This 13-transistor radio has weak volume across all three bands. I have to turn the volume up all the way to hear any reception; even then, it sounds like I have to turn it up more. There is currently no hum and the reception is good on all three bands.

Would replacing the main filter capacitor help improve volume? (There is a small schematic drawing with the radio. What else could I check?) Thank you in advance for your help.

Mark

Transistor radios usually have electrolytic coupling caps. These will dry out over time. You could try bridging each in your radio looking for improved volume.

Filter caps could be a problem but usually cause hum. Check the DC voltage from your power supply. If it's ok filter caps will be also.

Norm

: This 13-transistor radio has weak volume across all three bands. I have to turn the volume up all the way to hear any reception; even then, it sounds like I have to turn it up more. There is currently no hum and the reception is good on all three bands.

: Would replacing the main filter capacitor help improve volume? (There is a small schematic drawing with the radio. What else could I check?) Thank you in advance for your help.

Hi,

If the caps turn up nothing, try noise injection with a screw driver. Start from the first audio stage, and work back. At some point there will be little difference across one stage, and that is the transistor to check for excessive leakage.

Any of them can be the culprit, but if you take even a VOM across the leads with the transistor out of the circuit, You will find that a good transistor gives you readings to indicate diode junctions across those two leads, so one direction will have a relatively low resistance reading, while reversing the leads gives a high resistance reading (at least a difference of 10 to 1 as a minimum for most applications). You may also find that one has the same reading across the Emitter and Collector regardless of test lead polarity- this will be a bad transistor.

It may be easier to visualize testing a transistor by looking at it as 2 diodes tied together in series, with the base lead being the point where the two diodes are tied together.

Usually the first to fail are the drivers for the output, and then the output stage transistors.

: Mark

: Transistor radios usually have electrolytic coupling caps. These will dry out over time. You could try bridging each in your radio looking for improved volume.

: Filter caps could be a problem but usually cause hum. Check the DC voltage from your power supply. If it's ok filter caps will be also.

: Norm

:
: : This 13-transistor radio has weak volume across all three bands. I have to turn the volume up all the way to hear any reception; even then, it sounds like I have to turn it up more. There is currently no hum and the reception is good on all three bands.

: : Would replacing the main filter capacitor help improve volume? (There is a small schematic drawing with the radio. What else could I check?) Thank you in advance for your help.

Hello All,

John, your description of a transistor being two diodes connected together is interesting. So the base or connection point, is where electron flow can be regulated? It was always easier for me to understand how a thin wire (control grid) could regulate electron flow between a cathode and a plate. Semiconductor theory was a little harder to understand with its' "electron holes" and all. Guess that's why I ended up being a chemical engineer instead of an electrical engineer :-)

: Hi,

: If the caps turn up nothing, try noise injection with a screw driver. Start from the first audio stage, and work back. At some point there will be little difference across one stage, and that is the transistor to check for excessive leakage.

: Any of them can be the culprit, but if you take even a VOM across the leads with the transistor out of the circuit, You will find that a good transistor gives you readings to indicate diode junctions across those two leads, so one direction will have a relatively low resistance reading, while reversing the leads gives a high resistance reading (at least a difference of 10 to 1 as a minimum for most applications). You may also find that one has the same reading across the Emitter and Collector regardless of test lead polarity- this will be a bad transistor.

: It may be easier to visualize testing a transistor by looking at it as 2 diodes tied together in series, with the base lead being the point where the two diodes are tied together.

: Usually the first to fail are the drivers for the output, and then the output stage transistors.

:
: : Mark

: : Transistor radios usually have electrolytic coupling caps. These will dry out over time. You could try bridging each in your radio looking for improved volume.

: : Filter caps could be a problem but usually cause hum. Check the DC voltage from your power supply. If it's ok filter caps will be also.

: : Norm

: :
: : : This 13-transistor radio has weak volume across all three bands. I have to turn the volume up all the way to hear any reception; even then, it sounds like I have to turn it up more. There is currently no hum and the reception is good on all three bands.

: : : Would replacing the main filter capacitor help improve volume? (There is a small schematic drawing with the radio. What else could I check?) Thank you in advance for your help.

Hi,
The "two diode" analogy is something that GE used in it's 1964 (and probably others) for visualization purposes. Performancewise, transistors are compared to pentodes, but the actual operation of a transistor is much like that of a triode. Base would correspond to the grid, and depending on the type of transistor, In an NPN transistor: Collector would correspond to the plate, and the Emitter would correspond to the Cathode. With a PNP type, the base has the same function, but the current flow between Emitter and Collector is opposite to that of the NPN.

A chemical engineer? Oh, so you must be the guy responsible for that confection sold as "Peeps"....

: Hello All,

: John, your description of a transistor being two diodes connected together is interesting. So the base or connection point, is where electron flow can be regulated? It was always easier for me to understand how a thin wire (control grid) could regulate electron flow between a cathode and a plate. Semiconductor theory was a little harder to understand with its' "electron holes" and all. Guess that's why I ended up being a chemical engineer instead of an electrical engineer :-)

: : Hi,

: : If the caps turn up nothing, try noise injection with a screw driver. Start from the first audio stage, and work back. At some point there will be little difference across one stage, and that is the transistor to check for excessive leakage.

: : Any of them can be the culprit, but if you take even a VOM across the leads with the transistor out of the circuit, You will find that a good transistor gives you readings to indicate diode junctions across those two leads, so one direction will have a relatively low resistance reading, while reversing the leads gives a high resistance reading (at least a difference of 10 to 1 as a minimum for most applications). You may also find that one has the same reading across the Emitter and Collector regardless of test lead polarity- this will be a bad transistor.

: : It may be easier to visualize testing a transistor by looking at it as 2 diodes tied together in series, with the base lead being the point where the two diodes are tied together.

: : Usually the first to fail are the drivers for the output, and then the output stage transistors.

:
: :
: : : Mark

: : : Transistor radios usually have electrolytic coupling caps. These will dry out over time. You could try bridging each in your radio looking for improved volume.

: : : Filter caps could be a problem but usually cause hum. Check the DC voltage from your power supply. If it's ok filter caps will be also.

: : : Norm

: : :
: : : : This 13-transistor radio has weak volume across all three bands. I have to turn the volume up all the way to hear any reception; even then, it sounds like I have to turn it up more. There is currently no hum and the reception is good on all three bands.

: : : : Would replacing the main filter capacitor help improve volume? (There is a small schematic drawing with the radio. What else could I check?) Thank you in advance for your help.