RCI 2995dxfc amplifier

[Ranch55]

Sounds like the internal amplifier board bias voltage is not being set correctly.
I had this same issue until I got some guidance from Handy Andy on setting the amplifier board bias voltage correctly.
Once done correctly, I haven't had any more internal amplifier blow the transistors.

 

[Eldorado828]

Sounds like the internal amplifier board bias voltage is not being set correctly.
I had this same issue until I got some guidance from Handy Andy on setting the amplifier board bias voltage correctly.
Once done correctly, I haven't had any more internal amplifier blow the transistors.

I'm starting to wonder if the Amp board bias is neglected when these shops do their alignments. On the 4 fet board such as the Galaxy 94 hp or x9, there's one pot on that board to control bias but how exactly would one set it correctly.

 

[Ranch55]

I'm starting to wonder if the Amp board bias is neglected when these shops do their alignments. On the 4 fet board such as the Galaxy 94 hp or x9, there's one pot on that board to control bias but how exactly would one set it correctly.

Set up the power supply thru your Ammeter (+) lead and trim Bias watching the mA results you'll have an intitial "Base" mA power consumption reading you start out as your "BASIC"- and the climb curve - on a typical DVM set your meter to 200mA or 2A (2000mA) just so you can see the "switch on - voltages" - once 100mA RISE increase in Power draw is achieved, better stop there, for the MOSFET's are not all perfectly set, but in setting to the CONSERVATIVE side of the voltage turn on threshold, the one or two that turn on in the entire set - that trigger on using the lower levels of power- won't stay latched on AFTER the RF power is REMOVED or turned off...

Okay, I did just exactly the procedure above as stated by "Handy Andy". I had considered this before.
I set the Ammeter up inline with the power supply as above, no RF.....
First, I checked the current as it was since I set the gate voltage at 4 vdc previously.
The current was 1.752 amps at 3.995 (4) vdc.
I turned (V2) the current down to minimum which was .027 ma ......
I added .100ma and then turned the current up to .127 ma using V2 ......
Then I checked the gate voltage at this current draw.
Gate voltage is 3.729 vdc at .127ma current.

The radio is performing just fine with a slight increase in PEP outpower in SSB ....
155 ~ 158 watts PEP output.
Seems to me the radio is performing slightly better with less gate voltage and much less current draw.

 

[Pete Fender]

@linearone

I detect a bit of jealousy, as you only can afford a used Realistic 23 channel Radio Shack special.

 

[linearone]

@linearone

I detect a bit of jealousy, as you only can afford a used Realistic 23 channel Radio Shack special.

Ha! Yeah sure.
Let me tell you something, I have exactly one big black radio left and I don't even use it. I learned my lesson a long time ago. It's amazing that people are still stumbling through the bushes trying to find diamonds on the ground. Big hint they're not there.