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Kevster
| | Posted on Thursday, April 04, 2002 - 4:28 am: | 
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RCI 2950 / Mirage 2950
Frequency Modification
Old Version
Locate the main PCB with Jumpers on it. It is located behind the display board. Find jumper J2. If you clip this jumper, you'll have 26.000-29.700Mhz. If you place the jumper on Pins P1 and P2, you will have 26.000-32.000Mhz. After you "Jump" your radio, you'll need to press the CPU reset button located below J2.
New Version
Real easy to modify! There are a set of Jumpers on the back side of the display board marked "J1" and "J2". One set has a jumper already on it. Remove it and put it on the 2 pins next to it and you'll have 26-29.7mhz. If you jump both set of pins, you'll have 26-32mhz. That's it!
Before you "Peak Out" your radio, you might want to change Q51 from a 2SB754 to a 2SB688 or 2SB817. The 2SB754 is a 60 watt, 7 amp power regulator. The 2SB688 is a 80 watt, 8 amp regulator. The 2SB817 is a 100 watt, 12 amp regulator. The 2SB688 is ok, but the 2SB817 is best.
Modulation
Most people remove Q32, which is the modulation limiter. Yes, this gives you an increase in modulation on AM, but it "garbles" badly on SSB. It also disables VR12 (SSB ALC) and variable power for SSB. I do not recommend this. There are (2) other ways to get great modulation on both AM and SSB.
1) Buy a good after-market powermike.
2) Locate R178 and change to a 3k ohm. Locate R194 and change to a 4.7k ohm.
Locate R281 and change to a 10k ohm resister. Re-adjust VR14 (AMC) for
maxamum forward modulation. If you decide to use a powermike, you'll have have
to change this modification back. If you don't, you'll have overmodulation.
Restoring Power
Place the radio with the display facing you, component side up. Towards the back left corner is a silver Alu board standing up vertically between 3 pins. Pull the board straight out. Solder a piece of 16-22 gauge wire from the middle pin to the positive power on the back side of the power cord. Then solder another wire between the 2 outside pins. Turn RF power knob all the way counterclock wise. Turn mode to AM. Adjust VR15 for 2 watts deadkey. Turn RF power all the way clockwise. Adjust VR13 for maximum dead-key. (about 12-15 watts) Turn mode to LSB. Turn RF knob all the way counterclock wise. Adjust VR16 (SSB low power ALC) for 5-6 watts PEP. Turn RF knob all the way clockwise. Adjust VR12 (SSB high power ALC) for maximum swing. Then turn it back just alittle. You should see a AM swing of about 20-30 watts and 25-40 watts on SSB. If you're "gutsy", you can tune L10, L13, L14, L34, and L46 in AM mode for a few extra watts.
If you want a higher dead-key on AM, parallel 330pf caps across C261, C262, and C270.
This will get you closer to a 20 watt dead-key.
Other Tips
If you change D34and D35 from 1N60s to ECG583, this will improve your AM detection. Distant stations will come in stronger and clearer. If you use ECG583 for D1 and D2, it'll give you a more effective noise blanker.
If you remove or "Clip" D-78 you'll have talkback for your 2950. However it seemed to be alittle distorted. I found that if you replace D-115 with a .0047uF capacitor it'll improve the sound. You might want to install a switch inline so that you can turn it on and off.
For an icrease in receive gain, change Q18 to a 2SC2999. The 2SC2999 transister has higher gain, lower noise characteristics. You will need to re-adjust L8 and L9. The gain will improve with more than 3 to 6 db with the same signal to noise ratio.
To increase audio quality and low power swing, change Q53 from a 2SA1869 to a 2SA473, 2SA1012, or a ECG-NTE 153. (some Ranger/Mirage 2950's already come with a 2SA473) The 2SA473 and 2SA1012 are ok, but the ECG-NTE 153 is best.
Variable Adjustments
VR1- AM "S" Meter VR12- Sideband High Power (ALC)
VR2- Sideband "S" Meter VR13- AM high Power
VR3- Sideband Squelch VR14- Modulation
VR4- AM Squelch VR15- AM Low Power
VR7- Carrier Balance VR16- Sideband Low Power (ALC)
VR8- RF Power Meter VR21- FM Deviation
VR11- Driver Bias
Microphone Pin Placement
1: Ground
2: Modulation
3: TX
4: RX
5: Channel Up
6: Channel Down |
Kb3dcu
| | Posted on Tuesday, August 27, 2002 - 11:37 pm: |
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Where can I get a pictoral or componet id of the 2950 pc board,most of the componets are not marked on the dx, |
Inspector
| | Posted on Sunday, September 01, 2002 - 8:46 am: |
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The parts listed above don't aply to the 2950DX as the parts are labled differently. Parts layout and schematics for the 2950DX can be found for download at RCI's website...You'll need Adoby Acrobat Reader to view the files. |
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