| Author |
Message |
    
Jake
| | Posted on Tuesday, February 26, 2002 - 11:48 pm: | 
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First of all does anyone have a schematic for this radio? it would help. I just got it used and it's supposed to have all channels however you can receive the same person on several channels in sucession channels 1-6 are inop and i dont get all 40 channels, it has two switches on the back for the extra channels can some one give me some help oh it has a D858 chip in it if this will help thanks Jake |
Tech181
| | Posted on Wednesday, February 27, 2002 - 12:10 am: |
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Jake,
The UPD858C PLL is non-modifiable by itself. You need an add-on board to do it. More than likely there is a problem with that. E-Mail me...
Steve
Tech181
Tech181@copperelectronics.com |
307
| | Posted on Wednesday, February 27, 2002 - 12:43 pm: |
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Either that or the PLL is out of lock. When this happens you will receive the same on many channels.
307 |
Yankee
| | Posted on Monday, February 02, 2004 - 11:41 pm: |
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Looking for the chnl mod that was used years ago on the President Washington or Cobra 139XLR W/UPD858 PLL, useing 3 switchs as follows: switch one, single pole single throw = switch two double pole double throw = switch three double pole double throw center off. hope someone also has a channel chart for this mod. Thank you, Yankee |
Yankee
| | Posted on Monday, February 02, 2004 - 11:41 pm: |
|
Looking for the chnl mod that was used years ago on the President Washington or Cobra 139XLR W/UPD858 PLL, useing 3 switchs as follows: switch one, single pole single throw = switch two double pole double throw = switch three double pole double throw center off. hope someone also has a channel chart for this mod. Thank you, Yankee |
Yankee
| | Posted on Tuesday, February 03, 2004 - 3:24 am: |
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Need 10 kc mod. for Washington W/UPD858 PLL, with the standard mods I've found the rig can't do 27.545.00 have a group of friends that run this frequency, somewhere in my memory it seems that pin 13 had something to do with 10kc, but it's been to many years since I've had one of these rigs. Thanks to all of you, Yankee |
Kc0gxz
| | Posted on Thursday, February 05, 2004 - 4:20 am: |
|
Yankee
I used to convert these radios back in the 70s until the FCC outlawed the 858 chip. It's still the best chip ever put into a CB radio. Nothing like it since then. Todays 8719 chip is a joke when compared to the 858.
You are right. There is a chip modification for a 10Khz shift on the old 858 chassis and you were also correct about it being off of pin 13. You have a good memory. I did some heavy-duty digging in my archives to find this one. Here it is.
1- Cut the track that goes to pin 13.
2- Put a 4.7 K Ohm 1/4 watt resistor across the cut.
3- Now install a SPDT (center off) toggle switch.
4- Wire the top pin on the switch to ground.
5- Wire the middle pin on the switch to pin 13 on the PLL.
6- And last, wire the bottom pin on the switch to a constant supply voltage that is the SAME AS THE PLL PIN CONTROL VOLTAGE.
--------------------------------------------------
Another way of getting more down "slide" was by installing 3 super diodes in place of D-45, D-43 and D-41. And to get more upward slide, you could remove capacitor trimmer #4, 5 and 6. But doing those stupid slider mods "I DO NOT RECOMEND" unless you don't mind having a center slot for each mode!!!
The most slide I would ever put on ANY clarifier control was 5.5-6Khz down. Any more than that, you are guarenteed to see the transmit and receive frequency start to split. The reason why is because the clarifier control is a varible resistor. It only varies voltage. Back in the early days of sideband CBs, they used a variable capacitor. A transmit and receive frequency couldn't split with that arangement since your varying the capacitance of a crystal.
Anyway, I hope I was able to help you. Good luck.
Jeff, kc0gxz. |
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