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Op-amp problems?
#calibration
#opamp
#20m
Hi Ron many thanks for the helpful and welcome info and advice. I'd been working on the assumption that there's a problem somewhere around IC6 and IC7 stages/ circuitry on account of not being able to
Hi Ron many thanks for the helpful and welcome info and advice. I'd been working on the assumption that there's a problem somewhere around IC6 and IC7 stages/ circuitry on account of not being able to
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By
Rod Smith
· #61017
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QCX+ mini - No tone while aligning - signal dying after IC10 - can not align I-Q
#20m
#alignment
#qcxmini
Hi I just wanted to post the results of my qcx-mini. I posted earlier in this thread that I had the same symptons as Josh and had recorded the voltages on all pins from IC6-IC10. The voltages on IC10
Hi I just wanted to post the results of my qcx-mini. I posted earlier in this thread that I had the same symptons as Josh and had recorded the voltages on all pins from IC6-IC10. The voltages on IC10
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By
chk.aky@...
· #61015
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Op-amp problems?
#calibration
#opamp
#20m
Hi Rod. If you’re getting that good of a signal level on the BPF adjustment then you have audio through IC5,6&7. It’s disappearing somewhere through IC8,9 or 10 for some reason. Since you don’t have a
Hi Rod. If you’re getting that good of a signal level on the BPF adjustment then you have audio through IC5,6&7. It’s disappearing somewhere through IC8,9 or 10 for some reason. Since you don’t have a
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By
Ronald Taylor
· #60999
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Op-amp problems?
#calibration
#opamp
#20m
Hi I'm another with this opportunity (I just hope it isn't insurmountable!). All voltages seem ok, I've checked T1, any number of soldered connections - no joy (and no dual sweep 'scope). The BPF peak
Hi I'm another with this opportunity (I just hope it isn't insurmountable!). All voltages seem ok, I've checked T1, any number of soldered connections - no joy (and no dual sweep 'scope). The BPF peak
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By
Rod Smith
· #60989
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Op-amp problems?
#calibration
#opamp
#20m
I'm having the same problem and all the voltages check out. I'm going to try some other trouble shooting steps this weekend and see if I can't get it going.
I'm having the same problem and all the voltages check out. I'm going to try some other trouble shooting steps this weekend and see if I can't get it going.
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By
Daniel Conklin
· #60978
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Op-amp problems?
#calibration
#opamp
#20m
I am experiencing similar issues: everything works and sounds like a radio, but it is mostly deaf, and there is no effect from the alignment pots. Established continuity and correct component values t
I am experiencing similar issues: everything works and sounds like a radio, but it is mostly deaf, and there is no effect from the alignment pots. Established continuity and correct component values t
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By
Steve Mook
· #60928
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Can i substitute
#20m
#troubleshooting
#help
Where were you looking? it's available at this link for $3.00 ea. https://www.ebay.com/itm/3B3253-High-Bandwidth-4-1-Mux-DeMu-IC-16pin-TSSOP-QTY-1/330550179839?hash=item4cf65377ff:g:168AAOxyvSVREogY
Where were you looking? it's available at this link for $3.00 ea. https://www.ebay.com/itm/3B3253-High-Bandwidth-4-1-Mux-DeMu-IC-16pin-TSSOP-QTY-1/330550179839?hash=item4cf65377ff:g:168AAOxyvSVREogY
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By
VE3VXO
· #60770
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Can i substitute
#20m
#troubleshooting
#help
Yes I have used that ebay store to purchase small quantities before. Had no problems with delivery or anything, but that was more than a year ago. Perhaps they are temporarily out of stock?
Yes I have used that ebay store to purchase small quantities before. Had no problems with delivery or anything, but that was more than a year ago. Perhaps they are temporarily out of stock?
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By
VE3VXO
· #60769
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Can i substitute
#20m
#troubleshooting
#help
There is an "IBS electronics" that seems to sell them but it also looks like a dead end. Probably you need to order a full reel or more.
There is an "IBS electronics" that seems to sell them but it also looks like a dead end. Probably you need to order a full reel or more.
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By
Fred Spinner
· #60764
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Can i substitute
#20m
#troubleshooting
#help
Interesting specs. However, the only sales agency I could find was an Ebay store listed on Potato's website, but comes up as "0 results" when searched for on Ebay. 73 Jim W4JED
Interesting specs. However, the only sales agency I could find was an Ebay store listed on Potato's website, but comes up as "0 results" when searched for on Ebay. 73 Jim W4JED
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By
James Daldry W4JED
· #60762
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Can i substitute
#20m
#troubleshooting
#help
Yes you would have to tack some diodes in the supply line to the potato chip but it might improve the performance of the QCX at the upper end. Potato semi make a bunch of nice real high speed variants
Yes you would have to tack some diodes in the supply line to the potato chip but it might improve the performance of the QCX at the upper end. Potato semi make a bunch of nice real high speed variants
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By
VE3VXO
· #60751
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Can i substitute
#20m
#troubleshooting
#help
Thanks, Fred. Ok on the two different TI part numbers for 5v vs. 3.3v. I had to look up the Potato Chip company as I was curious who they were. They are ‘fabless’ meaning they have to contract other s
Thanks, Fred. Ok on the two different TI part numbers for 5v vs. 3.3v. I had to look up the Potato Chip company as I was curious who they were. They are ‘fabless’ meaning they have to contract other s
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By
Gregg Myers
· #60750
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Can i substitute
#20m
#troubleshooting
#help
For the TI part, you would want the SN74CBT3253CD(R) for the SOIC 5V (7V max) version not the LV version. Mouser qty 1: $0.70 (US) QS3253S1G8: $0.55 Digi-Key qty 1: $0.70 QS3253S1G8: $0.68 Those are t
For the TI part, you would want the SN74CBT3253CD(R) for the SOIC 5V (7V max) version not the LV version. Mouser qty 1: $0.70 (US) QS3253S1G8: $0.55 Digi-Key qty 1: $0.70 QS3253S1G8: $0.68 Those are t
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By
Fred Spinner
· #60749
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Can i substitute
#20m
#troubleshooting
#help
I see from the PO3B3253A and 74CBTLV3253D datasheets these are Vcc 3.3v devices and the current schematic has IC4 at Vcc +5v. So they wouldn't be drop in replacements unless Vcc is changed on IC4 or I
I see from the PO3B3253A and 74CBTLV3253D datasheets these are Vcc 3.3v devices and the current schematic has IC4 at Vcc +5v. So they wouldn't be drop in replacements unless Vcc is changed on IC4 or I
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By
Gregg Myers
· #60739
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Can i substitute
#20m
#troubleshooting
#help
Another option is the one made by potato semi. Maybe a better choice if you are building for the higher frequency bands http://www.potatosemi.com/potatosemiweb/datasheet/PO3B3253A.pdf
Another option is the one made by potato semi. Maybe a better choice if you are building for the higher frequency bands http://www.potatosemi.com/potatosemiweb/datasheet/PO3B3253A.pdf
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By
VE3VXO
· #60734
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Can i substitute
#20m
#troubleshooting
#help
Note that all QRP Labs products (incl QCX+ and QVC-mini) will use the SOIC16 TI part going forward since even our substantial stock of FST parts is gone. 73 Hans G0UPL http://qrp-labs.com
Note that all QRP Labs products (incl QCX+ and QVC-mini) will use the SOIC16 TI part going forward since even our substantial stock of FST parts is gone. 73 Hans G0UPL http://qrp-labs.com
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By
Hans Summers
· #60725
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Can i substitute
#20m
#troubleshooting
#help
When I eventually get a Mouser or Digi-Key order in I plan on buying a few QS3253S1G8 parts because they are the closest electrically and mechanically to the current discontinued FST3253MX SOIC parts.
When I eventually get a Mouser or Digi-Key order in I plan on buying a few QS3253S1G8 parts because they are the closest electrically and mechanically to the current discontinued FST3253MX SOIC parts.
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By
Fred Spinner
· #60710
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Can i substitute
#20m
#troubleshooting
#help
Sorry Vince Not even close. The 138 is a single 3 to 8 decoder. The 3253 is a dual 1 to 4 decoder. You replace a 3253 with another 3253. 73 Jim W4JED
Sorry Vince Not even close. The 138 is a single 3 to 8 decoder. The 3253 is a dual 1 to 4 decoder. You replace a 3253 with another 3253. 73 Jim W4JED
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By
James Daldry W4JED
· #60708
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Can i substitute
#20m
#troubleshooting
#help
Vince, the 74HC138 is a 3-to-8 Line Decoder/Demultiplexer. The FST 3253 is a 4:1 multiplexer / demultiplexer. So I guess the answer is NO. It is not a good substitute. Ron
Vince, the 74HC138 is a 3-to-8 Line Decoder/Demultiplexer. The FST 3253 is a 4:1 multiplexer / demultiplexer. So I guess the answer is NO. It is not a good substitute. Ron
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By
Ronald Taylor
· #60706
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Can i substitute
#20m
#troubleshooting
#help
Quick question can i substitute a CD74HC138 for the FST 3253?? asking for a friend who has the 74HC138.. Vince
Quick question can i substitute a CD74HC138 for the FST 3253?? asking for a friend who has the 74HC138.. Vince
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By
Vince Loschiavo
· #60703
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