Galaxy Saturn growling noise from echo board

[RF Krazy]

D83 is a 1N60P diode. And yes, this would affect your modulation as it's tied into C133 and TR53, both of which affect the AMC.

Again Thank You Hawkeye.

I found TR53 along with C133 on the board and on the schematic. They both seem to be intact on the board. I still need to replace D83. I did find D83 on the schematic and where it showed 1N60 AM.

Would you happen to know the value of VR14. I am editing this...I found on the schematic where it showed 1K for the value of VR14. Thank you just the same.

I think I will replace VR14 as I see no change when I turn it one way or the other. Unless D83 being cut is the result of VR14 not reacting. I need to look that area over much slower.

Like I mentioned, a lot to chew on. A little at a time but I will work through it.

I appreciate the help from everyone, thank you.

RF Krazy

 

[Hawkeye351]

Yes, VR14 does tie into D83 through TR53. VR14 is a 1k (stamping on VR should be 102).

 

[Hawkeye351]

If R249, TR53 or TR32 are removed, clipped, cut...then VR14 won't do anything.

 

[RF Krazy]

If R249, TR53 or TR32 are removed, clipped, cut...then VR14 won't do anything.

Good Day Hawkeye,

Okay, I replaced D83, I turned the Saturn back on. I keyed up and had no Modulation. I place the radio into SSB and I had audio. So I looked at VR14 and I saw where I left the pot all the way to the left (counter clockwise). So of course I turned it all the way to the right. The audio came in screaming on the REA Mod meter! It looked good on the REA software scope too. And of course the watt meter swung from 3 watts to 39 to 40 watts.

Since I now have control of VR14, I will not be replacing VR14, that's a relief.

But as I turn up the RF potentiometer, the audio still seem to lower itself. When looking at the scope, you can see the wide spacing between the lobes compared to the thin narrow spacing between the lobes when the carrier is down to about 2 to 3 watts. In other words, showing less than 100% when the carrier was turned up. When the carrier was turned down to about 2 to 3 watts, I was able to hit easily over 100% modulation. I understand this is somewhat normal, but the audio still drops beyond what I would call normal if you will.

I have not yet found R249 on the Board itself! It's got to be there, I did find it on the schematic. I will keep looking!!!

I will continue to look over the components that you had mentioned in your previous post. Perhaps I will find something thats still not right.

Again thank you Hawkeye.

RF Krazy

 

[Hawkeye351]

See those resistors around D83 in the first pic above? There are two laying flat (not standing up). One of those is R249 (it's marked on the board). It looks to be connected, so no worries.

If it's swinging 40w max, then turn the RF power knob all the way up, and adjust VR13 for a 9w or 10w deadkey. Then adjust VR14 for 100% modulation.

It'll be difficult to get a decent waveform on the scope for 100% modulation with a 3w key swinging 40w (that's a 13:1, it'll obviously not look good). That's why you set your deadkey level with the RF power all the way up to a 4:1.

Also, in the middle pic above of the trace side of the board (the one you have D83 solder side showing), I see a silicon diode strapped across the regulator, this is a swing mod. This is why the swing is not staying proportional to the carrier. That type of swing mod allows the radio to swing to maximum peak wattage regardless of where you have the deadkey set. This actually makes that regulator get hot, weakening it over time. I would say yank it off, but I'm not sure if they added something else in that circuit on the parts side. May need to take a pic of that area also, but on the component side (parts side) so I can zoom in to verify the parts and placement.

That regulator getting weakened over time will exhibit lower modulation on AM. If that's the case, then you'll need to replace it (the fat one screwed to chassis) with a 2SB817, TIP36C or the original which is usually a 2SB754 or 2SB688. The 817 is the better part, the TIP being second choice. Anytime you replace this regulator, then you should also replace the transistor (1819 or 473) that stands up freely in front of it with a 2SA1012.

Is the modulation on SSB just as low as the modulation on AM? If not, then I would suspect the AM Passthrough regulator (big fat one mounted to side of chassis).

Congrats on getting it going. Don't give up on the other issue, we'll get it.

 

[RF Krazy]

See those resistors around D83 in the first pic above? There are two laying flat (not standing up). One of those is R249 (it's marked on the board). It looks to be connected, so no worries.

If it's swinging 40w max, then turn the RF power knob all the way up, and adjust VR13 for a 9w or 10w deadkey. Then adjust VR14 for 100% modulation.

It'll be difficult to get a decent waveform on the scope for 100% modulation with a 3w key swinging 40w (that's a 13:1, it'll obviously not look good). That's why you set your deadkey level with the RF power all the way up to a 4:1.

Also, in the middle pic above of the trace side of the board (the one you have D83 solder side showing), I see a silicon diode strapped across the regulator, this is a swing mod. This is why the swing is not staying proportional to the carrier. That type of swing mod allows the radio to swing to maximum peak wattage regardless of where you have the deadkey set. This actually makes that regulator get hot, weakening it over time. I would say yank it off, but I'm not sure if they added something else in that circuit on the parts side. May need to take a pic of that area also, but on the component side (parts side) so I can zoom in to verify the parts and placement.

That regulator getting weakened over time will exhibit lower modulation on AM. If that's the case, then you'll need to replace it (the fat one screwed to chassis) with a 2SB817, TIP36C or the original which is usually a 2SB754 or 2SB688. The 817 is the better part, the TIP being second choice. Anytime you replace this regulator, then you should also replace the transistor (1819 or 473) that stands up freely in front of it with a 2SA1012.

Is the modulation on SSB just as low as the modulation on AM? If not, then I would suspect the AM Passthrough regulator (big fat one mounted to side of chassis).

Congrats on getting it going. Don't give up on the other issue, we'll get it.

Hawkeye,

Wow, you just made my day! I have been looking to undo any mods.

So when you pointed out that diode, I thought to myself, I am going to remove it just to see what will become of the radio. Well low and behold, when I turn up the RF potentiometer, the mod meter shows an easy 100% modulation with 100% negative peaks like it should.

That diode across the regulator was bogging the audio down on the higher carrier settings.

Its been a long time since I worked on these radios on my own, and never this one.

You guys here are just awesome! As some of you know we didn't have forums back in the 70s and 80s. You had to burn up some radios with a Golden Screwdriver until you learn the In-s and Out-s.

Hawkeye, you have no idea, how much I am smiling because of what you just taught me.

I am leaving a pic of the Top Side just in case there is something else that was installed. Also a pic of the removed diode. I placed some marks on the board showing me where the diode was installed. The mark on the far right is just a mark to represent how the diode was installed. (For my understanding only!)

Man you made my day!

RF Krazy

 

[Hawkeye351]

I see a "simple swing" mod also in the top pic above. This simple swing mod I see no problem with, I use it myself also at times. But in order to go back factory I would remove it.

The one I'm referring to is located right in front of VR13 (AM HI deadkey adjustment). It's marked as R238, originally it should be just a 5.6k ohm resistor, no black or glass diode tied in with it. This mod will also allow full swing regardless of deadkey, it's just not as hard on the regulator and you can align it out to look decent on a scope and analyzer.

Great job, you stuck with it and didn't give up.

Now, as far the growling echo, if a recap and reflow of the board, along with checking parts doesn't work, I normally disconnect them totally (bypass the board).

Also, one last thing we didn't check: how is the transmit audio on FM mode? Non-existent, low or bout normal?

 

[RF Krazy]

I see a "simple swing" mod also in the top pic above. This simple swing mod I see no problem with, I use it myself also at times. But in order to go back factory I would remove it.

The one I'm referring to is located right in front of VR13 (AM HI deadkey adjustment). It's marked as R238, originally it should be just a 5.6k ohm resistor, no black or glass diode tied in with it. This mod will also allow full swing regardless of deadkey, it's just not as hard on the regulator and you can align it out to look decent on a scope and analyzer.

Great job, you stuck with it and didn't give up.

Now, as far the growling echo, if a recap and reflow of the board, along with checking parts doesn't work, I normally disconnect them totally (bypass the board).

Also, one last thing we didn't check: how is the transmit audio on FM mode? Non-existent, low or bout normal?

Now I know why you call yourself Hawkeye!

You surely have an eye for finding things. I can see myself not seeing that diode on the regulator I suppose. But I surely should had seen the diode tied to the 5.6k resistor.

I am just not familiar with these mods. I am very old school from way back when. We did channel mods, added VFOs, average peaks along with alignments, replace parts when needed. Played with noise toys, actual audio gear connected to the radios. I had gotten out of CB radios and just dabbled in them here and there.

I do appreciate your kind words. Yes I stuck with it, but everyone here who had helped was the reason I was able to.

I probably will remove the diode thats tied into the 5.6k resistor, and then observe the differences in how it performs.

As for the growling, I had fixed that early on. It was due to operator error, go figure! If I remember right, I wired the radios mic jack in reverse. I had the radio on its side or I had the radio upside down, something like that. And so I was not thinking during the rewiring.

Some how the echo board had gotten shorted, so I took it completely out and connected the two wires from the in and out together that went to the board.

The big issue was TR32, the trim pots for the finals along with the 1 ohm resistor replacement and that diode connected to the regulator. The diode connected to the regulator being the biggest.

I also had to re-solder some connections and add new traces to the frequency board. As it would blank out now and then and some of the digits would not all light up.

I don't know Hawkeye, but I do know I would still be here scratching my head if it wasn't for you pointing out the regulator mod. Instead of scratching my head, I am just just shaking my head back and forth in unbelief.

A Big Blessing thank you to you, and of course to everyone here who chimed in and lend a hand. I could not had put this radio back to where it belongs, if it wasn't for everyone who had help. You guys are the greatest, Thank you.

RF Krazy

 

[Hawkeye351]

No problem Krazy,
Hope to hear you in skipland sometime.
On CB I hang on channel 40 AM, 29 AM, sometimes channel 1 AM and I go by 351 around the Carolinas.
Peace...

 

[RF Krazy]

No problem Krazy,
Hope to hear you in skipland sometime.
On CB I hang on channel 40 AM, 29 AM, sometimes channel 1 AM and I go by 351 around the Carolinas.
Peace...

Hello Hawkeye,

I will defiantly look you up. I am in Tennessee, so it shouldn't be to hard
to hook up.

I use the numbers 833. The same tube numbers in a Gate Transmitter!

I disconnected that other swing mod with the diode connected to the 5.6k resistor. The swing does look better, but I rather have it stock for the most part. With an amplified mic and a box tied in-between, that works enough for me.

I still can't get over the idea of that diode connected to the regulator, that it was the reason causing the audio to bog down when turning up the carrier. But its doing its thing, and I am as happy as one can be!

Thanks a million Hawkeye.

RF Krazy