controlling both A and B current. Determine the two sections of the switch with your multi-meter. The wire going to the switch that connects to the filament wiring when the switch is closed will be your A+ wire. The B- wire may be directly connected to part of the filament wiring, as stated above, or it may be connected through a resistor. The B+ wire will likely go to the other part of the switch. When the switch is closed, this will connect to wiring that goes to the audio output transformer. You should get continuity (a resistance measurement of several hundred ohms) between the B+ wire and pin 3 of each of the 1G6GT output tubes. For a B battery, use either a 67.5 or 90 volt battery. When reading a tube basing diagram, the diagram is usually written looking at the underside of the tube socket.
::
::These batteries are available at www.tubesandmore.com, which will supply you with almost all the parts and tubes you will need to get this radio working. They also sell power supplies that allow you to operate this battery radio on AC. Try connecting the A battery either way and see which way works best. Some radios like things one way and some the other. While at the www.tubesandmore.com site, you will also want to purchase David and Betty Johnson's Antique Radio Restoration Guide. This is an excellent book that will help you out with many troubles you may have.
::
::Hopefully you can get this radio working right away by just connecting the batteries. However, condensers (capacitors) like to short out and become leaky. These are the units with MFD ratings on them (microfarad). You will learn about capacitors when you read the above book, or perhaps I can explain them to you some other time. Basically, though, if they have any leakage at all, even in the millions of ohms, they can ruin your set's operation, especially battery sets. They are very sensitive. Be very careful with battery tubes, though. The filaments are extremely easy to burn out.
::
::Sorry for the lengthy explanation which I guess I am famous for, but you need a lot of this information if you are ever to get your radio working right and understand how it works, etc. I also wrote this after working 3rd shift, so I may have been redundant with some things.
::
::Thomas
::
::
:::UPDATE ON DETAILS
:::Correct regarding my limited knowledge about radios.
:::I am looking at the metal housing mounted within the radio, I did not plan to remove it at this time to try and interpret how it was wired underneath.
:::I did gather a bit more information (diagram of major components) and will edit my initial description of chassis.
::::When looking from the back of the radio, and moving from right to left, there is a black device "Hammond 368", a tube J8 - "IG6 GT/G", a "Hammond 334", two J8 - "IG4 GT" tubes (diagram says two IG5 GT), a round metal device (shielded tube - I pulled it out) with wire from top into chassis (diagram says IH5 GT), a square device "#S-104 2nd IF 455 KC" (diagram says IF output 455KC), a round metal device (shielded tube)(diagram says IP5 GT)with wire from top into adjacent square device "#S-103 1st IF 455 KC" (diagram says IF input 455 KC). Then there are 2 more round metal devices (shielded tubes)with top wires going into chassis (diagram says IA7 GT and IP5 GT), 2 unmarked different but identical square devices (diagram says RF Coil 540 KC and OSC Coil 600 KC), 1 unmarked and different square device (diagram says ANT Coil 540 KC)and finally the tuning device.
:::
:::In the wiring bundle the red and black go through two odd plugs in a series manner. I am sure I can rig up some connection but the voltage is in question? If we are talking xx volts, would the connections be red to positive and black to negative?
:::
:::In your discussions, there is reference to a filament requiring a different voltage. That would account for the remaining pair of connections. A filament would heat in either direction of electron movement therefore no issue on positive or negative, Yes/NO ?
:::
Good luck,
Thomas
:As it turned out, I found some local help regarding this radio. An AC power supply has been made to power the three different voltages required. Some tubes and capacitors were replaced and another transformer added to deal with the internal dial lights. The age of the unit from two sources is about 1953. It has a nice sound but has a slight hum. Thanks for you assistance.
Good to hear that your radio is working. As Thomas pointed out the hum could be inherent in the filtering of the power supply. One other thing, if the radio has external antenna and ground connections have you hooked the ground up to a decent ground such as a metal water pipe? I find some of my battery radios have less noise when hooked up to a ground.
Ed.