RCI2995 low output
RCI2995 low output
I acquired a RCI2995 main board number EPT695012B that only has 1 watt of output power. The person I got the radio from had replaced Q60, Q62, and Q66. Thought the problem was in the linear so I unplugged the coax from the linear board that went to the antenna plug and installed it on the main PC board where the output coax ran to the linear and still only had 1 watt carrier and would modulate 1.5 watts. The Receive is fine on the radio. And the PA also works. Not sure where to check since this is a surface mount board. Thank You in advance for any information or suggestions.
Re: RCI2995 low output
First check that the driver and finals are genuine as fakes may note work.
Test the driver and finals to make sure they are ok.
Check PSU known to give out low current.
Later radio are fitted with switch mode PSU and is known to have with the crowbar circuit
If the linear has backfired in to the PA stage check all the caps in the PI filter.
If the fault is in the PA stage, you should be able to find the fault easily with the RF Probe, start at the mixer IC, and work to the finals.
It could just be a dead driver.
Test the driver and finals to make sure they are ok.
Check PSU known to give out low current.
Later radio are fitted with switch mode PSU and is known to have with the crowbar circuit
If the linear has backfired in to the PA stage check all the caps in the PI filter.
If the fault is in the PA stage, you should be able to find the fault easily with the RF Probe, start at the mixer IC, and work to the finals.
It could just be a dead driver.
Rick.
I founded alot of this type of radios with a Corean Driver or final transistor.Take a look in the Driver (2SC2166) and in the Final (2SC2312).If the metal in the transistors is nickel in color you have a piece of Corean S???? transistors.The original Mitsubishi transistors or a good brand of transistors looks grey in color in the metal area.
You can remove the plug of the amp relay for a test the Driver and the Final transistors.This plug is located in the middle of the rear of your radio and has a brown and yellow wires on it.
This type of radio drives the amp with about 2.5 to 4.5 Watts RMS in the AM mode.If you have less than 2 watts (RMS) in the AM mode with the power knob in the high position you have problems in the Driver or in the Final transistor in your radio board,but first you have to check the differents VR adjustments and this includes the AM power VR,the Driver and the Final Bias VRs too.
You can remove the plug of the amp relay for a test the Driver and the Final transistors.This plug is located in the middle of the rear of your radio and has a brown and yellow wires on it.
This type of radio drives the amp with about 2.5 to 4.5 Watts RMS in the AM mode.If you have less than 2 watts (RMS) in the AM mode with the power knob in the high position you have problems in the Driver or in the Final transistor in your radio board,but first you have to check the differents VR adjustments and this includes the AM power VR,the Driver and the Final Bias VRs too.
Rick i changed final and driver and still have same results i also checked PSU and the voltage is staying steady with no drop in volts. Thank you also unit 67 for your help i think i will take this radio to a tech because i don't care much for working on surface mount radios. Thank you both for your time.
Re: RCI2995 low output.
With a RF Probe, see what you have on the Base of the Driver, you should have a least 3 times the voltage at the Collector of the Driver with respect to the Base. Also check you have the 27MHz signal at the driver.
I think you will find that you have no or very little RF drive, at the PA stage, check input to the mixer IC, pre-amp, pre-driver and so no.
You may even find a coil o/c, check both signals at the mixer IC (10.695MHz and 14 to 16MHz).
It is rare that a surface mount component falls.
I think you will find that you have no or very little RF drive, at the PA stage, check input to the mixer IC, pre-amp, pre-driver and so no.
You may even find a coil o/c, check both signals at the mixer IC (10.695MHz and 14 to 16MHz).
It is rare that a surface mount component falls.
Rick.