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RCI 2995DX power issue

C

Crambone

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Jan 22, 2019
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I’m only seeing 1.7 - 10 watts output on AM and 0 - 10 on SSB
I checked Q66 VR (2SB754Y) and I’m seeing 12v at all 3 legs. I popped off the legs and I’m seeing on the CPU Pads 13.7V, 1.2V & 1.4V???
Should I be seeing voltage on the 2 contacts? I know the 13.7 is ok but not sure about the other 2?
I also checked Bias and it seems like my mA are low on Q62 across TP7 & TP9.

Any suggestions?

Drew
 

Ok what about the variable power control on the front of the radio does it vary the power levels when adjusted?
I assume you mean the circuit board not the CPU board, Anyway there should not be 13+ volts on all three legs so I assume you have tested the (2SB754Y) this being the main modulated supply for the final section would show full power readings if there is as you say 13+ volts on all three legs of the (2SB754Y) when the power level is adjusted total counter clockwise it would most likely be around 2 watts depending on how the limits are adjusted for low and high power.
Next I would ask what does the Modulation levels look like if that is good and the front panel power control is functioning as it should and the voltage levels at the collectors of the driver and final are going up with modulation levels then the issue may be elsewhere in the RF chain from the before the mixer stage or after.
 
First thing I check is to unplug the two-wire lead that serves to key the amplifier in the rear. Need to know what power the barefoot radio delivers before looking deeper. Got a pic of that somewhere. I'll see if I can find it.

73
 
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OldTech03 said:
Ok what about the variable power control on the front of the radio does it vary the power levels when adjusted?
I assume you mean the circuit board not the CPU board, Anyway there should not be 13+ volts on all three legs so I assume you have tested the (2SB754Y) this being the main modulated supply for the final section would show full power readings if there is as you say 13+ volts on all three legs of the (2SB754Y) when the power level is adjusted total counter clockwise it would most likely be around 2 watts depending on how the limits are adjusted for low and high power.
Next I would ask what does the Modulation levels look like if that is good and the front panel power control is functioning as it should and the voltage levels at the collectors of the driver and final are going up with modulation levels then the issue may be elsewhere in the RF chain from the before the mixer stage or after.
Click to expand...
nomadradio said:
First thing I check is to unplug the two-wire lead that serves to key the amplifier in the rear. Need to know what power the barefoot radio delivers before looking deeper. Got a pic of that somewhere. I'll see if I can find it.

73
Click to expand...
Hello Nomad, I should have stated that I unplugged the amp keying 2 wires.
 
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OldTech03 said:
Ok what about the variable power control on the front of the radio does it vary the power levels when adjusted?
I assume you mean the circuit board not the CPU board, Anyway there should not be 13+ volts on all three legs so I assume you have tested the (2SB754Y) this being the main modulated supply for the final section would show full power readings if there is as you say 13+ volts on all three legs of the (2SB754Y) when the power level is adjusted total counter clockwise it would most likely be around 2 watts depending on how the limits are adjusted for low and high power.
Next I would ask what does the Modulation levels look like if that is good and the front panel power control is functioning as it should and the voltage levels at the collectors of the driver and final are going up with modulation levels then the issue may be elsewhere in the RF chain from the before the mixer stage or after.
Click to expand...
Variable RF Power control
CCW .2 watts
CW 1.4 watts

VR 2SB754Y tests good

I tested voltages on the following also

Q62 IFR520
RX. TX
G. 35mV. 4.3V
D. 6.26V. 6V
S. 0. 1.1mV

Q60 IFR520
RX. TX
G. 28mV. 3.5V
D. 6.26V. 6V
S. 0. 1.1mV

Q63 2SC2314
RX. TX
B. 0. .68V
C. 67mV. 7.9V
E. 12mV. 1.37V
 
OK to make sure it wasn’t in the amplifier I totally removed and connected one of the coaxes from bottom side to main board. I just wanted to make sure the amp wasn’t in the chain at all. Still same results as I assumed but it does make it easier to move around now.
 
If this is the pre-2006 version with two 2SC2290 in the amplifier, you shouldn't see more than ten or twelve Watts PEP from the barefoot radio. That's really all it takes to drive the heck out of two 2290s.

Had a customer years ago who liked his Galaxy Saturn Turbo. He had a friend ask for him, how much to install that second final in the radio circuit board. When that radio's main circuit board was used in a mobile model, it had two final transistors in parallel. But in the Turbo, one of the two spots is empty. Told him five hundred bucks. The added drive would just make it sound bad and wear things out prematurely. If I make it sound that bad with my name attached, you'll make it worth my while. He wisely declined my offer.

73
 
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nomadradio said:
If this is the pre-2006 version with two 2SC2290 in the amplifier, you shouldn't see more than ten or twelve Watts PEP from the barefoot radio. That's really all it takes to drive the heck out of two 2290s.

Had a customer years ago who liked his Galaxy Saturn Turbo. He had a friend ask for him, how much to install that second final in the radio circuit board. When that radio's main circuit board was used in a mobile model, it had two final transistors in parallel. But in the Turbo, one of the two spots is empty. Told him five hundred bucks. The added drive would just make it sound bad and wear things out prematurely. If I make it sound that bad with my name attached, you'll make it worth my while. He wisely declined my offer.

73
Click to expand...
Unfortune
nomadradio said:
If this is the pre-2006 version with two 2SC2290 in the amplifier, you shouldn't see more than ten or twelve Watts PEP from the barefoot radio. That's really all it takes to drive the heck out of two 2290s.

Had a customer years ago who liked his Galaxy Saturn Turbo. He had a friend ask for him, how much to install that second final in the radio circuit board. When that radio's main circuit board was used in a mobile model, it had two final transistors in parallel. But in the Turbo, one of the two spots is empty. Told him five hundred bucks. The added drive would just make it sound bad and wear things out prematurely. If I make it sound that bad with my name attached, you'll make it worth my while. He wisely declined my offer.

73
Click to expand...
Unfortunately it’s the 4 R5 transistor's that I believe may be IRF520’s also? It was putting out 7 watts dead key and 23 watts modulated with the amp keying 2 wires disconnected. Something went wrong?
 
This is where the 30-buck chinesium fleabay tranistor tester pays for itself. Odds are most of the four linear MOSFETs are croaked. No good way to test them with only a multimeter. Got in the habit of calling that linear stage the firestarter junior.

PL9wvs.jpg


But they can fail and still look okay on the outside. Time to find out.

73
 
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Well I found the issue it was the voltage regulator, tested good with cheap Chinese tester but when bench tested with power supply no good.
 
On another note it has the R2 adjustment for the “fire starter” and was wondering if that is what’s set wrong causing the issue with the amp board?
 

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