Cobra 148/148F *RCI made* electrical mod - side mic "Malaysia"
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- Опубліковано 27 лис 2024
- This is a quick tutorial on how to modify a Ranger built Cobra 148 GTL or 148F GTL radio to not warble on sideband once you take it past stock power. These radios are known for this warble, and the fix is amazingly easy. If you have a side mic 148GTL or 148F GTL that says "Made in Malaysia" or "Made In The Malaysia" on the back, you're going to want to watch this.
Some helpful information about these radios written from an autistic INTJ perspective available on my old Facebook page:
/ 3977859315574912
Whats even more strange is that trace on the RCI board is already there, even the spot for the jumper, and it's not being used. Thanks again buddy.
Just the usual, make sure all the solder joints are tight and whatnot. If you want to get more channels than the stock ones, you will need to remove the resistor that feeds pin 9 of the PLL, install a shunt in its place, and replace the PLL with an MB8719. The RCI8719 is a 5 volt chip of dubious design (it works on 40 channels but it's no good for modding), the resistor drops the 8 volt input down to 5 v for the RCI chip, it must be shunted for the MB8719 which is an 8 volt part.
The shunt is any piece of wire that can fit in the provision for J44. I used a lead from a resistor.
The RCI radios are okay once you get past these little design 'issues'. The Taiwan / Philippine 148s are the ones to have, but the only "F" model is going to be RCI made (Malaysia).
Gotcha. The instructions for the Uniden models will work with these as well, in regards to tune up / alignment instruction.
I added a link to my facebook page (this should be set to Public although you'll likely have to sign in to see it) with some more info on these radios.
How do adjust the lsb off frecuency
@@vatoperro1370 You need a frequency counter hooked to TP1, set radio to channel 1, center the clarifier (Voice Lock) and adjust L23 (AM) to 34.7650MHz, L22 (LSB) to 34.7635MHz and L59 (USB) to 34.7665MHz. .0015MHz split between USB, AM and LSB. Don't key the radio while you do this.
Yes, it will help on AM too, as it will stabilize the radio. A voltage drop over the PLL is never a good thing, no matter what mode you operate.
Why they decided to change the original design and draw everything through that choke is beyond me - this mod removes that 'deviation'.
Im not really concerned with extra channels, would just like to do the power and modulation mods, good alignment and let it eat, just having trouble finding any tune up/ alignment info on the malaysia made version.
mine is not the "f" model, just the standard 148, but it is an RCI made unit... is this mod nesessary for AM ? I dont really use USB/LSB, seems this mod would help the radio over all... thanks for your help.
silicon can you tell me what Pcb board number the 148 f uses, or what other radio can replace it directly. I have a 148f here that's missing the mic jack. thanks
+birdman3931ny The PCB in the 148F will be the EPT0148xx board as it is a Ranger product. The schematic for the radio is the same as the older Uniden radios, with the exception of the power issue that this video addresses, along with added circuitry for the frequency counter. If you obtain the SAMS schematic for the original 148 (SAMS CB Photofact 249), you can use that for your mic jack.
+silicon212 thank you
+silicon212 sorry this number you provided is the mic jack number?
No, main board number, didn't see anything specific. The number is EPT014840Z.
Thanks
Is there anything else that needs to be done to this unit?
Hey, I clicked on the link provided for your facebook page but it says that it's not there or not available, something like that. I just got this 148 on ebay and it only has the extra channels for lower side and I want to get it fixed to where it has the uppers. Back like 20 to 25 years ago when I was really into the side band cb's it was always the uppers that was side band and the 148 I had then was rock solid and I was hooked on side band and 148s. Anyway, I wanted to know how to do this or where I could get it done but I am having no luck, could you help me out?
I just noticed this now, never got a notification on it. Try this link: facebook.com/notes/458269814190483/
what did you use for the shunt? was it just a jumper? diode? just curious, i have a rci made 148, several people have told me the Malaysia version is the one to have, starting to wonder if its true, lol.