RCI6900F150

[eyecue]

Trying to align this bad boy and when I switch to USB or LSB the 10.695 MHz oscillator goes into a weak signal and cant be seen on anything but a spectrum analyzer . It is so low it barely comes out of the noise floor. AM is fine all day. I am putting 1kHz tone at 30mV in the mic jack. Any ideas? RCI response is crickets.
Thanks

 

[BayouRadioAmplifier]

on them there RCI/Galaxy boards, I would just take my
scope probe at "X1" setting to the case of that 10.695 crystal
and adjust L18/19/20 having the output of scope to my freq counter.
using the oscilloscope as an amplifier to feed my external counter.
(I have all old (like me!) primitive equipment)
but sometimes the crystal case is soldered to ground with a wire
or soldered to one of them inductor shields. you can unsolder it.

or just cram the scope probe tip around that oscillator
transistor Q58. or put probe in "X10" and touch somewhere
around there.

 

[brandon7861]

If ranger/galaxy would have just used the same test point numbers across all their schematics...

CBtricks service manual states using TP5, and on this particular schematic, TP5 is the audio input. You won't find much RF on that test point.

Other manuals/schematics, such as the galaxy 959 and the ranger 2950, also state to use TP5, but in those schematics, TP5 is the balanced mod output, not the baseband input.

Thats not the end of the story, because the carrier of the balanced modulator is suppressed (thats the whole idea of a balanced modulator, right?), so how are you supposed to measure a sideband carrier coming out of something that suppresses it?

Easy, you intentionally unbalance the modulator and key up with no modulation. What you want to do is turn that bal mod pot a little to get some carrier out of it for the alignment, and then once you get the two sideband frequencies set, use your scope to readjust the pot for a carrier null.

 

[eyecue]

on them there RCI/Galaxy boards, I would just take my
scope probe at "X1" setting to the case of that 10.695 crystal
and adjust L18/19/20 having the output of scope to my freq counter.
using the oscilloscope as an amplifier to feed my external counter.
(I have all old (like me!) primitive equipment)
but sometimes the crystal case is soldered to ground with a wire
or soldered to one of them inductor shields. you can unsolder it.

or just cram the scope probe tip around that oscillator
transistor Q58. or put probe in "X10" and touch somewhere
around there.

Thank you for the reply! I was able to get them set by going to probe the capacitor near the cans. BUT something is pulling the SSB osc so low that the output is garbage. The only thing I think it could be the switching diodes on the mode switch. This radio is SMT and that is not good for me.

 

[eyecue]

If ranger/galaxy would have just used the same test point numbers across all their schematics...

CBtricks service manual states using TP5, and on this particular schematic, TP5 is the audio input. You won't find much RF on that test point.

Other manuals/schematics, such as the galaxy 959 and the ranger 2950, also state to use TP5, but in those schematics, TP5 is the balanced mod output, not the baseband input.

Thats not the end of the story, because the carrier of the balanced modulator is suppressed (thats the whole idea of a balanced modulator, right?), so how are you supposed to measure a sideband carrier coming out of something that suppresses it?

Easy, you intentionally unbalance the modulator and key up with no modulation. What you want to do is turn that bal mod pot a little to get some carrier out of it for the alignment, and then once you get the two sideband frequencies set, use your scope to readjust the pot for a carrier null.

I went that route with VR7 early on and no joy. TP5 reads AM fine but when changed to SSB the osc level drops into -53dBm range. You are right about changing labels on things.