EPT360010A - Saturn SSB

[Hawkeye351]

Bout ready to just give up on this one.

Got all those caps checked and put back in.

The 1 ohm resistors measure 1.5 ohm when tested.

Replaced driver bias VR.

SAME result, dead key on sideband, plus I noticed sideband has noise in it (prolly due to the carrier being present on sideband). Still 30w.

Went ahead and just locked the key down for 10 minutes. The regulator/IC side got scorching hot within 3 minutes, then started cooling back down on its own and stayed just warm the rest of the 10 minutes.

Finals got warm but not hot. I did notice that the caps I removed and checked in front of the last final got extremely hot within that 10 minute locked key.

Power gradually dropped 5w within that 10 minutes, but then gradyally came back up and stabilized at 30w.

Both the final bias VRs will adjust fine with the new VRs installed. But the driver bias still will not drop below .64a even with a new driver bias VR.

I did do one little trick I normally do on these radios. I replaced R174 (10k) to a 2.2k and R187 (10k) to a 2.2k. Could that trick cause this issue? Never had an issue using that trick on any other saturn style radios, but then again I've never done a 10a board before. This couldn't be the issue would it?

 

[Hawkeye351]

Got it!!!!

Whew, took a while, but she's back alive with great receive in all modes and all bands, great output power in all modes on all bands. All features working as it should, no heating issues, erratic behavior, etc....just smooth operation.

Turned out when I was frustrated with it and about to give up on it, I didn't pay attention when replacing D15 and D16. I had D16 in backwards. After correcting the orientation of D16, everything went smoothly from there on. Why would D16 have this major affect on xmit? I thought those diodes (15 and 16) were for receive.

Figured this may have damaged something, so I checked over the traces, resistors, voltages, etc...and everything seems to still be in range. Gonna go with it.

Thank you all for helping me get receive back up and running. Not sure why D16 being in backwards didn't affect receive but it did transmit.

The owner (73yr old man) is gonna be so happy to get this radio back. It's been in a mess for years and he had just given up on it cause no other techs would touch it. Not sure why, lol...

Note to self:
Don't rush when frustrated, just walk away, then double check your work when returning.

 

[Handy Andy]

D15 and D16 - we would not have guessed that one!

However though, if the diodes were installed wrong - yes it will have an impact of receive - considerably - for they are part of a limiter function in the RX input - they are the PIN diodes used to attenuate the strong RF signals.

So all the effort you worked on in getting those coil cans and all the other stuff, if you feel it was in vain, please do not think that!

Look at what you did to recover much of the receive (and perhaps more) than what it came to you in that condition.

 

[TM86]

Bravo, sir! Excellent work.

 

[Hawkeye351]

Thank y'all... You're names have already been mentioned to the owner as helping out. He is very happy to hear the news. He said to tell all involved thank you.

Another charity rework so to speak. It's a hobby, I enjoy this.

I know I ask some of the dumbest questions of you guys, but I'm striving to learn more. You guys have a nice way of simplifying things and teaching through your detailed explanations. I thank you guys more than you know.

On to the next one. These locals need to find them a full time tech, lol....

 

[Hawkeye351]

Update:

The owner is very pleased with the results. He wanted me to tell everyone involved in getting it back to factory specs a big thank you. He said if you ever hear him out there then please give him a shout, he goes by Nasty Nite around local and goes by Shadow Walker in skip. He said he's never sending it to another truck stop shop, lol...

Thank you all again for making another old man happy, I couldn't have done it without y'alls help.