Re: QMX+ No transmit or receive
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I made some checks of the following as instructed:
IC408 pin# only has 2.5v.? (idle receive) IC402 pin#9 is 0v,? IC403 pin#7 is? 0v, pin#9 is 0v C402 pin#1 0v and pin#3 0v.?
I may have a problem here. I confirmed already this morning that the different LPF fets were turning on. I may have to review my IC spec sheets again but i am pretty sure i selected all the right pins. When i get more time tonight or tomorrow, i am going to confirm. Thanks.
73s? VY2KW
sorry, line 1) has a few words that were supposed to?go to line 2).
Thank you Ludwig!! And a happy new year to you and your family. I actually just saw this now. Lol, I got some time this morning. I tried again to track down a problem in the receive path. This is what i have found so far this morning:
1) I have continuity from C526 to the anode of each 1N4007 diodes closest to the rear of the radio and from the cathode of?each.?
2) I have good continuity across each LPF to my capacitors (3) in each filter with isolation from the other half to ground for each.
3) I have good continuity from the C509 capacitor to the anode of each 1N4007 diode facing toward front of radio.?
4) When I select different bands, I?can see the source of each FET in each LPF turn on and then off when selecting all the different bands from 160 -? 6m.?
5) I have continuity from C509 to the Drain of Q508 and good continuity from the source?of Q508 to the pin 5? of IC408.
I am definitely?going to check out those voltages you have graciously supplied for me. I greatly appreciate it?because for all I know, you may have taken your radio all apart and spent an hour or two getting me this valuable info. It is great to have top notch help like yours!!!!
73s VY2KW
Joel, sorry for coming back so late. Yesterday a strong cold hit me and gave me my first wish for the new year.
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Your next steps could be
- check some voltages at the output of IC408. One of the pins B1...B8 should have 5 V and all the other less voltage. Which Bx depends on the selected BPF.
- check voltage at pin 9 of IC402 and voltage at pin 9 and pin 7 of IC403. All should have 2.5 V.
- check voltage at pin Y0 ... Y3 of IC402. One of the pins should have 2.5 V and all the other less voltage. Which Yx depends on the selected BPF.
Probe at solder pads connected to these pins, e.g. solder pad to L401, L403, ..., T401 and so on.
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Wish you HNY.
73 Ludwig
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