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Tech808
Moderator
Username: Tech808
Post Number: 12363
Registered: 8-2002
| | Posted on Saturday, November 25, 2006 - 7:45 am: | 
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2001 Tech Tips
January:
How about a weather mod for the 121WX & 696F SSB? When you turn the power off on these models, the WX receiver stays on. This is to allow the alert tone to sound and make the owner aware of impending severe weather conditions. Only trouble is, it could wake someone up during the middle of the night. Simply move the 12 VDC wire that powers the "weather board", from the "hot" side of the ON/OFF switch to the cold (or "switched") side. It's just that simple. Now when the radio is turned off, so is the power to the "weather board".
February:
Do you know that you can add talk back to the new DX models of the RCI-2950, 2970 by simply by lifting one end of D67 from the circuit and tape the end to prevent it from shorting out against metal or some other component. With this feature, operators can try different microphones out and hear what they will sound like in actual use. You can even wire in a SPST switch so that you can turn it on & off when desired.
March:
Have you been wanting the new SRA-117 6 pin Echo Mike's to use on the older 2950/70's? Ok, here's how to do it. Simply run a wire from the collector of Q38 to pin 4 of the mike jack. (That was hard wasn't it?) As always, be careful and watchful when soldering. NOTE: Once you have made this modification, do not plug in a regular, stock RCI microphone as it will short out the radio.
April:
Adapting the 4 pin SRA-117A Echo Mike to use with other radios is a simple process. The main requirement to watch for is that you have a "8VDC transmit only" supply available. (Remember that the SRA-117A does not require a battery). Locate a source on the radio that supplies 8VDC on transmit only. Connect a wire to pin 4 on the radio mike jack. With pin 1 at ground, pin 2 for "MIC", and pin 3 for "PTT", the conversion is complete. It is now ready to use. Oh, don't forget to turn on the switch located on the back. NOTE: Once you have made this modification, do not plug in a regular, stock RCI microphone as it will short out the radio.
May:
On the RCI-6900 series (HP & TB Models), some users would like to increase the volume of the talk back. To obtain more audio output from talk back, simply change the value of R200 from 47K ohm to 20k ohm. Now that was simple and easy!
June:
Talk back on a radio allows you to try different mic's to find the one you like the best. Yes, it also lets you hear what you sound like. This month's tip covers how you can add this feature to the TR-396, TR-696F, TR-936 & the TR-966. Simply remove D75 from the board. Simple as that!
July:
The percent modulation of an AM carrier is determined by how much the carrier power varies in amplitude. This is expressed as a "percent of modulation", with 100% being the highest possible undistorted modulation. Beyond 100%, the over modulated RF signal ceases to be a clean sine wave and will produce many harmonics and a higher but misleading wattmeter reading. Over modulation usually results in interference to other radio services above and below the carrier frequency.
August:
We have been receiving calls about using the SRA-117 with the older models of the RCI-2950/70 (pre-DX versions) models, so I thought I'd repeat this modification. It is quick and simple: Install a 22 gauge wire from the collector of Q38 to pin 4 of the mic jack. That's it! This will provide an 8V source to pin 4 each time the unit is keyed. (Remember - this has to be an 8VDC transmit only source.) NOTE: Once you have made this modification, do not plug in a regular, stock RCI microphone as it will short out the radio.
September:
Having comments about that last digit on the RCI-6900 Series flickering? Well, it's not a real problem or something wrong with the radio. It is so simple and easy to take care of, your going to shake your head in disbelief. Simply adjust the clarifier. That's it! It's that simple. You see, the sensing portion of the circuitry detects a frequency beyond the last readout digit and tries to adjust for this reading. If you just move the clarifier a touch, the flickering will stop. Told you it was easy.
October:
To add an SS-64 (Comspec) CTCSS Encoder into the RCI-2950/70/90 (Non-DX Models), perform the following steps:
(a.) Locate Q58 on the main PCB. (b.) Connect the CTCSS output to the base of Q58 with a 100K Ohm resistor in series. (c.) Connect + V of the CTCSS to TX + or to the collector of Q 38. (d.) Install CTCSS's ground to the main PCB ground. (e.) Set the deviation level of the CTCSS to 750 Hz.
For the DX Series, see DX Series CTCSS.
November:
RCI-2980: In some units, you may notice that the frequency will drift when the unit gets warm. This is caused by the "KIA6410S" IC's installed in place of "TA7310P" for IC8 and IC10. To correct this drifting problem, perform the following modifications: a.) Replace C165 with a 270pF ceramic disk capacitor. b.) Replace C190 with a 47pF ceramic disk capacitor. c.) Add a 100pF ceramic disk capacitor between pin 1 of IC9 and GND.
December:
Sometimes, in the older RCI-2990's, if seems that you just need (or want) to have more tone control. It is a very simple step to increase this control. Just change the value of C150 from a .022mF to a .01mF.
2002 Tech Tips
January:
Want to add talk back to the RCI-2985DX & 2995DX? Man, is this one easy! Just remove D67 from the circuit. You can even wire in a SPST switch so that you can turn it on & off when desired. With this feature, operators can try different microphones out and hear what they will sound like in actual use. That's all there is to it. (Don't you just love those tough mods?)
February:
Here's an easy modification to the RCI-2950/70 (non-DX version) so that you can use the SRA-117 Echo Mike: Install a 22 gauge wire from the collector of Q-38 to pin 4 of the mike jack. This will provide an 8V source to pin 4 each time the unit is keyed. NOTE: Once you have made this modification, do not plug in a regular, stock RCI microphone as it will short out the radio.
March:
For those wishing to modify the clarifier on the DX models of the RCI-2900 Series, perform the following modification: (1.) Locate and remove D63 and R115. (2.) Locate connector J28, (a 3-pin connector). (3.) Connect a wire to pin F1 of J28, and attach the other end of the wire to an 8V source. The 8-volts can be obtained from connectors J29, J27 or J26.
April:
To increase T/B level (improving the audio level) on AM, change the value of two resistors.
1. For the RCI-6300 Series: replace R224 with a 56K Ohm (current value=47K), and replace R221 with an 82K Ohm (current value=100K).
2. For the RCI-6900 Series: replace R234 with a 56K Ohm (current value=47K), and replace R232 with an 82K Ohm (current value=100K).
The T/B level is now greatly increased on AM and equal for both AM and FM.
May:
Talk back is a popular subject! Last year I mentioned the quick & simple fix for the TR-396/696/696FSSB. This is a more elaborate version, with the ability to change the audio level. (A). Remove D75. (B). Add Jumper from JP25 to Cathode of D79. (C). If the audio level is not loud enough, replace R221 with 56K Ohm. NOTE: Step C is not really necessary, as the audio level is loud, but to some users it may not be loud enough.
June:
RCI-6900 series: The Problem: SSB power output has a slight delay (about 1~1.5 seconds) on key up when you first speak into the mike. The Cause: Q43 may not turn off fast enough at key up, causing the audio signal to be shorted to ground momentarily. The Solution: reduce the value of R206 from 4.7K to 1.5K.
July:
No modulation in any mode with the RCI-29XX-DX Series? If you are having this problem with the RCI-2950DX, 2970DX or the 2995DX, then you probably have a "leaky" or shorted Q59. Here is how to find out. When trouble shooting no modulation problems, make sure Q43 is off during transmit, in other words - the voltage at Q43 should be 0Vdc during the transmit mode. The voltage at the collector of Q41 should be about 1.5Vdc during transmit. If this voltage is at 4.0Vdc or higher, check Q41 for collector-Emitter short. If Q41 checks good, then Q59 is "leaky" or shorted out. Replace it and all will be well again.
August:
This month's tip is short and sweet. We have received calls about how to increase the volume of the "talk back" on the RCI-2950DX & 2970DX. This one is tough - swap resistors R232 & R234 around. Yeah, that's all there is to it. Piece of cake!
September:
When using earphones on the RCI-2990DX/95DX with the fan kit added, some headphones will pick up motor noise that is fed back into the regulated power supply. This noise can be completely eliminated by installing a 7812 voltage regulator. The voltage regulator provides high isolation and noise rejection from the main power supply. The regulator can be mounted on the aluminum flange next to the main filter caps C196 & C197 (two large caps). See drawing below.
2003 Tech Tips
January:
If you would like to add Talk Back to the RCI-2950/70 - pre DX models, it is just an easy modification. All you have to do is remove D78 from the circuit board. Simple, short and sweet!
February:
Unlocking the RCI-2980 clarifier. 1) Locate and Remove R141(47 ohm) and D38. Save R141 resistor and install it to the solder side of the Main PCB. Connect the resistor (R141) on pin 54 of J106 to pin labeled B+ of J105. 2) Replace resistor R138 with a 2.2k ohm 1/4 watt resistor. The fine adjustment can now adjust transmit & receive frequency to +/- 1 KHz, while the coarse adjustment will shift the transmit & receive frequency to +/- 5 KHz.
RCI 6300 & RCI-6900
RCI-6300FTB Tech Tips: Sometimes, when the BRT/DIM switch is depressed, the frequency will change instead of adjusting the back lighting. If you experience this problem, check if the green wire from the main PCB to J301 of channel selector PCB came loose. This wire may have come off during the process of removing the resistor on the solder side of the main PCB (connected to pin 15 & 16 of IC 5).
RCI-6300FTB & RCI-6900FTB: Supply voltage present at the antenna jack: This problem is a result of a short between the positive side of the terminal lug & the amplifier shield. To prevent damage to your radio, check the antenna jack for voltage before installing your antenna. If 12V or more is measured at the antenna jack, turn the unit off & install an insulator or a piece of electrical tape on the side of PA shield closest to the terminal lug. This will solve the problem. Note: This problem has been corrected on units that were shipped after 10/20/00.
RCI-6300FTB & RCI-6900FTB:New Frequency Display LED's - Due to some early model RCI-6300/6900 display LED's failing in the 1st couple hours of operation, we have switched suppliers which has improved the reliability of the indicator. This should eliminate any display failures that you may have experienced in the past. That's great news for a very popular radio series.
RCI 6300F & RCI-6900F- If you have experienced the frequency readout changing when the radio is keyed, it does not mean the radio has fried or died. It is a simple matter to correct this problem by performing the following steps: (a). Set radio controls as follows: VOL SW to ON; HI/LOW SW to HI; Fr Pool to 1; Mode to AM; +10KHz to OFF; and Clarifier to 12:00 position. (b). The frequency display should read 28.245 MHz. [NOTE: if you do not obtain this reading, do not proceed to the next step. Please refer to the PLL Alignment section in the service manual or on our web site.] (c). Connect a frequency counter to TP3, key the radio, and adjust VR8 to obtain a reading of 17.550 MHz, +/- 20 Hz. (d). Disconnect the frequency counter, and the radio's frequency display should still read 28.245 MHz. You may find, in some cases, simply re-soldering the leads on XTAL X3 can solve the problem.
Hope this Help's,
Lon
Tech808
CEF808
N9CEF
CVC#2 |
Tech808
Moderator
Username: Tech808
Post Number: 13064
Registered: 8-2002
| | Posted on Tuesday, February 20, 2007 - 4:49 pm: |
|
2001 Tech Tips
January:
How about a weather mod for the 121WX & 696F SSB? When you turn the power off on these models, the WX receiver stays on. This is to allow the alert tone to sound and make the owner aware of impending severe weather conditions. Only trouble is, it could wake someone up during the middle of the night. Simply move the 12 VDC wire that powers the "weather board", from the "hot" side of the ON/OFF switch to the cold (or "switched") side. It's just that simple. Now when the radio is turned off, so is the power to the "weather board".
February:
Do you know that you can add talk back to the new DX models of the RCI-2950, 2970 by simply by lifting one end of D67 from the circuit and tape the end to prevent it from shorting out against metal or some other component. With this feature, operators can try different microphones out and hear what they will sound like in actual use. You can even wire in a SPST switch so that you can turn it on & off when desired.
March:
Have you been wanting the new SRA-117 6 pin Echo Mike's to use on the older 2950/70's? Ok, here's how to do it. Simply run a wire from the collector of Q38 to pin 4 of the mike jack. (That was hard wasn't it?) As always, be careful and watchful when soldering. NOTE: Once you have made this modification, do not plug in a regular, stock RCI microphone as it will short out the radio.
April:
Adapting the 4 pin SRA-117A Echo Mike to use with other radios is a simple process. The main requirement to watch for is that you have a "8VDC transmit only" supply available. (Remember that the SRA-117A does not require a battery). Locate a source on the radio that supplies 8VDC on transmit only. Connect a wire to pin 4 on the radio mike jack. With pin 1 at ground, pin 2 for "MIC", and pin 3 for "PTT", the conversion is complete. It is now ready to use. Oh, don't forget to turn on the switch located on the back. NOTE: Once you have made this modification, do not plug in a regular, stock RCI microphone as it will short out the radio.
May:
On the RCI-6900 series (HP & TB Models), some users would like to increase the volume of the talk back. To obtain more audio output from talk back, simply change the value of R200 from 47K ohm to 20k ohm. Now that was simple and easy!
June:
Talk back on a radio allows you to try different mic's to find the one you like the best. Yes, it also lets you hear what you sound like. This month's tip covers how you can add this feature to the TR-396, TR-696F, TR-936 & the TR-966. Simply remove D75 from the board. Simple as that!
July:
The percent modulation of an AM carrier is determined by how much the carrier power varies in amplitude. This is expressed as a "percent of modulation", with 100% being the highest possible undistorted modulation. Beyond 100%, the over modulated RF signal ceases to be a clean sine wave and will produce many harmonics and a higher but misleading wattmeter reading. Over modulation usually results in interference to other radio services above and below the carrier frequency.
August:
We have been receiving calls about using the SRA-117 with the older models of the RCI-2950/70 (pre-DX versions) models, so I thought I'd repeat this modification. It is quick and simple: Install a 22 gauge wire from the collector of Q38 to pin 4 of the mic jack. That's it! This will provide an 8V source to pin 4 each time the unit is keyed. (Remember - this has to be an 8VDC transmit only source.) NOTE: Once you have made this modification, do not plug in a regular, stock RCI microphone as it will short out the radio.
September:
Having comments about that last digit on the RCI-6900 Series flickering? Well, it's not a real problem or something wrong with the radio. It is so simple and easy to take care of, your going to shake your head in disbelief. Simply adjust the clarifier. That's it! It's that simple. You see, the sensing portion of the circuitry detects a frequency beyond the last readout digit and tries to adjust for this reading. If you just move the clarifier a touch, the flickering will stop. Told you it was easy.
October:
To add an SS-64 (Comspec) CTCSS Encoder into the RCI-2950/70/90 (Non-DX Models), perform the following steps:
(a.) Locate Q58 on the main PCB. (b.) Connect the CTCSS output to the base of Q58 with a 100K Ohm resistor in series. (c.) Connect + V of the CTCSS to TX + or to the collector of Q 38. (d.) Install CTCSS's ground to the main PCB ground. (e.) Set the deviation level of the CTCSS to 750 Hz.
For the DX Series, see DX Series CTCSS.
November:
RCI-2980: In some units, you may notice that the frequency will drift when the unit gets warm. This is caused by the "KIA6410S" IC's installed in place of "TA7310P" for IC8 and IC10. To correct this drifting problem, perform the following modifications: a.) Replace C165 with a 270pF ceramic disk capacitor. b.) Replace C190 with a 47pF ceramic disk capacitor. c.) Add a 100pF ceramic disk capacitor between pin 1 of IC9 and GND.
December:
Sometimes, in the older RCI-2990's, if seems that you just need (or want) to have more tone control. It is a very simple step to increase this control. Just change the value of C150 from a .022mF to a .01mF.
2002 Tech Tips
January:
Want to add talk back to the RCI-2985DX & 2995DX? Man, is this one easy! Just remove D67 from the circuit. You can even wire in a SPST switch so that you can turn it on & off when desired. With this feature, operators can try different microphones out and hear what they will sound like in actual use. That's all there is to it. (Don't you just love those tough mods?)
February:
Here's an easy modification to the RCI-2950/70 (non-DX version) so that you can use the SRA-117 Echo Mike: Install a 22 gauge wire from the collector of Q-38 to pin 4 of the mike jack. This will provide an 8V source to pin 4 each time the unit is keyed. NOTE: Once you have made this modification, do not plug in a regular, stock RCI microphone as it will short out the radio.
March:
For those wishing to modify the clarifier on the DX models of the RCI-2900 Series, perform the following modification: (1.) Locate and remove D63 and R115. (2.) Locate connector J28, (a 3-pin connector). (3.) Connect a wire to pin F1 of J28, and attach the other end of the wire to an 8V source. The 8-volts can be obtained from connectors J29, J27 or J26.
April:
To increase T/B level (improving the audio level) on AM, change the value of two resistors.
1. For the RCI-6300 Series: replace R224 with a 56K Ohm (current value=47K), and replace R221 with an 82K Ohm (current value=100K).
2. For the RCI-6900 Series: replace R234 with a 56K Ohm (current value=47K), and replace R232 with an 82K Ohm (current value=100K).
The T/B level is now greatly increased on AM and equal for both AM and FM.
May:
Talk back is a popular subject! Last year I mentioned the quick & simple fix for the TR-396/696/696FSSB. This is a more elaborate version, with the ability to change the audio level. (A). Remove D75. (B). Add Jumper from JP25 to Cathode of D79. (C). If the audio level is not loud enough, replace R221 with 56K Ohm. NOTE: Step C is not really necessary, as the audio level is loud, but to some users it may not be loud enough.
June:
RCI-6900 series: The Problem: SSB power output has a slight delay (about 1~1.5 seconds) on key up when you first speak into the mike. The Cause: Q43 may not turn off fast enough at key up, causing the audio signal to be shorted to ground momentarily. The Solution: reduce the value of R206 from 4.7K to 1.5K.
July:
No modulation in any mode with the RCI-29XX-DX Series? If you are having this problem with the RCI-2950DX, 2970DX or the 2995DX, then you probably have a "leaky" or shorted Q59. Here is how to find out. When trouble shooting no modulation problems, make sure Q43 is off during transmit, in other words - the voltage at Q43 should be 0Vdc during the transmit mode. The voltage at the collector of Q41 should be about 1.5Vdc during transmit. If this voltage is at 4.0Vdc or higher, check Q41 for collector-Emitter short. If Q41 checks good, then Q59 is "leaky" or shorted out. Replace it and all will be well again.
August:
This month's tip is short and sweet. We have received calls about how to increase the volume of the "talk back" on the RCI-2950DX & 2970DX. This one is tough - swap resistors R232 & R234 around. Yeah, that's all there is to it. Piece of cake!
September:
When using earphones on the RCI-2990DX/95DX with the fan kit added, some headphones will pick up motor noise that is fed back into the regulated power supply. This noise can be completely eliminated by installing a 7812 voltage regulator. The voltage regulator provides high isolation and noise rejection from the main power supply. The regulator can be mounted on the aluminum flange next to the main filter caps C196 & C197 (two large caps). See drawing below.
2003 Tech Tips
January:
If you would like to add Talk Back to the RCI-2950/70 - pre DX models, it is just an easy modification. All you have to do is remove D78 from the circuit board. Simple, short and sweet!
February:
Unlocking the RCI-2980 clarifier. 1) Locate and Remove R141(47 ohm) and D38. Save R141 resistor and install it to the solder side of the Main PCB. Connect the resistor (R141) on pin 54 of J106 to pin labeled B+ of J105. 2) Replace resistor R138 with a 2.2k ohm 1/4 watt resistor. The fine adjustment can now adjust transmit & receive frequency to +/- 1 KHz, while the coarse adjustment will shift the transmit & receive frequency to +/- 5 KHz.
RCI 6300 & RCI-6900
RCI-6300FTB Tech Tips: Sometimes, when the BRT/DIM switch is depressed, the frequency will change instead of adjusting the back lighting. If you experience this problem, check if the green wire from the main PCB to J301 of channel selector PCB came loose. This wire may have come off during the process of removing the resistor on the solder side of the main PCB (connected to pin 15 & 16 of IC 5).
RCI-6300FTB & RCI-6900FTB: Supply voltage present at the antenna jack: This problem is a result of a short between the positive side of the terminal lug & the amplifier shield. To prevent damage to your radio, check the antenna jack for voltage before installing your antenna. If 12V or more is measured at the antenna jack, turn the unit off & install an insulator or a piece of electrical tape on the side of PA shield closest to the terminal lug. This will solve the problem. Note: This problem has been corrected on units that were shipped after 10/20/00.
RCI-6300FTB & RCI-6900FTB:New Frequency Display LED's - Due to some early model RCI-6300/6900 display LED's failing in the 1st couple hours of operation, we have switched suppliers which has improved the reliability of the indicator. This should eliminate any display failures that you may have experienced in the past. That's great news for a very popular radio series.
RCI 6300F & RCI-6900F- If you have experienced the frequency readout changing when the radio is keyed, it does not mean the radio has fried or died. It is a simple matter to correct this problem by performing the following steps: (a). Set radio controls as follows: VOL SW to ON; HI/LOW SW to HI; Fr Pool to 1; Mode to AM; +10KHz to OFF; and Clarifier to 12:00 position. (b). The frequency display should read 28.245 MHz. [NOTE: if you do not obtain this reading, do not proceed to the next step. Please refer to the PLL Alignment section in the service manual or on our web site.] (c). Connect a frequency counter to TP3, key the radio, and adjust VR8 to obtain a reading of 17.550 MHz, +/- 20 Hz. (d). Disconnect the frequency counter, and the radio's frequency display should still read 28.245 MHz. You may find, in some cases, simply re-soldering the leads on XTAL X3 can solve the problem.
Hope this Help's,
Lon ~ Tech808 ~ N9CEF
CEF#808 ~ CEF HAM#33 ~ CVC#002
10-10 #61493 ~ 10-10 VP#2688
Tech808@copperelectronics.com
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