| Author |
Message |
    
Drifter_8291
New member
Username: Drifter_8291
Post Number: 3
Registered: 10-2004
| | Posted on Monday, October 18, 2004 - 8:24 am: | 
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Ok here is one I did to my 148 (new china made) that has a MMB8719 .. (*I AM NO TECH IT WORKED ON MINE BUT DO AT YOUR OWN RISK*)
Cut trace to pin 14 between the cut put a switch when the trace is open (cut) you get ch 37 to 40 27.415 to 27.445..ch 4 is one of the B channels 27.045 ch 8 is 27.095 ch 16 is 27.195...
Pin 12 put a switch to Ground you get
Ch 2 through 13 26.815 to 26.995 ...ch 31 26.835 ch 36 26.885
pin 10 & 11 switched you get Ch 1 through 14
27.605 to 27.765 ....
12pin and ground on and pin 10 and 11 on you get ...ch 2 through 13 27.455 to 27.595 ...ch 31 27.475 ch 36 27.525
...... Hope this helps someone I had looked everywhere and found no mod for this so went about and tried it on my own...
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Drifter_8291
New member
Username: Drifter_8291
Post Number: 4
Registered: 10-2004
| | Posted on Monday, October 18, 2004 - 9:05 am: |
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Pin 12 and ground switch is on ...and pin 10 &11 switch is on...by no means are both these switches to be hooked to each other.. |
Sonoma
Intermediate Member
Username: Sonoma
Post Number: 142
Registered: 11-2001
| | Posted on Saturday, October 23, 2004 - 8:39 pm: |
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what did you do to pin 10 & 11 ,and what do you mean by 10& 11 switched on.
thanks Sonoma |
Drifter_8291
New member
Username: Drifter_8291
Post Number: 5
Registered: 10-2004
| | Posted on Saturday, October 23, 2004 - 10:54 pm: |
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Hook Pin 10 and Pin 11 to a Switch with the switch on meaning (they are connected together) you get Ch 1 through 14 27.605 to 27.765 ...
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Sonoma
Intermediate Member
Username: Sonoma
Post Number: 143
Registered: 11-2001
| | Posted on Monday, October 25, 2004 - 12:00 am: |
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thanks drifter I will try this.should give 26735 and this will be a god send if I get that freq.truckers use lower 19 which is 26735.thanks
Sonoma |
Fusebreaker
Junior Member
Username: Fusebreaker
Post Number: 14
Registered: 3-2004
| | Posted on Friday, May 06, 2005 - 11:32 am: |
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well i found a nice mod for the mb8719 chip that will give you all kinds of channels including 27415-27445
#1 solder a wire from pin #10 to a switch then from switch solder a wire to pin 18
repeat this on pin 11 12 13 14 15 16
when you ground these pins it will change the programming of MB8719
i have no idea what the channel chart is so an external frq counter would be helpful
i would love to hear your guys feedback on this mod |
Yankee
Advanced Member
Username: Yankee
Post Number: 501
Registered: 7-2003
| | Posted on Friday, May 06, 2005 - 1:55 pm: |
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Sonoma: The only way to get the frequency of 26.735.0 MHz. with the MMB8719-MB8719 PLL is to add a second control crystal of the right frequency. The best drop I've ever seen with an open clarifier, and the stock crystal is 26.785.0 MHz., this was on a Cobra 148F-GTL and this was the lowest that the PLL circuit was stable with the stock control crystal. It has been since the late 1980s that I have done any crystal changing so I don't remember the frequency of the dropping crystal, maybe someone on the forum knows the frequency of the dropping crystal.
Hope this is of some help. CEF-357 |
Fusebreaker
Junior Member
Username: Fusebreaker
Post Number: 19
Registered: 3-2004
| | Posted on Wednesday, May 11, 2005 - 5:32 pm: |
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does the cobra 148gtl that copper has for $130 have the mmb8719 the mb8719 or the RCI8719? |
Iluvrf
Member
Username: Iluvrf
Post Number: 51
Registered: 2-2005
| | Posted on Wednesday, May 11, 2005 - 7:29 pm: |
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RCI8719. the old 8719 are not produced anymore |
Fusebreaker
Junior Member
Username: Fusebreaker
Post Number: 21
Registered: 3-2004
| | Posted on Wednesday, May 11, 2005 - 9:13 pm: |
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so i guess that leaves the MMB chip right?
thx |
Bc910
Advanced Member
Username: Bc910
Post Number: 504
Registered: 7-2004
| | Posted on Wednesday, May 11, 2005 - 11:54 pm: |
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In my experience the mmb and mb modify the same. I don't know about the rci though but I would imagine it's the same. But then again, that's all off memory soooooo.
BC |
Yankee
Advanced Member
Username: Yankee
Post Number: 531
Registered: 7-2003
| | Posted on Thursday, May 12, 2005 - 11:42 am: |
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The MB-8719 PLL is still available from many wholesale and retail outlets and I believe they are still being manufactured, also many CB shops have them new and in the junk box. The radios that use the MB-8719 are still in demand and it's not often that an MB-8719 PLL will go bad unless someone blows one. BTW: The MMB-8719 does not completely mod. the same way as The MB-8719. The RCI-8719 is also different. In other words if you have a radio with the MMB-8719, It has to be changed to the MB-8719 for the full conversion. Food for thought with tongue in cheek, a lot of those cheap Yard, garage and flea market sale AM only radios will have a good MB-8719 PLL that can be scarfed to be put in a sideband radio. |
Fusebreaker
Junior Member
Username: Fusebreaker
Post Number: 23
Registered: 3-2004
| | Posted on Thursday, May 12, 2005 - 12:28 pm: |
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thx guys u r a big help i apriciate the help a lot of my friends have 148s and there is dx group on 27.435 i fgot the mod to regain 41-44
simply ground pin 13 |
Bc910
Advanced Member
Username: Bc910
Post Number: 505
Registered: 7-2004
| | Posted on Thursday, May 12, 2005 - 8:58 pm: |
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One of my old MMB's had had the mb mod done and I swear it was identical to the mb freq chart
but then again that was a while ago
BC |
Yankee
Advanced Member
Username: Yankee
Post Number: 534
Registered: 7-2003
| | Posted on Thursday, May 12, 2005 - 9:20 pm: |
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fusebreaker: that was a misstake, the mod. has been corrected under the heading of 8719 PLL coversion question. |
