Lester's Custom Truck Shop
United States
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Tech Notes will be posted here.
NOTE: ON ALL KITS, RADIO MUST BE IN ORIGINAL CHANNEL CONFIGURATION. ALL CHANNEL MODS MUST BE REMOVED AND COMPONENTS RETURNED TO ORIGINAL CONDITION.
Clarifier mods are OK.
CHANNEL SELECTOR OBSERVATIONS
As you are now aware, we're using the channel selector instead of an encoder with our new L4.D5 board. This makes installation a lot simpler. However, channel selector switches are sloppy when it comes to switching contacts. Most channel selector switches "break before make". What this means is that there is no smooth transition from one position to the next. It's a phenomenon mistakenly referred to as "contact bounce". However in this case the contacts are actually making and breaking contact. Not bouncing like relay contacts. Instead of the switch going straight from a count of say 5 to 6, it's more like 5 to 7 to 25 to 18 to 12 to 6" as the contacts make and break. Radio manufacturers compensate for this by muting the radio audio between channels. So what we've done is write code that has the processor wait until the contacts have settled. It looks at the input over a specific time period to see if the value is still changing. If it is constant for more than a given period it then measures the input. This all happens in a minute period of time less than one tenth of a second. While this works 99% of the time, there is still that 1% where it doesn't. What this means to you is that it may take 2 clicks sometimes to go up or down 1 channel. A small inconvenience considering the benefits.
A NOTE ABOUT PLL IC'S
The RCI8719-97 is a 7 bit device, but the internals of the IC do not allow it to control the VCO as well as a -99. I recommend you replace it with an RCI8719-99 or MMB8719 and change the crystal. You’ll be much happier with the results. Also, remember if you do this, do not connect A14 to +5 volts.
Some of the newer radios are coming with the MMB8719 in them. They are different from the -99. Be sure to adjust VR1 as noted in the instructions.
Also, I've noticed that techs sometimes try to adjust VR1 by watching the counter in the radio. While this will get the radio on frequency, the VCO may not perform correctly. Be sure to adjust it using a DVM. VR1 is very touchy at the specified voltages. You will see this in the DVM reading, but not in the counter.
UNIVERSAL KIT NOTES
-For the 919, 929 and 979, A13 must be pulled high (+5volts).
-For the 8719-97 PLL radio's, A14-only must be pulled high (+5volts).
-In the 919, 929, 979, a pull down resistor is required on PLL pin 10, P6. Add a 10k ohm resistor between pin 10 and ground.
COBRA KIT NOTES
COBRA KITS ARE NOT PLUG AND PLAY
- In the Cobra's, you must replace the MB8734 PLL with an 8719 PLL for the board to work. (For any channel mod to work for that matter.)
When installing the new harness in Cobras or Cobra type radios, be sure the connector side with the >> marks is toward the outside of the board.
LesComm TM
3-Band kits are bands B-C-D
Bands A and E included in the 192 channel upgrade.
Most 8719 Galaxy's using the stock crystal.
Band
A - 26.695 - 27.135
B - 27.145 - 27.585
C - 27.595 - 28.035
D - 28.045 - 28.485
E - 28.495 - 28.605 on ch 1-10
Cobra 8719 = 26.815 thru 28.725 (192 Ch upgrade)
LesComm TM
Ranger, Galaxy & Cobra radio's using the crystal in the kit;
Band
A - 26.065 - 26.505
B - 26.515 - 26.955
C - 26.965 - 27.405
D - 27.415 - 27.855
E - 27.865 - 27.975 on ch 1-10
LesComm TM
Power out improvement of Uniden made SSB CB radios that use the MB8719/8734 PLL IC
LesComm TM
As the title implies, the following instructions will improve the output power of these radios over a broader range of frequencies than they originally came. Normally, when these radios are modified to cover more frequencies, the farther away from the original 40 you get, the more the power drops off. After making the following changes, you should be able to balance the power from top to bottom at almost the standard level as it was on the normal 40.
LesComm TM
Refer to the chart below.
LesComm TM
Model | Cap1 | Cap2 | Res1 | Res2 | Adj |
142GTL | C160 | C159 | R155 | R154 | L28 & L29 |
Washington | C160 | C159 | R155 | R154 | L28 & L29 |
TRC-490 | C160 | C159 | R155 | R154 | L28 & L29 |
148GTL | C163 | C161 | R184 | R185 | L46 & L45 |
2000GTL | C163 | C161 | R184 | R185 | L46 & L45 |
Grant | C163 | C161 | R184 | R185 | L46 & L45 |
Madison | C163 | C161 | R184 | R185 | L46 & L45 |
LesComm TM
What we have done is widen the tuning peak between the coils by increasing capacitance and lowering Q.
The resistor changes increase the bias of the pre-driver transistor to the final stages for more drive without distortion.
Be aware that on some radio installations, if feedback occurs after this mod, you may need to reinstall C159/C161. Only change the value to a 47pf. Increase this value in steps of ~50pf to the original value of 330pf if necessary.
LesComm TM
Intellectual Property Rights Owner Lester's Custom Truck Shop
Intellectual Property
All Intellectual Property, as defined below, owned by or which is otherwise the property of LesComm or its respective suppliers relating to the LesComm kits, including but not limited to, accessories, parts, or software relating there to (the“Expa Kit System”), is proprietary to LesComm and protected under federal laws, state laws, and international treaty provisions. Intellectual Property includes, but is not limited to, inventions (patentable or unpatentable), patents, trade secrets, copyrights, software, computer programs, and related documentation and other works of authorship. You may not infringe or otherwise violate the rights secured by the Intellectual Property. Moreover, you agree that you will not (and will not attempt to) modify, prepare derivative works of, reverse engineer, decompile, disassemble, or otherwise attempt to create source code from the software. No title to or ownership in the Intellectual Property is transferred to you. All applicable rights of the Intellectual Property shall remain with LesComm and its suppliers.
**Kit installation instructions may be used and printed by those actually installing a LesComm kit.
NOTE; ONCE INSTALLED A LESCOMM KIT CANNOT BE RETURNED. However, all LesComm kits come with a lifetime warranty. We will repair or replace the kit at our discretion. Simply return the kit to us. Kit failure due to incorrect installation is not covered.
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Lester's Custom Truck Shop
United States
Webmaste