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TR7 recommission stalls.

Mike Davidsohn G3ZCC All Messages By This Member #81867 Good evening everyone. The Tr7 has stopped working. I have traced it to the PBT/REFERENCE board. Have it fitted to extenders, all oscillators working fine except the 8.050, which does not appear to be working at all. I think the manual has a typo on the number of the coils.1101? I have also tried testing this by draping both the frequency counter and a gc rx listening on the frequency.. Manual not too clear (just my luck). Anyone have any ideas? Thanks in advance. Mike G3ZCC ?
Craig W8CS All Messages By This Member #81870 Hi Mike- ? I just spent the last two weeks inside the PBT board before finding my issue. Per the alignment procedure, do you: ? Have 40MHz on pin 19?? Have 53.695 MHz on pin 17? Have 5.645MHz on pin 40? I do have a supposedly working PBT board arriving here next week that I bought from eBay, which I no longer need. Consider that for worst case.? -- Craig/W8CS Greenville, SC
Mike Davidsohn G3ZCC All Messages By This Member #81871 Hi Craig? Sounds,like a plan. Going to check those pin numbers again. Will let you know tommorrow, what thevpins have on them. Seem to remember 19/21 were 40 mhz. Kind regards? Mike G3ZCC ?
Jim Shorney All Messages By This Member #81878 The manual is very clear. The explanation of how that stage works begins in the last paragraph on page 2-50. It is an autodyne mixer. It does appear that the two output side inductors are mislabeled but that is easy enough to figure out from the photo. You should not be tweaking coils to fix a hard failure. Your main suspects are Molexia, failed Q1008, bad crystal, Q1004 not switching as it should, insufficient 13.695 injection from Q1005, and solder joint(s) (not necessarily in that order). You will not be measuring 8.050 directly. As mentioned by Craig you should see the 5.645 (nominal) BFO signal on pin 40 in any mode except AM RX. If you see 5.645 on the drain of Q1008 but not on pin 40 you have a problem in the BFO steering matrix CR1006 through CR1011. On Sat, 11 Jan 2025 10:06:50 -0800 "Mike Davidsohn G3ZCC via groups.io" <mike@...> wrote: Good evening everyone. The Tr7 has stopped working. I have traced it to the PBT/REFERENCE board. Have it fitted to extenders, all oscillators working fine except the 8.050, which does not appear to be working at all. I think the manual has a typo on the number of the coils.1101 I have also tried testing this by draping both the frequency counter and a gc rx listening on the frequency.. Manual not too clear (just my luck). Anyone have any ideas? Thanks in advance. Mike G3ZCC -- 73 -Jim NU0C
Mike Davidsohn G3ZCC All Messages By This Member #81888 Thanks Jim. Mike? G3ZCC?
Mike Davidsohn G3ZCC All Messages By This Member #81890 Dear Jim and Craig 40 mhz on p19 53.695 on p17 Where is p40? I can hear 5.645 on an adjacent rx and correctly not when the Tr7 is in AM Mode. Sorry but I can't find the sheet I had with the pin numbers on Kind Regards Mike G3ZCC
Jim Shorney All Messages By This Member #81893 Look here: /g/DRAKE-RADIO/files/TR-7/TR-7%20Parent%20Board%20Pin%20Numbering.pdf Pin 40 is the right-most pin as you are looking from the front of the radio, next to the PA deck. It is a short trace connecting the PBT/REF and 2nd IF boards. On Sun, 12 Jan 2025 08:14:55 -0800 "Mike Davidsohn G3ZCC via groups.io" <mike@...> wrote: Dear Jim and Craig 40 mhz on p19 53.695 on p17 Where is p40? I can hear 5.645 on an adjacent rx and correctly not when the Tr7 is in AM Mode. Sorry but I can't find the sheet I had with the pin numbers on Kind Regards Mike G3ZCC -- 73 -Jim NU0C
Mike Davidsohn G3ZCC All Messages By This Member #81894 Thank you Jim Will check it. Kind Regards? Mike G3ZCC?
Mike Davidsohn G3ZCC All Messages By This Member #81913 Hi guys Signals on each of the neccessary board pins present. Going to refit the extender cards and see what's missing on the board. Mike G3ZCC
Craig W8CS All Messages By This Member #81914 On your original post you said the TR7 "Stopped Working."? ? What exactly "stopped working?"? ? Have you checked the supply voltages from the small PS board? (+24, +10, +5, etc) ? Put a piece of electrical tape on the chassis before you check the higher pins, so you don't short them to gnd.? -- Craig/W8CS Greenville, SC
Mike Davidsohn G3ZCC All Messages By This Member #81920 Thanks for the tip, checked +10? Tr7 is dead, you can hear a hiss out of the speaker. I know the IFaudio is OK, had another board to try. Radio has had blue led conversion a few years ago, they work as does the fan. No Cal? Thanks Mike? G3ZCC ?

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