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EPT360015C Connex cx3400hp dual mosfet issue.
- Thread starter Hawkeye351
- Start date
My 872 reads 31 watts when on the pep setting, but my 868 reads 37 almost 40 watts when set on peak. I bought both meters new, no one has ever been in neither one.
But, both meters read about the same on rms and avg.
872 on avg reads about 16 to 18.
868 on rms reads about 15 to 19.
Above info was with power all the way up.
Gonna finish up when I get home.
But, both meters read about the same on rms and avg.
872 on avg reads about 16 to 18.
868 on rms reads about 15 to 19.
Above info was with power all the way up.
Gonna finish up when I get home.
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Wow - was describing IF ANY radio (he has 3) that need work - please review the threads beginning before this goes too far. Each will need a Base line - so while everyone jumps on the posters -
Where in the H*LL were all of you earlier?
Geez, give a guy some space to work and you come in taking the whole counter...
I'm stepping back I guess my job is done!
Where in the H*LL were all of you earlier?
Geez, give a guy some space to work and you come in taking the whole counter...
I'm stepping back I guess my job is done!
No Andy, please don't leave me hangin, I need you dawg... I'm gonna try to finish up tonight, after the girls give me my birthday cake and presents.
Yes - Happy Birthday!
May you have Many more!
Not sure what the other kids want at the party - but I'm still here to help get you thru this and let the other kids play and crash the jungle Jim jumper.
-------
But I'd like to know if the Radio survived, and how it does in FM mode - although the AM Regulator does more linear operation in AM, it does act as a simple regulator in FM - but it is VARIABLE - so FM being more demanding in current - I am hoping the thermal problem is fixed.
Keeping the Gate Bias low helps IMMENSELY in FM mode - but would like to make sure the Regulator is also not being bled to death from excessive current demands forcing it to drop the voltage as a big resistor that will just heat up.
May you have Many more!
Not sure what the other kids want at the party - but I'm still here to help get you thru this and let the other kids play and crash the jungle Jim jumper.
-------
But I'd like to know if the Radio survived, and how it does in FM mode - although the AM Regulator does more linear operation in AM, it does act as a simple regulator in FM - but it is VARIABLE - so FM being more demanding in current - I am hoping the thermal problem is fixed.
Keeping the Gate Bias low helps IMMENSELY in FM mode - but would like to make sure the Regulator is also not being bled to death from excessive current demands forcing it to drop the voltage as a big resistor that will just heat up.
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Set all gate trimmers to 3.0v
Got all 3 mosfets resoldered
Keyed up to check gate voltage going to the driver mosfet. It showed 3.45v and gradually dropped back to 2.96v. Both final gate voltages did the same thing, started at around 3.4v and gradually dropped to 2.96v. AM regulator still gets hot. Did not check power output, don't want to know until it's ready, although I did see a 16 watt key with rf power all the way up and 1 watt all the way down. Amperes from power supply stayed very low.
Got all 3 mosfets resoldered
Keyed up to check gate voltage going to the driver mosfet. It showed 3.45v and gradually dropped back to 2.96v. Both final gate voltages did the same thing, started at around 3.4v and gradually dropped to 2.96v. AM regulator still gets hot. Did not check power output, don't want to know until it's ready, although I did see a 16 watt key with rf power all the way up and 1 watt all the way down. Amperes from power supply stayed very low.
Placed diodes back on each mosfet, checked Gates again on each mosfet with same results. On key up it starts at 3.4v and gradually drops to 2.96v on each mosfet gate. Did check power output this time, hi power 10 watts (I brought it down) swinging to 34 watts peak, lo power 1 watt swinging 34 watts peak. Hi power rms swing is 18 watts rms, lo power swinging 14 watts rms. Regulator gets hot after 5 minutes of key, mosfets and everything else is cool to warm.
FM works, variable power works as it should on FM and I have audio, but the regulator gets hot within 5 minutes, like am. Mosfets and everything else is cool to warm.
Do these look to be reliable components?
Is the tip36c the right one?
Are the mosfets the right ones?
Got both from digikey.
Do these look to be reliable components?
Is the tip36c the right one?
Are the mosfets the right ones?
Got both from digikey.
The AM Regulator is what it is - what is the value of C190? The working gain cell cap value? Should be 100uF.
C174 in your photo is a 2.2uF - is that original? If so, try changing it out - use same value / rating - just fresher.
16(!?!) watts is a bit high - for FM so go to the AM Regulator section and look at any trimmer controls that are NOT set to mid point - I'm thinking AMC - but right now anything goes...why this? To make sure we didn't inadvertently set a control too high and it's killing the Regulator.
Your parts? Seem ok - don't APPEAR to be fakes - but heat is a concern so to me the FM mode seems a bit high but she's working and the voltages seem stable - the "FADE" is from the biasing and the stability - so if they are staying pretty cool - are those trimmers for Final and Driver at or near mid point?
The AM Regulator - when tasked to deliver will heat up but when you're running 4 watts and your able to cook marshmallows off the rear panel - then yes, there is something still going on back there.
C174 in your photo is a 2.2uF - is that original? If so, try changing it out - use same value / rating - just fresher.
16(!?!) watts is a bit high - for FM so go to the AM Regulator section and look at any trimmer controls that are NOT set to mid point - I'm thinking AMC - but right now anything goes...why this? To make sure we didn't inadvertently set a control too high and it's killing the Regulator.
Your parts? Seem ok - don't APPEAR to be fakes - but heat is a concern so to me the FM mode seems a bit high but she's working and the voltages seem stable - the "FADE" is from the biasing and the stability - so if they are staying pretty cool - are those trimmers for Final and Driver at or near mid point?
The AM Regulator - when tasked to deliver will heat up but when you're running 4 watts and your able to cook marshmallows off the rear panel - then yes, there is something still going on back there.
Driver trimmer is halfway, the 2 final trimmers are slightly off halfway.
Here's a pic of current positions:
Here's a pic of current positions:
Sorry for my voltage numbers earlier, I had the ground of my meter on the chassis, not board ground.
Board ground:
Driver = 3.97v
1st final 3.99v
2nd final = 3.98v
Was checking something earlier that required chassis ground and just forgot.
Board ground:
Driver = 3.97v
1st final 3.99v
2nd final = 3.98v
Was checking something earlier that required chassis ground and just forgot.
Oh boy..., Driver and Finals are running high
Back them down!
You will need to do the mA draw - the AM Regulator is getting fried from this...
So go do the mA Draw like we said/described - instructed before it's too late...
Added, when they are to the right (Trimmers position) then you're forcing a bit more current thru - better redo the mA Draw
The Zeners HAVE TO GO IN! They are protecting (By their actions) Not just the Gates, the AM Regulator too...
See post #31
https://www.worldwidedx.com/threads...p-dual-mosfet-issue.262896/page-3#post-777652
Notice the Trimmers in the 1st pic show md-point...
Driver if thats in Mid point - even the 55K will need some help - so follow #31 suggested...
Back them down!
You will need to do the mA draw - the AM Regulator is getting fried from this...
So go do the mA Draw like we said/described - instructed before it's too late...
Added, when they are to the right (Trimmers position) then you're forcing a bit more current thru - better redo the mA Draw
The Zeners HAVE TO GO IN! They are protecting (By their actions) Not just the Gates, the AM Regulator too...
See post #31
https://www.worldwidedx.com/threads...p-dual-mosfet-issue.262896/page-3#post-777652
Notice the Trimmers in the 1st pic show md-point...
Driver if thats in Mid point - even the 55K will need some help - so follow #31 suggested...
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