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Galaxy dx94 amp regulator help needed.

morseguy

Member
Jun 16, 2013
42
9
18
Earth
Hi everyone long time lurker here.
After seeing some of the mods for the galaxy dx 959 I decided to try some of them on my 94 since they both share the 6900 series main board.
I replaced q54 (stock 2sb827) amp voltage regulator with a ecg37 (2sb817 equivalent ).
This is supposed to provide better voltage regulation for peaked radios.
Before the mod my 94hp had an am dead key of 35 watts (per the service manual) and a swing of about 130 watts pep.
Now when I key the mic I get a dead key of 130 watts! Even with zero mic gain. I only keyed a couple of times real quick so as not to blow the finals. SSB seems normal.
I've checked my work and it looks okay. I've been tinkering with radio's for along time but this has me baffled.
Any help will be greatly appreciated.
Dave
 
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The Galaxy 94 is a higher powered export radio, the 959 is a cb set. Might have the same basic board but many mods that work on the 959 will not on a 94. Put the 94 back the way it was, convert it, give it a correct complete alignment and your done. It will be all it can be and needs nothing else.
 
The 2SB817 should have worked fine. The radio itself is just a single final radio driving that PA board, so it's really not much different than a DX949 or 959, other than a few added features. Same basic board.

I have had instances where installing the 2SB817 did the same thing to me in certain radios. Turns out that the 2SB817 was junk from the manufacturer. Sometimes the 817's have been hit and miss for me in the past, but I no longer install them.

If you really want to upgrade the regulator circuit, I highly recommend replacing the original 2SB827 with a TIP36C. It's a 25 amp, 125 watt transistor.... double the specs of the 2SB827. I'd also replace Q55 (2SA1869) with a TIP42C. Q55 is located right in front of Q54, it's the smaller transistor that's free standing, not bolted to anything.

Give that a try and let us know how you get on.

~Cheers~
 
The 2SB817 should have worked fine. The radio itself is just a single final radio driving that PA board, so it's really not much different than a DX949 or 959, other than a few added features. Same basic board.

I have had instances where installing the 2SB817 did the same thing to me in certain radios. Turns out that the 2SB817 was junk from the manufacturer. Sometimes the 817's have been hit and miss for me in the past, but I no longer install them.

If you really want to upgrade the regulator circuit, I highly recommend replacing the original 2SB827 with a TIP36C. It's a 25 amp, 125 watt transistor.... double the specs of the 2SB827. I'd also replace Q55 (2SA1869) with a TIP42C. Q55 is located right in front of Q54, it's the smaller transistor that's free standing, not bolted to anything.

Give that a try and let us know how you get on.

~Cheers~
 
Thanks for the replies, guys.
Did it work?


~Cheers~
I don't know what happened with my post, rest never got posted.
Anyway, before doing q54, I swapped out q55(mine was 2sa1869) with Nte153 and that worked fine. This was to get more mic gain when using a non amplified noise cancelling mic. Regarding my original problem at q54 I have heard of people having problems with nte37 transistors. Those TIP numbers sound interesting, I 'll have to order some. Before I read your post, I ordered a hopefully genuine Sanyo `817 that should be here today. Curious to see how that works. The ecg37 seems to have short between the collector and either the base or emitter can't remember which one.
Thanks again, I'll let everyone know.
 
Last edited:
Thanks for the replies, guys.

I don't know what happened with my post, rest never got posted.
Anyway, before doing q54, I swapped out q55(mine was 2sa1869) with Nte153 and that worked fine. This was to get more mic gain when using a non amplified noise cancelling mic. Regarding my original problem at q54 I have heard of people having problems with nte37 transistors. Those TIP numbers sound interesting, I 'll have to order some. Before I read your post, I ordered a hopefully genuine Sanyo `817 that should be here today. Curious to see how that works. The ecg37 seems to have short between the collector and either the base or emitter can't remember which one.
Thanks again, I'll let everyone know.
Thanks for the replies, guys.

I don't know what happened with my post, rest never got posted.
Anyway, before doing q54, I swapped out q55(mine was 2sa1869) with Nte153 and that worked fine. This was to get more mic gain when using a non amplified noise cancelling mic. Regarding my original problem at q54 I have heard of people having problems with nte37 transistors. Those TIP numbers sound interesting, I 'll have to order some. Before I read your post, I ordered a hopefully genuine Sanyo `817 that should be here today. Curious to see how that works. The ecg37 seems to have short between the collector and either the base or emitter can't remember which one.
Thanks again, I'll let everyone know.
Well I installed the new '817 and it worked! So the ecg on was at fault.
Now the bad news.
I was checking the biases. The driver bias was a little off, adjusted that. I have adjusted biases in both radios and audio amps before so I'm familiar with it.
When I was adjusting the final bias I suddenly lost bias, then there was a loud snap and arc with a smell of burning from around the area where the power lead comes into the radio. I m not positive but one of the test leads may have moved and shorted to something.
Now I have no output, but do have receive. Listening on another receiver I get a weak am carrier with no audio. On ssb I get a weak but intelligible signal.
I haven't checked them all but the components in the area where the flash bang occurred, all look fine.
I'm not very good at signal traceing but that's what I need to do, any ideas?
 
Unfortunately, without having the radio in front of me, there's no way for me to diagnose the issue at this point. I would make sure to double check all traces and make sure nothing got burnt.


~Cheers~
 
Bought a couple of those SB817 online from eBay that turned out to be phony/fakes. You cannot trust some of those parts, even from otherwise reliable sellers too . . .
I have put the radio on the "to do list". I just got a 949 and tweaked it up for now. I want to thank you for your post on how to set the final voltage on the new mosfet 949's as the SM on CB tricks is for the old 949's.
Thanks.
 

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