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playing "armchair technician" just checked out the schematic to that radio. so with a regular mic plugged in, does the PA work? loud audio there? and receiver audio in the speaker? If yes, then maybe a problem in the ALC circuit. for TX modulation, and that audio ALC circuit. turn RV102 to...

brandon7861 says - - "*Someone* should redraw that AGC path and the detector circuit in a way that makes it easier on the eyes (and brain)." yes! much agreed. it is hard to see clearly on the schematic. but on the old 2970 I successfully got working on strong SSB signals. I found, I think...

just got home from a long day at work. yes C73 on the 14B board, going to the product detector. for TP6 I added more RF osc signal on this older 2970 with a 013 board and the cap is C90. I could see on the scope that the carrier level was low, so put in a 100 pico-F and strong SSB signals are...

transistor TR30 should be good. don't mess with it. TX in SSB and AM is working. you can see that the AGC is working. the S-meter is moving is a good indication of that, and it works in AM receive.

transistor TR30 should be good. don't mess with it.

hold everything.... the SSB receive signal in this design takes a different path at the end. there is extra gain and transformers to tune (L13 and L14). and AGC is separate at the end. there is not enough carrier injection from the transistor TR30 carrier oscillator to the SSB receiver...

- about that diode D90 in the Saturn. Yesterday I was working on a RCI-2950 (013Z board) and it has diode D93 in that same place. And with full negative going modulation causing the voltage at the TP 7/8/9 shorting board to go to zero, the bias going to the RF driver to drops out, as...

so is your problem in SSB receive? these RCI/Galaxy radios have a problem there. I posted a solution not long ago.

hey, yeah, brandon7861 just got on my computer this evening. I knew what I did and said would get replies. Messing with that "sacred" bias circuit. I was keeping it short, and may not have explained things properly. we are not arguing, it's all cool. We will all learn something. And then...

-"function of D90 and C174 was to keep the collector from going below 8v." if it did that, then the collectors on the other transistor collectors would not go below 8 V, and it would not modulate correctly, as is done with that "NPC mod" that I clip out of radios so they get full modulation...

-- "Was removing galaxy's attempt at negative peak control necessary for the simplified bias at the finals to work? Can you tell us about the journey that led you to yanking those parts?" You must be referring to diode D90 and capacitor C174. this circuit is in most of their radios. I always...

I got this old Galaxy Saturn radio to bring back to life. Working on the RF output. It had several watts of carrier for AM, and SSB was "rough" "scratchy" sounding bad I was told. did the usual RF output transistor bias level check at first. at driver transistor TR44 the bias would barely...

OK, I just repaired an old Galaxy Saturn days ago. (014B board) It was golden screw driver-ed to death, and had various modifications. Just got my new RF output bias circuit tested last night. I ripped out the MV1Y diodes that failed and made a more reliable bias circuit. Just some resistor...

I have read numerous postings about this SSB audio receive problem in these newer 5555 radios. Bad distorted audio on stronger SSB signals. and after this: https://www.worldwidedx.com/threads/old-rci-2970-solved-distorted-receive-in-ssb-mode-with-moderate-to-strong-signals.269528/ . the same...

for modulation problem. maybe??? turn the AMC off. pot VR14 to zero ohms. your audio for AM will cut out if this control is set up high.

yes, on my 148 there is a TIP3055 mounted on the back panel for the modulator. hey dss56 - check that the mod to make the receive RF gain adjusts the AM carrier power. that is how the radio I got did it. so I put it back to stock, and have 3.8 watts carrier. and adjust the bias to the...

is this the made in China D version? got one here. it was given to me. I posted my repairs here. works great on SSB now. check the voltage at PLL IC1-9 is it lower than 8 V? the known problem is R130 10 ohm resistor on the blue wire going down to the circuit board. Replace it with a...

oh, I just did some quick research on that 2990. It has the same boards inside as on the old 2970 I was just repairing. So that TX problem in AM or SSB? Using a battery powered pre-amp mic? in AM turn carrier power down to just over 30 Watts. So capable to do 120 to 140 W PEP out...

that radio has the same main board as most of them RCI/Galaxy radios. yes, check the bias currents to the RF driver and output sections. so if it was changed to MOSFETs, could be a few things done incorrectly.

I have this old 2970 (with the -013 board) that had many problems. it was worked on by others, sometimes making things worse. (solder blob shorts across circuit traces., etc) But the last thing I was trying to repair was while in SSB receive, with even a moderate strength signal, the audio was...