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Hello, I have been replacing the electrolytic capacitors in my radio, and have gotten down to C142 and C143 listed on the parts list as being on the main chassis.? I can't find them either on the schematic or on the radio.? Does anyone know where they are located?
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Looked this morning on 2 different documents for your caps and could not find them either. I feel your pain.?? Just now I'm trying to resurrect a 101B purchased in working order (hah!).? I successfully rebuilt the rectifier board and am now trying to see if it puts out a signal.? Searching for 'bad looking' components visually did not turn up any bad caps, but I should go through the entire replacement exercise soon.? Overall did you consider it a challenge? I am new to this and wonder if that might be opening a can of worms...
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Hi Pat, I checked the service manual and schematic for C142, C143 but could not locate these parts.? Can you provide that schematic.? If you already have the two capacitors, do they look like this and are they 100uF, 500V?? If so, maybe they are C77, C78.? Did you buy a capacitor kit or just replacing them one by one on your own.??   Dan -- 73, KK7JNR
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Tom, thanks for looking. I'm about ready to chalk it up to an undocumented change.? I found another anomaly while working on the chassis.? There is a large transfomer on the bottom of the unit that has "T-12" printed on it.? My radio has a 10 uF electrolytic going between the leads on this guy.? No mention of that part anywhere that I can find.? Does your FT-101B have this part?? I had an extra 10 uF so went ahead and replaced it.?
As to the challenge, it was certainly a mixed bag. I would not have attempted it without a desoldering tool.? I tested the radio after every board or two.? Most of the boards were straightforward. Getting at the caps on PB-1180 (the one in the metal box) was a challenge; and the caps hiding under, and sharing solder joints with, wires and other components on the chassis took some thought.? ?The next project is the big filter caps? I haven't come across any description how to best change these out.? A project for sure.? Good luck with your radio!
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Dan, thank you for searching.? The caps are 1uF and 100uF.? I also have replacements for the C78 and C77 caps in your picture but that is a separate project.
I did buy a kit and there were extra caps for other units.? These are the only two that are listed in the Ft101B manual that I have not been able to find and replace.
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My version of the service manual
lists T12 on the main board
(. Highly recommended.) .? It is an AF choke, 20mH, 0.5 A.? I have not found it on the schematic, but have not gone over the entire 24 pages looking for it yet.? Too bad the PDF isn't searchable.? Good luck with the continuing labors! TH
On Fri, May 17, 2024 at 1:58?PM Pat Carter, N4IU via <patricia= [email protected]> wrote: Tom, thanks for looking. I'm about ready to chalk it up to an undocumented change.? I found another anomaly while working on the chassis.? There is a large transfomer on the bottom of the unit that has "T-12" printed on it.? My radio has a 10 uF electrolytic going between the leads on this guy.? No mention of that part anywhere that I can find.? Does your FT-101B have this part?? I had an extra 10 uF so went ahead and replaced it.?
As to the challenge, it was certainly a mixed bag. I would not have attempted it without a desoldering tool.? I tested the radio after every board or two.? Most of the boards were straightforward. Getting at the caps on PB-1180 (the one in the metal box) was a challenge; and the caps hiding under, and sharing solder joints with, wires and other components on the chassis took some thought.? ?The next project is the big filter caps? I haven't come across any description how to best change these out.? A project for sure.? Good luck with your radio!
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Tom, not sure my answer posted.? I found T12 on the schematic. I can't find any documentation showing that T12 is supposed to have an electrolytic cap? between its leads.? Wondering if your T-12 has this cap. Thanks.
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Pat,?
I checked on eBay where I bought my recap kit for the FT-101E, but it doesn't show the reference designators.? The E version doesn't have C142, C143 otherwise I would open mind up and see.? Going to be fun.? I see the board change list in the service manual depending on unit serial number will come in handy.? For the chassis I didn't see any change list.??
I'm curious thinking that calibration may be needed after cap replacement.? Are you thinking that too?
Dan
--
73, KK7JNR
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Dan,
I'm not sure what it will need when I'm finished with the recap.? So far when I test, I'm hearing stations where they are spotted, and when I call CQ I'm spotted on frequency.? I haven't taken it above 10W output. It actually has been a fun project.? Do you put your FT101E on the air often?
Pat?
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My ft101b functioned for about 5 minutes when I first bought it. On my first attempt to transmit with it the PA system gave up the ghost almost immediately.? Turned out the rectifier board had several charred components, and the 12 v side of the power supply had a dead power transistor.??
After repairing the problems with the power supply over the course of about a month, it has produced RF only since this morning. There seems to be more wrong with it than the burned circuit board shown in my QRZ? query.? Fortunately this radio was bought as a tool to teach me tube tech operation and troubleshooting. Looks like it will be good for that!
On Fri, May 17, 2024, 7:46 PM Pat Carter, N4IU via <patricia= [email protected]> wrote: Dan,
I'm not sure what it will need when I'm finished with the recap.? So far when I test, I'm hearing stations where they are spotted, and when I call CQ I'm spotted on frequency.? I haven't taken it above 10W output. It actually has been a fun project.? Do you put your FT101E on the air often?
Pat?
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My FT101B originally belonged to my dad.? I put it on the air every month or so, always on CW.? Decided to recap it to learn more about the radio and get better at soldering in tricky situations.? Finished the electrolytics (C78 and C77 were the last to do) today; and the radio appears to have lived through it.? Need to do some checking and maybe adjustment before putting it back on the air.? Hope to hear more about your projects.? Thanks again for checking for the phantom caps.
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Hi Pat,
I bought mine back in the late 70's just getting started with my Novice license.? A career and decades later decided to get back into Ham radio.? For now, thinking about carefully checking it out.? Would hate to damage anything since it's been sitting for years.? Bought an ICOM-7610 but would love to get my first radio back online.??
Dan
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73, KK7JNR
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Dang it.? Me again.
Got my 101B working.? Made QSO's in New Hampshire and Mississippi from VA. Then it stopped modulating USB and LSB.? Still puts out signal on tune and AM. Back to the service manual again.? I'm thinking of dirty relay contacts or a problem with a component in the modulator board.?
Any recommendations?? This thing is providing more learning opportunities that I bargained for.
Tom KO4HNB
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Ello Tom,
I had the same problem and I found that it was the Speech processor.
Check it out, if its not your relay.
Good luck.
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Dang it.? Me again.
Got my 101B working.? Made QSO's in New Hampshire and Mississippi from VA. Then it stopped modulating USB and LSB.? Still puts out signal on tune and AM. Back to the service manual again.? I'm thinking of dirty relay contacts or a problem with a component in
the modulator board.?
Any recommendations?? This thing is providing more learning opportunities that I bargained for.
Tom KO4HNB
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Thanks, Claude.? Another item for the list...
TH
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Cleaned contacts in both relays with card stock and deoxit. Both were visibly dirty. Fired radio up and receive is OK, but I could not get any idle current in Tune mode. I checked rectifier board supply lines and saw:
+748v (vs +600v theory)
-180.7v vs -100v theory
+182.3v vs +150 v
11.5v AC is 10.5v AC
+14.2v vs +13.5v
Yikes!
No sign of damage anywhere. Re-seated relays, but no change. Checking tube now.? The PA tubes are different brands, so I'm guessing all 3 will be replaced before aligning the thing. But right now the big thing seems to be weirdness with power.
I feel snake-bit. Suggestions, anyone?
73,
Tom AI4TH [was KO4HNB]
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Check to see if the wire wound .6ohm resistor, located on the bottom of the power tube sockets, has been blown open from excessive current.?
if yes, you might have bad power tubes too.?
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I ran into similar discrepancies when I resurrected my 101E after nearly 30 years in storage. The comments I got back from reputable service people was that tables were "generally accurate" but not to be considered to be dead on. As long as they were steady and nothing seemed to be "suffering" they were OK.
Check to see if the wire wound .6ohm resistor, located on the bottom of the power tube sockets, has been blown open from excessive current.?
if yes, you might have bad power tubes too.?
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The wire wound resistors were OK. I cleaned the flying lead contacts and pins on tubes and tested the drive tube, which was OK. No tester was available for the PA tubes. Re-installed tubes and everything worked.
Completed the Rx and Tx alignment process and started 'on air' testing. Power out is low, (20 to 80 watts)? and Rx and TX frequencies do not match. (People have said 'You are off-frequency' every time I've made contacts on this radio.)? I have seen videos on fixing the latter issue and will try to locate matching tunes to get power level up.?
This thing is slowly rejoining the land of the living, but I have to say that using it makes me appreciate my TS590sg!
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Sorry- my reply never went through.? Yes, I have the cap on the audio choke.
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Tom ai4th
Claude VE2YI
Bruce Collins
Ron, N1BHE