Hello, I'm having problems with high swr when using 2995. It is at 3.0 plus when the built in amp is on. I am using an Antron antenna which has a match of 1.2 with all other radios connected to it. Asking for any suggestions before I have to send radio in for service. Radio is new and still under warranty but would like to avoid sending back to Ranger for service. Thank you.
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ranger 2995 dxcf swr problems
- Thread starter david laurence
- Start date
How you measure SWR? Internal or external meter?
Most probably you transmit harmonic when amp is on which are outside of measurement range of your meter.
To verify that I would use lowpass filter before smeter.
Mike
Most probably you transmit harmonic when amp is on which are outside of measurement range of your meter.
To verify that I would use lowpass filter before smeter.
Mike
Hello sP5it, I am using separate swr meter after radio. Have never experienced this problem in the many years I have been using cb radios. I agree it must be some harmonics generated by the amplifier. The main board in the radio is EPT695015BR. The amplifier board is EPAC10010D. Could you please recommend a low pass filter to use that might help this problem? Thank you for your response.
If you find the SWR is still high, how comfortable are you in fixing this problem yourself?
I mean, you did ask, but the 2995's internal Amp may be generating those harmonics, but if the output of the Radio - into that amp, is too high, or not tuned right, you can cut to the chase and reduce this spurious output by simply retuning the Transmitter side - it's not hard, but it ain't easy either - it's not for the Feint of Heart.
Some of these radios with their built in amps ran hot right out of the box, so you have to keep your wits about you when you first turn these (Blasted Gosh Darn) things on, or notice problems like what you are seeing - you have to act quickly or you may wind up with it getting toasted and take the radio out with it.
They simply went out biased / adjusted wrong and you'd be able to see the VSWR change by looking at the RF Power on the AM/FM side going down, so would the VSWR REF - as you adjust the RF Power level down - VSWR goes up when the amp gets taxed to take on the task - the spurious output shows up quite plainly as a skyrocketing SWR when you turn up the power.
The antenna is simply reflecting that which it's not tuned for - that spurious output at a frequency the radio makes.
I mean, you did ask, but the 2995's internal Amp may be generating those harmonics, but if the output of the Radio - into that amp, is too high, or not tuned right, you can cut to the chase and reduce this spurious output by simply retuning the Transmitter side - it's not hard, but it ain't easy either - it's not for the Feint of Heart.
Some of these radios with their built in amps ran hot right out of the box, so you have to keep your wits about you when you first turn these (Blasted Gosh Darn) things on, or notice problems like what you are seeing - you have to act quickly or you may wind up with it getting toasted and take the radio out with it.
They simply went out biased / adjusted wrong and you'd be able to see the VSWR change by looking at the RF Power on the AM/FM side going down, so would the VSWR REF - as you adjust the RF Power level down - VSWR goes up when the amp gets taxed to take on the task - the spurious output shows up quite plainly as a skyrocketing SWR when you turn up the power.
The antenna is simply reflecting that which it's not tuned for - that spurious output at a frequency the radio makes.
Thank you Handy Andy for your advice. I have checked the radio with out amplifier in line and have set it up two ways. One with a 4 watt dead key rf power hi and 1 watt dead key rf power low. The second setup was a 2 watt dead key high rf power with 1 watt dead key low rf power. Didn't solve the swr problem when amp is on. The swr is ok without amp. The bias for driver is set at 3.6 volts and final is set at 3.5 volts. SSB APC is at 12.5 volts and AM APC is at 6.0 volts. I don't know if this would be of any help or be a possible clue to what is going on but the swr meter on the radio can be set to calibrate position but does not show any swr readings on radio meter when swr button is pushed to read the meter. Even when swr is at 3.0 it won't show on radio meter. So not sure if amp board is faulty or its a fault on the way back to the front of the radio. Have tried adjusting VR1 on amp board with no results. The gate voltage the mosfets on amp board is 3.5 volts. Set with VR2 on amp board. I would be happy to make necessary adjustments on the radio. I think this is a common board and is similar to a Galaxy 959 radio I have set up. Thank you again for your advice and time.
That's ok, the reason for the SWR meter looking good, is because it's in line BEFORE the amp, and the RF power The Amp sends out the door - so it will always look good to the operator, - but I am glad you see this effort on the EXTERNAL meter you put in, it tells a different story.
The amp board is absorbing - like a Roll of Toilet Paper - all the SWR issues, so that Amp will run hot - and fail quite quickly - if this issue isn't tamed or somehow turned down. The Reflected side of that power not going to the antenna is making the amp work harder as dissipating the heat it already is producing.
So since the SWR internal meter seems to be a little too "dense" to Sense the problem, I'd keep an eye on this condition as well as the power amperage the supply will need to push into the radio to make that Amp work.
Seen several MOSFET types that kill their power supplies because the Gate Voltage and their mA settings are a little too much ON and not enough "OFF" - which too can set a spurious problem or two.
The Reason for the killing power supply, or a good symptom of it, is the "Wink Blink" or just Cut out - go Dark until you turn it off - those moments, the MOSFET or Bipolar, either way, they are on their way out - and will need to be replaced before it kills the supply.
Then the Gate voltages are getting set a bit too high.
The Gates need to have their CURRENT side, that jumper method used, set to 50mA
Voltages are ok, to "set" - but Current is their "Suck point" (SEE: Vacuum Cleaner) Not the Voltage, which is the "turn on" threshold for that gate, but set too high in voltage, they will stay on too long during their cycle.
The benefit of MOSFET, is also their Demise. They have very low-ohmic impedance when they are turned on, it's not like the Bipolar which has a working "Knee" or linear operation. The MOSFET is a nearly perfect switch, very fast on-to off to on times, Bipolar have a Hfe (Gain) values that is Frequency Dependent - MOSFET On Junction Resistance is measured in Siemens or Ohms of Impedance per their AC character - pretty low making them perfect for RF, but too much Gate Voltage, they'll stay on too long and make the power supply fail trying to keep up with the current demands these things, when latched, will pull from the supply rails...
As a side note, many people think of the MOSFET's Rise Times and Fall Times as their switching rates, yes, you can determine the working range of the part this way, But they are not taking into account - the effect the INDUCTANCE (those coils in the strip) as another part of this equation. These coils filter out the bad, but in turn also affect the way the Bipolar used to work, (think Miller Effect or Flywheel - Required Capacitance) MOSFET's see the Inductance and work differently - because of their "Field" effect the Gates have, the Inductance in the Load side of the line determines their actual frequency response.
Too much on time will force the Gate on longer because of the lag behind effect the loading the inductance will impose to force the field to becomes a pulse against the Gate - keeping the Gate threshold "on" for longer periods of time. You don't want that.
if you use the 520 or 13N10's - use 50mA OR LESS to drive these parts before the RF goes into the amp - simply because they will heat up and the Bias to their gates won't track the best to follow along, instead, it will cause them to "Latch" on and stay on longer as they heat up and since they are connected directly to the AM Regulator and the Power Positive Rail, they can suck all the power out of the power supply and literally dim the lights in the Radio and even pop a breaker - from the Power supply trying to catch up as a DC voltage across the MOSFET Drain and Source.
The amp board is absorbing - like a Roll of Toilet Paper - all the SWR issues, so that Amp will run hot - and fail quite quickly - if this issue isn't tamed or somehow turned down. The Reflected side of that power not going to the antenna is making the amp work harder as dissipating the heat it already is producing.
So since the SWR internal meter seems to be a little too "dense" to Sense the problem, I'd keep an eye on this condition as well as the power amperage the supply will need to push into the radio to make that Amp work.
Seen several MOSFET types that kill their power supplies because the Gate Voltage and their mA settings are a little too much ON and not enough "OFF" - which too can set a spurious problem or two.
The Reason for the killing power supply, or a good symptom of it, is the "Wink Blink" or just Cut out - go Dark until you turn it off - those moments, the MOSFET or Bipolar, either way, they are on their way out - and will need to be replaced before it kills the supply.
Then the Gate voltages are getting set a bit too high.
The Gates need to have their CURRENT side, that jumper method used, set to 50mA
Voltages are ok, to "set" - but Current is their "Suck point" (SEE: Vacuum Cleaner) Not the Voltage, which is the "turn on" threshold for that gate, but set too high in voltage, they will stay on too long during their cycle.
The benefit of MOSFET, is also their Demise. They have very low-ohmic impedance when they are turned on, it's not like the Bipolar which has a working "Knee" or linear operation. The MOSFET is a nearly perfect switch, very fast on-to off to on times, Bipolar have a Hfe (Gain) values that is Frequency Dependent - MOSFET On Junction Resistance is measured in Siemens or Ohms of Impedance per their AC character - pretty low making them perfect for RF, but too much Gate Voltage, they'll stay on too long and make the power supply fail trying to keep up with the current demands these things, when latched, will pull from the supply rails...
As a side note, many people think of the MOSFET's Rise Times and Fall Times as their switching rates, yes, you can determine the working range of the part this way, But they are not taking into account - the effect the INDUCTANCE (those coils in the strip) as another part of this equation. These coils filter out the bad, but in turn also affect the way the Bipolar used to work, (think Miller Effect or Flywheel - Required Capacitance) MOSFET's see the Inductance and work differently - because of their "Field" effect the Gates have, the Inductance in the Load side of the line determines their actual frequency response.
Too much on time will force the Gate on longer because of the lag behind effect the loading the inductance will impose to force the field to becomes a pulse against the Gate - keeping the Gate threshold "on" for longer periods of time. You don't want that.
if you use the 520 or 13N10's - use 50mA OR LESS to drive these parts before the RF goes into the amp - simply because they will heat up and the Bias to their gates won't track the best to follow along, instead, it will cause them to "Latch" on and stay on longer as they heat up and since they are connected directly to the AM Regulator and the Power Positive Rail, they can suck all the power out of the power supply and literally dim the lights in the Radio and even pop a breaker - from the Power supply trying to catch up as a DC voltage across the MOSFET Drain and Source.
Greetings, I am currently working on a Ranger 2995dxcf that ate its mosfet board. I am in need of a EPAC10010D board. Does anyone know where I can order one from?
As always, thanks my fellow radioites.
As always, thanks my fellow radioites.
Barkett Electronics
stores.goldeneagleradios.com
Ranger RCI2995 DX Amp Board Assembly Kit / Galaxy DX94HP No Warranty
Wow that's a 4 mosfet board, I don't know why but I had thought that it had a 2x2290 board. I've never owned one so I learned something.Barkett Electronics
Ranger RCI2995 DX Amp Board Assembly Kit / Galaxy DX94HP No Warranty