It's hard to tell without a schematic. Be sure the power supply is filtered & decoupled. You shouldn't run a 6C4 and 2 sections on the 6AU8 off the same B+ voltage without decoupling.
Be sure grid bias is reasonable. The 6AU8 pentode section must have negative grid voltage. How did you decide to use a 6C4 for the audio output?
Norm
: I have a regen project that is giving me fits. I built a 3 tube set, rf pre-amp and audio amp are 6C4. The detector and first amp are a 6AU8. I have three coils with a gang switch to cover 160, 75/80, and 40 meters. It worked really well, at first. Then the sensitivity and clarity went to pot. Regeneration control is mushy and critical. The voices are extremely distorted. SSB is a memory. Volume is way down. I was so disgusted that is took it apart and rebuilt it with new metalized caps and double checked all the resistors using 1 watt ones throughout. I checked the tubes, they test OK. I am now thinking the coils are at fault or the switching system is causing me problems. Some coils work better than others. Tickler spacing is adjustable so, that aspect is covered. I did run the wires for the coils and ticklers tight against the chasis. Does any of this sound familiar to anyone.
The Schematic is from the book, "How to build Your first regenerative receiver". It specifies The 6c4 for both in on of their example schematics. The powersupply is a good one. It has 250V unregulated and 150V regulated B+. The receiver uses both for different sections.
I will check the grid bias.
What do you think about running the wires from the coils to the switch right up against the chasis?? The meatalzed caps?
Thanks,
Scot
: Scott
: It's hard to tell without a schematic. Be sure the power supply is filtered & decoupled. You shouldn't run a 6C4 and 2 sections on the 6AU8 off the same B+ voltage without decoupling.
: Be sure grid bias is reasonable. The 6AU8 pentode section must have negative grid voltage. How did you decide to use a 6C4 for the audio output?
: Norm
: : I have a regen project that is giving me fits. I built a 3 tube set, rf pre-amp and audio amp are 6C4. The detector and first amp are a 6AU8. I have three coils with a gang switch to cover 160, 75/80, and 40 meters. It worked really well, at first. Then the sensitivity and clarity went to pot. Regeneration control is mushy and critical. The voices are extremely distorted. SSB is a memory. Volume is way down. I was so disgusted that is took it apart and rebuilt it with new metalized caps and double checked all the resistors using 1 watt ones throughout. I checked the tubes, they test OK. I am now thinking the coils are at fault or the switching system is causing me problems. Some coils work better than others. Tickler spacing is adjustable so, that aspect is covered. I did run the wires for the coils and ticklers tight against the chasis. Does any of this sound familiar to anyone.
Running coils wires along the chassis will add a little capacity. This would tend to reduce the high RF end of the band. Meatalized caps are fine.
You mentioned at first the radio was ok. Look for something that changed. Power supply and grid bias are two things that often cause this problem. If you have a scope, check the audio waveform to be sure it's not clipped.
Norm
: Hi Norm,
: The Schematic is from the book, "How to build Your first regenerative receiver". It specifies The 6c4 for both in on of their example schematics. The powersupply is a good one. It has 250V unregulated and 150V regulated B+. The receiver uses both for different sections.
: I will check the grid bias.
: What do you think about running the wires from the coils to the switch right up against the chasis?? The meatalzed caps?
: Thanks,
: Scot
:
:
: : Scott
: : It's hard to tell without a schematic. Be sure the power supply is filtered & decoupled. You shouldn't run a 6C4 and 2 sections on the 6AU8 off the same B+ voltage without decoupling.
: : Be sure grid bias is reasonable. The 6AU8 pentode section must have negative grid voltage. How did you decide to use a 6C4 for the audio output?
: : Norm
: : : I have a regen project that is giving me fits. I built a 3 tube set, rf pre-amp and audio amp are 6C4. The detector and first amp are a 6AU8. I have three coils with a gang switch to cover 160, 75/80, and 40 meters. It worked really well, at first. Then the sensitivity and clarity went to pot. Regeneration control is mushy and critical. The voices are extremely distorted. SSB is a memory. Volume is way down. I was so disgusted that is took it apart and rebuilt it with new metalized caps and double checked all the resistors using 1 watt ones throughout. I checked the tubes, they test OK. I am now thinking the coils are at fault or the switching system is causing me problems. Some coils work better than others. Tickler spacing is adjustable so, that aspect is covered. I did run the wires for the coils and ticklers tight against the chasis. Does any of this sound familiar to anyone.
The wire under the chasis troubles me. I did make that change. Seems like it worked OK after. I have fiddled with it so much I can't remember now. I will change it back. I had run the coil wires above the chasis through strips of lucite a la telegraph poles. I will change it back. The power supply is a dandy. Much better than one I built from a kit using integegrated parts. It is a regulated tube rectified/ regulated supply with two B+ and 6V AC. I used a new AES transformer. It is boxed up real pretty and is much cleaner, sound wise, than the kit supply. With my other regens it works great. Maybe the new set is pulling too much power?? Only three tubes though. I guess I could add another resistor and split the 250 B+. The set does sputter and "Brappp" if put to much power to the tickler and turn the volume all the way up. I can stop that by increasing the size of the resistor in front of the regen pot.
Regarding a scope. Don't have one but, I will look for one at the next hamfest. I had a junkie one and stripped it for parts. I should get one and probably one of those signal detector devices. Right now all I have is a combo meter/ cap meter.
Scot
: Hi Scot
: Running coils wires along the chassis will add a little capacity. This would tend to reduce the high RF end of the band. Meatalized caps are fine.
: You mentioned at first the radio was ok. Look for something that changed. Power supply and grid bias are two things that often cause this problem. If you have a scope, check the audio waveform to be sure it's not clipped.
: Norm
: : Hi Norm,
: : The Schematic is from the book, "How to build Your first regenerative receiver". It specifies The 6c4 for both in on of their example schematics. The powersupply is a good one. It has 250V unregulated and 150V regulated B+. The receiver uses both for different sections.
: : I will check the grid bias.
: : What do you think about running the wires from the coils to the switch right up against the chasis?? The meatalzed caps?
: : Thanks,
: : Scot
: :
:
: :
: : : Scott
: : : It's hard to tell without a schematic. Be sure the power supply is filtered & decoupled. You shouldn't run a 6C4 and 2 sections on the 6AU8 off the same B+ voltage without decoupling.
: : : Be sure grid bias is reasonable. The 6AU8 pentode section must have negative grid voltage. How did you decide to use a 6C4 for the audio output?
: : : Norm
: : : : I have a regen project that is giving me fits. I built a 3 tube set, rf pre-amp and audio amp are 6C4. The detector and first amp are a 6AU8. I have three coils with a gang switch to cover 160, 75/80, and 40 meters. It worked really well, at first. Then the sensitivity and clarity went to pot. Regeneration control is mushy and critical. The voices are extremely distorted. SSB is a memory. Volume is way down. I was so disgusted that is took it apart and rebuilt it with new metalized caps and double checked all the resistors using 1 watt ones throughout. I checked the tubes, they test OK. I am now thinking the coils are at fault or the switching system is causing me problems. Some coils work better than others. Tickler spacing is adjustable so, that aspect is covered. I did run the wires for the coils and ticklers tight against the chasis. Does any of this sound familiar to anyone.