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Re: New to me FT-101B
Are you saying that when in USB or LSB, the minimum idle current is 160ma when you set the bias pot for minimum idle current and you have no mic connected? Etc.?
Yes, that sounds like massive under bias condition which can happen from numerous problems, such as:
one or both the power tubes are bad, the bias supply circuit is bad, the coupling capacitor from the output of the driver tube to the grids of the power tubes is bad or a component at the grids of the power tubes is shorted to ground or burned open, etc.?
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I’m assuming you know the high voltage rules and know what you are doing.
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So the first thing I would do is pull out the chassis from the case and remove the power tubes. ?Flip it over and from the bottom, visually inspect the power and driver tube circuitry for damaged parts.
Then when able to safely test the chassis, measure the actual negative bias voltage delivered to the power tube sockets when in SSB receive and then SSB transmit. The difference in negative bias voltage should be obvious between Rcv and Trx. Receive bias voltage will be very deeply negative. ?
If it is there, replace the original coupling capacitor from the 12BY7 to the power tubes before going much further. It is the source of many of these power tubes issues. So is the small 1/2 watt, grid stopper resistor, which is connected to the coupling capacitor …. It is connected to the grids of the power tube sockets. ? Also, consider joining the “Keeping The FT-101 Alive!” Facebook page for more help. This group is only for these radios, none other. ?
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New to me FT-101B
Hello to all here. I'm Butch - KA?WWT and have recently purchased an FT-101B (SN: SC119507) along with the YC-601B Digital Display.?
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The rig has been 'on the shelf' for a great deal of time but was well taken care of before that and during that time. It has the original tubes in it and still has the glue/paint/whatever on all of the screws in the boards. I don't believe anything was ever done to this rig after the initial purchase from the looks of it.?
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Fast forward to now, I attempted to do an initial tune up on her and I am not able to get the idle current reading down to the 60 milliamps according to the initial tune. And that is with the Bias adjust VR2 turned all the way to minimum. Best I can get is around 150ma. So, that is where I have stopped and am now pouring over any and all documentation I can find. Thing is, I am not finding what is probably right in front of me.
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And now I am here reaching out for some guidance. Is this a driver tube problem? An adjustment on a trimmer cap that I am not seeing?
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My intention is to get this rig back on the air and will certainly make it a project to do just that. I have not cleaned or reseated anything as of yet, I have some contact cleaner coming and it should be here this week.
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From my list of things to do at this point:
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0. Inspect as much of the rig I can see, upper and lower for any cracked caps or any other potential damage. (I have not seen any of that topside at all.)?
1. Remove and inspect all boards, clean contacts and connectors.
2. Clean all switches with cleaner.
3. Clean wafer switches with either erasers or contact cleaner (incrementally and not a mad wash of everything).
4. Change all the electrolytic caps.
5. Change out C13 and C131 with newer better caps.
6. Put it all back together and smoke test it.?
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All this will take me a bit of time but I intend to put in the work. I have the service manual as well as the instruction manual and I am not afraid to use them. Yep, I am well versed (albeit very rusty working on electronics), in this sort of stuff but it will be a relearning experience for me. I am happy to see a schematic that I can easily recognize parts again. Right now, all I have are a couple of volt meters. I will have to borrow an O'scope but I know where one is.?
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My ask of the community here is, can you recommend some additional steps I can do now or during that I may have not considered initially??
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The receive on the rig is good on some bands and could be better. on others. The preselector is scratchy when I move it through its ranges. Is that something I can fix, if so, how??
All the knobs need some cleaner of some sort or another. They are all scratchy to some degree. I expect the contact cleaner and exercising them to work those bugs out.?
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Here are a couple of pictures of the rig. I posted on the FoxTango site as well a few days back.?
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I greatly appreciate any help or guidance from anyone here and thank you in advance.?
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Regards,?
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Butch - KA?WWT
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Re: Very Sticky Original Grease in Drive Reduction Vernier Assemblies
I’ve never had much luck in restoring those worn Jackson Ball Drive units.? easy to disassemble and reassemble but still choppy even lubed or dry.? Try using a good lens to see if there are tiny divets in channel ground into the shaft. That is the cause of most bad units.? |
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Re: FT-101EE : C13 80pF Moulded Mica Capacitor
Claudio I replace it (c13) by ceramic capacitor without problems. att Emerson PP6EW Em sex., 13 de dez. de 2024 às 01:29, Claudio Bio via <claudiobio2012=[email protected]> escreveu:
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Re: FT-101EE - R40 Metallic Film resistor
Claudio these resistor you can find at aliexpress.? Another idea is replace by two x 3k // or 3 x 4k7 // (parelal) resistor. att Emerson PP6EW Em sex., 13 de dez. de 2024 às 01:29, Claudio Bio via <claudiobio2012=[email protected]> escreveu:
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FT-101EE - R40 Metallic Film resistor
Hello again
This is Claudio Bio - OA4BMG from Lima Perú During a inspection on my 101 I found R40 burned.
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R40 is locate on Main Chassis, it is 1.5k ohms 5w 10% Metallic Film resistor.
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If I can’t find it as Metallic Film resistor; what other type of resistor can be used without any chance of damage my radio and also decrease performance.
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I would really appreciate your comments based on your experience.
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73,
Claudio
OA4BMG
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FT-101EE : C13 80pF Moulded Mica Capacitor
Hello?
This is Claudio Bio - OA4BMG from Lima Perú?
Am performing a recap to my 101.
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For safety am going to replace C13 locate on Main Chassis, it is 80 pF Moulded Mica capacitor.
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If I can’t find it as Moulded Mica what other type can fit without any further problem?
Maybe a normal Mica?
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I would really appreciate your comments based on your experience.
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73,
Claudio?
OA4BMG
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Bruce Collins
Butchie_T - KA?WWT
Tom - AJ8X
Tom ai4th