RWOB and heat problem is gone.
Mike
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2sb817 upgrade? Dual final 959 needs a better regulator.
- Thread starter Alex Faught
- Start date
Mike
"Bigger is better" 
!?
Mobile AM only, modulation transformer shown for scale.
(compared to the smaller part simply mounted to the side of the chassis, this would seem to create less heat, IMHO)
!?Mobile AM only, modulation transformer shown for scale.
(compared to the smaller part simply mounted to the side of the chassis, this would seem to create less heat, IMHO)
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Back in high school, I use to make larger heatsinks, on the horizontal mill by hand, to fit the Galaxy/RCI chassis for people who modded their rigs push every watt out the back. They looked good and worked well.
can I do the npc-rc and rwob mod to my galaxy 99v that has been up graded to 3 irf520?
Shadetree Mechanic
Delaware Base Station 808
That depends on what kind of "modification" and who performs the work.
I'm not sure what mod you are referring to.
If it is the RWOB mod, then I found this on google:
Usually SSB can still function, but if the radio gets "butchered for AM", in the process SSB can suffer, removed limiters in the audio chain can cause issues, and bias concerns come to mind, it all depends on what exactly is performed on the radio.
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No negative impact on SSB. Finals will get 0.7V more voltage.
Mike
Mike
Have you tried up grading your power wires? Most I have seen are too thin to feed a dual final radio.
You have shown me the way sp5it.
I am going to try this with an irfz24n on a 959 in the near future. tempted to do it to my 2517 but I need to keep it a low drive machine for my old sweep tubes.
so an old post, to a common problem.
the first thing to do to any of these radios, especially if
somebody has been playing inside the transmitter circuit,
and touched by the "Golden Screwdriver"
is to check the bias current on the RF driver and final transistors.
if this bias is high, that series modulation transistor (Q54 on this DX-959)
will get warmer than normal. maybe hot.
I had one radio that was worked on (2970N3) and when I keyed up in
SSB mode, and current draw from the power supply was about 10 amps!!!!!!
No wonder it got hot, and did not work.
Adjust for bias current draw, not the voltage at the gate.
the first thing to do to any of these radios, especially if
somebody has been playing inside the transmitter circuit,
and touched by the "Golden Screwdriver"
is to check the bias current on the RF driver and final transistors.
if this bias is high, that series modulation transistor (Q54 on this DX-959)
will get warmer than normal. maybe hot.
I had one radio that was worked on (2970N3) and when I keyed up in
SSB mode, and current draw from the power supply was about 10 amps!!!!!!
No wonder it got hot, and did not work.
Adjust for bias current draw, not the voltage at the gate.
Wrong. Q54 is getting hot because of high current flow through with high AM carrier plus audio, not bias.
Mike
Checking the Bias for IDLE current first - don't try and presume VOLTAGE is the way to go.
So to set BIAS first will set the DRAW current for the IDLE and power, but too much IDLE Voltage (hence the focus on Current not Voltage) you'll begin to LOSE power in SSB mode and cause a runaway thermal heating problem in any mode that keeps the Gates too much ON - not enough OFF.
So to set BIAS first will set the DRAW current for the IDLE and power, but too much IDLE Voltage (hence the focus on Current not Voltage) you'll begin to LOSE power in SSB mode and cause a runaway thermal heating problem in any mode that keeps the Gates too much ON - not enough OFF.