For the alignment, I am not able to get the 34 MHz frequency's, it stops around 32.980MHz or so. I tried adjusting for the LSB, AM, USB, and the frequency will not go pass 33.000 MHZ ? Am I doing something wrong or will I need to replace 1 or a few crystals to reach this frequency. Now it is stuck around 32.609MHZ, will not go any further? Any help would be appreciated. Thank you.
-
You can now help support WorldwideDX when you shop on Amazon at no additional cost to you! Simply follow this Shop on Amazon link first and a portion of any purchase is sent to WorldwideDX to help with site costs.
148GTL cannot get the 34.985 ,34.9835 ,34.9865MHz Freq
- Thread starter Mark A Bradley
- Start date
Sounds to me as if you don't have any tuning voltage. If that's a true reading of the VCO's operating frequency, this is the only way the frequency can pull that low.
This reading tells you that the PLL is not locked. Most-common cause for this would be for the 10.24 MHz crystal to stop running. If it checks okay, next place to look would be the 11.325 crystal and L21. The 11.325 crystal feeds into L21, which is tuned to the third harmonic of the crystal. About 33.975 MHz. If the output from L21 is weak or missing, the PLL will behave the way you describe.
Only way I know to verify the crystal and L21 both at once is with a 'scope watching TP10. L21 gets tuned for max signal level.
Never learned to fix or troubleshoot a PLL without a 'scope.
Never had to. Thank goodness.
73
This reading tells you that the PLL is not locked. Most-common cause for this would be for the 10.24 MHz crystal to stop running. If it checks okay, next place to look would be the 11.325 crystal and L21. The 11.325 crystal feeds into L21, which is tuned to the third harmonic of the crystal. About 33.975 MHz. If the output from L21 is weak or missing, the PLL will behave the way you describe.
Only way I know to verify the crystal and L21 both at once is with a 'scope watching TP10. L21 gets tuned for max signal level.
Never learned to fix or troubleshoot a PLL without a 'scope.
Never had to. Thank goodness.
73
Is this the first time you have checked this 148GTL test point with this counter? If not, it could also be the counter's input isn't sensitive enough for the signal you are checking. This scenario can cause the counter to not quite "lock" onto the frequency. I always try another counter before I decide that there is something wrong with a frequency I'm checking, especially if the number is roaming around just below the specified frequency.
Sorry for late reply,,I now have the frequencies, no idea, they showed up,,now I cannot set the 3.2V on channel 1, and 4.2V on 40. The L19 moves like 3 total numbers,,stuck on 2.33V,,only move to 2.35V,,turning all the way. I checked C93,it is before L19,has over 2.00V,,,now I am lost. Any sure way of removing stuck cores in the tuning pots? I have one cracked, and won't move, slots cracked already, I swear this radio is screwing around with my head, nothing going right with this one, I just bought this, seems it may have extras, there are 2 more crystals added in the front of the radio, and wires going to the pads, first I have to remove the core,I also found some burnt up diodes. What you need me to figure out, I cannot align with a srewed up pot
Which cans have the broken cores? I have a parts radio that I may be able to help with.
To remove broken cores, de-solder the transformer from the board and run the core out from the bottom end. The hole and the threads go all the way through. Usually the screwdriver slot on the bottom of the core will still be intact allowing you to furn the core. If you replace the core with one out of a parts radio be sure to use one from the same part # transformer so you know it's made from the same material. You can re-use the cracked core in a pinch by making sure there isn't any core remnants left in the threads of the transformer, then carefully running the cracked core in from the top, broken end first.
Last edited:
Hoping this might help....
[edited to add]
Parts of this may not apply to your case.
I think he is focusing to some degree on the fact that some manufacturers used a real CEMENT.... not wax. For that reason the cement would have more likelihood of hardening, locking the core in place and becoming a problem turning AND getting out.
Still.... seeing him mess with it could be helpful.
[edited to add]
Parts of this may not apply to your case.
I think he is focusing to some degree on the fact that some manufacturers used a real CEMENT.... not wax. For that reason the cement would have more likelihood of hardening, locking the core in place and becoming a problem turning AND getting out.
Still.... seeing him mess with it could be helpful.
Last edited:
This core is completely screwed up, rounded, no slots left, I got pissed off and went to town and made it worse. I will soak it, and use a left hand drill bit and hope it grabs and pulls it out, tomorrows adventure, or I could call Ken's Electronics, I think they showed them in stock, have to call, it was l23 for a 148GTL, gonna try them before hurting myself drilling this little guy out, probably drill my finger instead.
Yeah, I know it's missing. It went to another member for a 2000 that he's working on.
I don't know if any of the other ones on the board are the same value or not, and I don't know where to find that information.
I don't know if any of the other ones on the board are the same value or not, and I don't know where to find that information.
Hey, thank you for the offer, going to the garage shortly and try to remove this core, going to have a few beers then tackle this totally uncalled for waste of my time and makes me mad, total garbage, can you tell I have better thigs to do that to fight a little piece of sh-t. I could be tuning the 148,,but I have to fix someone's glue job... I will give update after I ( try ) to get this out,Mark