RCI 2950DX: Review, Expansion & Clarifier Modification
The RCI 2950 has been around for many years. The first radio of this type from Ranger Communications was the RCI 2900. The 2900 radio was a CPU type radio with an analog S/RF meter. Comparing the 2900 to the 2950, the meter was the only redeeming quality of the 2900.
The 2900 radio was a complete failure. There were modifications on top of modifications to attempt to make these radios work. One was so extensive, it required numerous parts and circuitry changes, taking a couple of hours to complete. After all the upgrades, the radio was still not very good.
In fact as soon as the 2950 was released they no longer recommended the upgrade, they suggested radio replacement. I imagine some 2900 owners received a free 2950 as a replacement if they complained loud enough.
Ranger Communications has continued to improve their engineering and manufacturing techniques over the years. They manufacture most of the 10 Meter radios on the market today.
Their factories manufacture radios for many other US based companies including Galaxy. They have been known to copy or clone radios like the President Jackson and Grant, this information is only included to inform, not to praise them for doing so. In fact, the 10 Meter chassis used in all their radios have evolved from that original Uniden design.
The dual final, AM modulator/regulator, mixer, receiver stages are all variations of that original 120 channel Grant radio.
The designs quickly included circuitry to increase bandwidth to cover the increasing frequency range.
Other variations were to adapt for obsolete components as years passed.Now Ranger Communications has improved the 2950 with completely redesigned CPU and main circuit boards.
From the outside, you may think it’s the same old 2950. All the controls and buttons are in the same location as in its predecessor. The face is gray instead of black and of course, it’s labeled 2950DX. Many operators thought the only difference was the dual band coverage.
This wouldn’t have taken a complete redesign; there were Mirage 2950s that covered 24.0000 MHz to 30.0000MHz.
The only difference between the RCI and the Mirage was the CPU. The main board was pretty much the same. However, the real news is that the 2950DX is improved in many areas.
Not too many people are aware of why the 2950 radio was really redesigned. The driving force was Sony discontinuing the PLL chip used in this radio.
The chip was discontinued some years ago. RCI must have made one last large purchase of the chips to keep them going as long as they did.SMT or surface mount technology is used in this new generation Ranger.
Many radio shops haven’t been receptive to the surface mount technology used in these radios. They are more difficult to repair, if not impossible for some shops.
To combat this Ranger changed the warranty period from one year to two years, in order to show their faith in this newer technology. It seems to be working, sales of these radios has increased in recent months.
RCI is using this CPU and main board combo in a number of radios. The 2950DX-30 Watt mobile, 2970DX-150 Watt mobile, 2985DX-30 Watt base station, the 2990DX-150 Watt base station, and I’ve been told the 5054DX 6 Meter mobile.
The board even has provisions for producing an AM/FM only version, which has caused this issue of CB World Informer to run late. This will be explained later in the review.The first look inside is memorable.
This doesn’t look like any of the other RCI HF radios. There is RF shielding on the main PC board for VCO circuits, TX mixer circuit, and RX front end, mixer and initial IF stages.
All the tin shields are punched for adjustment access and are stamped with the adjustment designators. Quite impressive, this hasn’t been done since the late 1970s.
Two radios come to mind that had this level of shielding, the CPI CB radio line and the Stoner PRO-40 SSB rig. These of course were CB radios, but they were top of the line rigs and operated in the sister band of 11 Meters.
A look at the 2950DX schematic revealed a double balanced mixer stage in the receiver. This is found in HF rigs costing many times the price of the radio.
This design is used for better intermodulation rejection. RCI claims other receiver enhancements that improve the receiver sensitivity.
Also revealed, the schematic contains a seven-transistor noise blanker. We’ll put that baby to the test at the shop’s noisy location.The Ranger specification sheet indicates that the meter is capable of reading modulation, no function found to perform this measurement. This is a misprint.
The frequency stability is listed as .001%. If this specification is true, this makes it one of the most frequency-stable 10 Meter radios available.It’s now time for the stock radio bench test. The first results are with the RF power control set to the full power clockwise rotation. The AM and FM output is at 9-Watts.
The AM modulation swing is 22-Watts peak. The sideband power is 27-Watts PEP. Now the output readings with the RF power control in the low power counter-clockwise rotation. The AM/FM power dropped to 1-Watt.
The AM modulation swing is 2.5-Watts PEP. The sideband power dropped to 4 –Watts PEP.Testing the receiver indicated that the sensitivity was quite good on all modes. Even very weak signals on AM and sideband were cleaner than on the old 2950 and on most 10 Meter radios for that mater.
Now satisfied with the sensitivity of the receiver, the selectivity was then checked. My crude method is to crank up the signal generator to full RF output, modulated to 100% with a 1KHz tone. This registers 30 dB on a calibrated “S” meter, or is equivalent to a signal of someone less than a ¼ mile away.
On AM & FM, the radio performed much better than expected. The old 2950 didn’t do very well with this test. Sideband however, displayed a signal of approximately 4 bars on the LCD meter 200KHz on ether side of the center frequency before the strength started to decrease.
This is to say, if someone was coming in at 30dB on channel 20, the signal from that transmission would still be received at four bars on channels 1 and 40.Being puzzled and thinking this must be a defective radio; a second 2950DX was pulled from its box and tested. The results were identical.
To confirm the test equipment was operating properly, two radios were tested, a Uniden Grant and a Galaxy 88. Both radios tested fine. Now the story gets more interesting, a call to JR at Ranger service didn’t resolve the issue. JR said they could not reproduce the results at their service lab. He went further to say the ARRL tested the RCI 2970DX and found no problem of this type.
As concern grew, a decision to contact the author of the RCI 2970DX review in QST magazine was made. Contacting Wayne Irwin was a pleasant experience. After explaining that he wasn’t responsible for the lab testing, he offered to find what he could and reply.
Wayne agreed the transmitter unwanted sideband figure of 39dB (50dB is a minimum figure one would expect) could be due to the design issue findings. Here is the response from Wayne:
The E-mail states the problem wasn’t apparent in their lab tests, but they don’t deny a potential problem. Looking at the receiver test results, a test for selectivity was done on FM, but no SSB selectivity test results were published.
The assumption may have been made, that if FM were tight SSB would be better.
I wrongly made this assumption myself on all the radios tested prior to this article. I will cover what I feel is a design flaw and what is needed to correct the potential problem in the next article, titled Image Rejection Modification.
I have also tried to contact Gordon West about his findings while reviewing the RCI 2970DX for Popular Communications.
I haven’t received a response yet.Continuing the review with a modified IF stage showed the 2950DX to achieve excellent results on the sideband selectivity test. Compared to other 10 Meter radios, the RCI 2950DX performance was outstanding, and this one covers 24 MHz to 32 Mhz. Until now, radios selectivity suffered more as frequency coverage increased.
The RF power control works well and tracks well with the modulation and output limiter circuits very well as long as the limiter isn’t removed altogether. This radio sounds so good, I don’t recommend eliminating the limiter circuit.
Great results can be had by turning up the SSB power, SSB limits, and AM modulation controls up fully. If you were looking for a radio to make a lot of noise with, many other radios would be a better choice.
This is a great all mode radio, for operator’s who are looking for good clean communications, don’t spoil it with the old tricks to get every last milli-watt out of it. Square wave audio isn’t becoming of this one.
Testing the receiver on the air dramatically demonstrated the difference between the RCI 2950DX and its predecessor. All modes sounded clear and crisp. Even very weak signals were easy to understand.
Single sideband is especially natural sounding, with greater sensitivity and lower noise than any other 10 Meter radios I’ve tested to date. The only fault with the radio is the meter. It flickers on AM and SSB not holding long enough to achieve accurate readings. T
his was corrected by the addition of a 4.7uf capacitor connecting the positive lead to the MT signal or the band side of D14 and the negative side of the capacitor to ground. This only effects the meter portion of the radio, both incoming signal and outgoing powerFrequency stability is super.
The radio tested drifted only 30 Hz from power on to one hour of running. The clarifier is very easy to tune whether it’s unlocked or not.The display is unchanged with its large six-digit frequency readout.
The backlighting has changed from amber to green. This green lighting is very evenly distributed and it almost appears to be of the electro luminescent type used in the Cherokee and Cobra faceplates, but it’s not.
The schematic indicates two incandescent lamps, but the lamps are in a sealed unit and an ohmmeter reading leads me to believe there may be banks of LED in the light panel.
I hope this to be true, LEDs will last much longer.
If you’re familiar with the old 2950, you’ll know how all the functions work, they haven’t changed much. The following figure indicates the front panel controls, switches, and indicators.
Controls Of The RCI 2950DX
- FREQUENCY SELECTOR: This control is used to select a desired transmit and receive frequency.
- RF POWER CONTROL: This control allows the user to adjust RF power output.
- MIC GAIN CONTROL: Adjusts the microphone gain in the transmit and PA modes. This controls the gain to the extent that full talk power is available several inches away from the microphone. In the Public Address (PA) mode, the control functions as the volume control.
- ON/OFF VOLUME CONTROL This knob controls the volume and the power to the radio. To turn the radio on, rotate knob clockwise. Turning the knob further will increase the volume of the receiver.
- SQUELCH CONTROL: This switch is used to eliminate background noise being heard through the receiver which can be disturbing when no transmissions are being received. To use this feature, turn the control fully counterclockwise and then turn clockwise slowly until the background noise is just eliminate. Further clockwise rotation will increase the threshold level, which a signal must overcome in order to be heard. Only very strong signals will be heard at a maximum clockwise setting.
- RF GAIN CONTROL This control is used to reduce the gain of the RF receiver amplifier under strong signal conditions.
- CLARIFIER CONTROL Allows tuning of the receive frequency above or below the assigned frequency by up to 500 Hz. Although this control is intended primarily to tune in SSB/CW signals, it may be used to optimize AM/FM signals.
- MODE (FM/AM/USB/LSB/CW/PA) SWITCH: This switch allows you to select one of the following operating modes: FM/AM/USB/LSB/CW/PA.
- NB/ANL BUTTON (NB/ANL): In the NB/ANL position, the RF Noise Blanker and Automatic Noise Limiter in the audio circuits are also activated. The Noise Blanker is very effective in eliminating repetitive impulse noise such as ignition interference.
- ROGER BEEP BUTTON (R.BEEP): In the Roger Beep position, the radio transmits an audio tone at the end of your transmission to indicate that transmission has ended. As a courtesy to others, use the Roger Beep only when necessary.
- SPLIT BUTTON (SPLIT): This control activates the offset frequency function. It causes the transmit frequency to be offset either above or below the receive frequency by a user programmable amount to allow operation of an FM Repeater.
- PROGRAM BUTTON (PRG): This button is used to program operating or scanning frequencies into memory. See the OPERATION section of the manual for further details.
- MANUAL BUTTON (MAN): This is used to return the unit to manual mode.
- SHIFT BUTTON (SHF): This is used to select 100 Hz, 1 KHz, 1O KHz, 100 KHz or 1 MHz frequency steps.
- DIM BUTTON (DIM): This button adjusts the display backlighting in four different steps to best match the ambient light.
- SWR BUTTON (SWR): This control is used to check SWR.
- SCAN BUTTON (SCAN): This is used to scan frequencies in each band segment. The OPERATION segment of the user manual provides detailed information on using the SCAN control.
- MEMORY BUTTON (MEM): This button is used to program memory channels. Detailed information on how to use this control is provided in the OPERATION section of the user manual.
- ENTER BUTTON (ENT): This is used to program frequencies in memory. See the OPERATION section of this manual for more information on using this control.
- LOCK BUTTON (LOCK): This button is used to lock a selected frequency. Press it to activate the switch. In this position, it disables the Frequency Selector Control, up/down buttons on the front control panel and remote up/down buttons on the microphone. Repressing the switch will unlock the frequency.
- UP/DOWN SELECTOR: These buttons are used in conjunction with the shift key to move the frequency upward or downward to select a desired frequency.
- METER: This meter indicates received signal strength, transmitter RF output power and SWR level.
- LCD DISPLAY: The LCD displays the frequency selected, functions and memory channel.
- MIC JACK: Accepts 6 pin female connector with a type Philmore T616C or Calrad 30445 style connector.
1. Memory ChannelsPress PRG, then press MEM, then enter frequency, then press ENT. To select any of the 0-9 memories, press MEM each time to step to the next desired memory channel.
2. Scan RangePress PRG, then press SCAN (SCAN+ will appear on the display), then enter frequency for the high scan limit, then press ENT, then press SCAN (SCAN- will appear on the display), then enter the frequency for the low scan limit, then press ENT. Unlike the 2950, setting the scan limit doesn’t limit the frequency operation outside the scan mode, even though the DX user manual states it will.
3. Frequency SplitPress PRG, then press SPLIT, enter the desired frequency split, then press ENT.
Memory channels are accessed by pressing the MEM button. Each time the MEM button is pressed, the memory advances one channel. To exit the memory channels, press the MAN button.Two scan options are available, memory scan and frequency scan.
Frequency scan will scan between the high and low limits programmed. If no limits are programmed, the radio will scan the entire frequency range of the radio. Squelching the radio starts the radio scanning.
Once a signal breaks through the squelch, the radio pauses until the signal no longer breaks the squelch for about a second.
Pressing the SCAN button once indicates a SCAN(+) on the display and causes the radio to scan up. Pressing the SCAN button again indicates SCAN(-) on the display and causes the radio to scan down.The split frequency is selected by pressing the SPLIT button.
Pressing the SPLIT button once indicates SPLIT(+) on the display and causes the amount of frequency split programmed to be added to the receiver frequency during transmission.
Pressing the SPLIT button again indicates SPLIT(-) on the display and causes the amount of frequency split programmed to be subtracted from the receiver frequency.
Pressing the SPLIT button a third time shuts off the split feature.If you’ve never used a 2950 before, it comes with a user manual that Wayne from QST correctly regards as adequate that will help you master the functions.
If you liked the 2950, you’ll love the 2950DX. This is a great dual band radio for the money; I recommend it for anyone that takes radio seriously. If you weren’t impressed with the old 2950, like myself,
I think you’ll have a different outlook on Ranger Communications Inc. after trying one of these!
RCI 2950DX Component Layout
RCI 2950DX Image Rejection Modification
As noted in the review, an anomaly, not found in other radios, was found in two of the RCI 2950DX tested. Further test determined signals outside the passband of the 10.965 crystal filter were indeed getting through or around this filter. All the components and every circuit trace was followed per the schematic diagram.
No component failures were found. In addition, no visible faults were found with the circuit board following the schematic diagram. However, the circuit board diagram indicated a resistor R325 location under FL3, the 10.965 crystal filter.Removing FL3 was more difficult than anticipated due to the double sided circuit board. Once removed, the R325 location was revealed and empty.
Testing the radio with the filter removed showed the same image problem was encountered. Probing the area of R325 with test equipment indicated the sensitivity of the circuit. The closer test probes got to the pads of this resistor, the higher the signal strength on the radio LCD meter.
This concluded the remedy needed.As explained in the RCI 2950DX review, Ranger Communications could not duplicate this problem. This means they do not acknowledge this problem. No doubt this will not be covered under warranty. In addition, if not properly done, it may indeed void the warranty.
The following modification portion of this article describes and illustrates how to perform the modification, but due to the double sided printed circuit board, it is very difficult to remove the FL3 crystal filter without damaging the circuit board!
THE FOLLOWING PROCEEDURE SHOULD ONLY BE DONE BY A QUALIFIED TECHNICIAN WITH EXCELLENT SOLDERING SKILLS!!! CB World Informer or the author cannot be held responsible for any damage or loss of warranty!
Now that I’ve scared the the stuffing’s out of you, lets get back to the mod so you understand what was done to the test radio.. As mentioned above, this is a double sided circuit board.
The heavy ground plane is where the most difficulty will be found. It requires a great deal of heat to melt the solder on the other side of the board in order to remove it with an extraction tool. A high wattage soldering iron used for only as long as necessary should be used. That’s where the experience comes in.
If you leave the iron on too long the circuit board will burn and the traces will lift of the board. Even if it’s patched up, if noticed during a warranty repair, RCI may deem the radio out of warranty and then you’re SOL. In addition, if there is still solder holding the filter and you pull it out only to find it’s missing a pin or two, ditto!
Please leave this one to the professionals. All radios that incorporate this main circuit board have been and will continue to be modified by Bob’s CB & Wireless prior to sale at no additional charge. If you own a RCI 2950DX, 2970DX, 2985DX, 2990DX, Bob’s CB & Wireless offers this modification at $25.00.
As described above, the crystal filter FL3 must be removed. There are two traces from R325, one connects to the input of the filter and the other connects to the output of the filter. Both traces can be pealed up using a xacto-knife. Remove the resistor pads and traces back to the filter connections cutting the traces off at the crystal filter pads.
See diagram and photos below.
FL3 Section Of Circuit Board Diagram
FL3 Component Side Of Circuit Board.
FL3 Removed From Circuit Board.
R325 Traces Removed From Circuit Board
RCI 2950DX Expansion And Clarifier Modification
The RCI 2950DX is capable of covering 24.0000 MHz to 32.0000 MHz with the addition of a small circuit board provided by an undisclosed third party. It must be mentioned that radios from some Ham Radio only dealers cannot be converted. The prices are lower on these radios, be careful, you may be buying something you don’t want. The conversion key board plugs into the front panel board or in some earlier radios into a flying lead header connector. That’s it.
The clarifier is quite simple also. Remove D63 located near VR8 TX Frequency pot. At J28 cut the black wire close to the connector and solder it to point marked 8V on J29. See the photos below.
D63 Location – https://www.rivud.com/images/0109/2950dx_d63.jpg
D63 Removed And Black Wire Cut – https://www.rivud.com/images/0109/2950dx_d63_removed.jpg
Black Wire Connection – https://www.rivud.com/images/0109/2950dx_connect_wire.jpg
Removing D63 disconnects the TX Frequency potentiometer from the clarifier circuit. Cutting the black wire removes the receiver 8 volts from the clarifier potentiometer. And connecting the black wire to J29 8V applies 8 volts constant to the clarifier potentiometer.