Question about Cobra 148 GTL 120-Channels Base CB Radio

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Can not recieve properly

Ex . i can w/ another radio ,recieve a good carrier from someone.like a 7 w/ a 2 noise level.w/ my radio , i recieve a 2 noise level w/ a 3 1/2 carrier. note; the radio was modified when i purchased it.i sometimes can not hear someone because of this ,when i should?

This is for the 148F the F is for frec. counter , and it is a mobile. It has upper & lowers as well as the side band. It has low receive, and the channels my not be stable. I cannot find info on it. I have not opened it up yet wanted to know where to start FIRST. I have modifacation, info. but NO info on the 148F, much less with the Xtra channel KIT cej0058@yahoo.com

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IN your CB there are 25 tuneing slugs (square matal cans with
ferrite tuneing slugs) if you speaker output is low leavel but still
clear and free of hash the set should be ok , but you will need to tune these slugs with a small jewlers screw driver (WITH GREAT CARE) as the slugs break easy. If you want to email me it will not be a problem ,cheers , DENNIS FLYINGFOX@PEOPLE.NET.AU

Posted on Jun 22, 2008

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Reception is fine, cannot transmit. checked swr's and all below 2. how to check out transmission modulation?


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If you do see that the radio is modulating properly but you cant seem to contact anyone on the air waves, then you need to start looking at your antenna setup. I will not go to deep into this subject because it is so extensive. The antenna system is VERY important. you said you checked SWR and it is below 2. This is a little high...but acceptable. You should really try to get your SWR as close to 1.0 : 1 as you possibly can. Hope this helped. Lost Jeep, Athens GA, 10-7 !!!

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How to adjust frequency on transmit??? Galaxy


hELLO THERE
hERE IS SOME MODIFICATIONS FOR THIS RADIO
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1 Answer

Rushing sound (noise) galaxy 88 HL


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1 Answer

Can not recieve properly


Mounted on the circuit board is a tiny black encased rx/tx
changeover relay. It is almost in the center of the board and one third to the left (facing the controls) and may be etched MRATA.
I would be looking at that. These sets are subject to a lot of problems as they age and can be fixed with a BIG HAMMER!!

CHEERS flyingfox@people.net.au

May 08, 2008 | Cobra 148 GTL 120-Channels Base CB Radio

1 Answer

On rx , i have a low carrier , sometimes cannot hear someone vs another radio


Depends on how it was modded? Were both the TX and RX broadbanded and tetuned?? Possibly poor work..

May 08, 2008 | Cobra 148 GTL 120-Channels Base CB Radio

2 Answers

Making the recieve work better


Hello lugnut, the lack of receiver sensitivity may denote a problem with the RF input amplifier or the IF stages. before attempting to boost the incoming signal I would first want you to check the RF and IF receiver functions first. If there is a problem it would be more advantagous to fix it first. You will need the following equipment 1)schematic (To locate components and test points) 2)digital multimeter (to measure voltages and test points) 3)Radio Frequency (RF) Generator (to provide test and reference signals) 4)IF demodulator probe (to test for proper IF signal amplification along the IF stages) 5)Oscilloscope (To see if audio is being properly reproduced at the audio detector stage) 6) SWR meter(to test the standing wave ratio between (along the coaxial cable path) the antenna and the CB unit. 7)Antenna Dummy load (to emulate the antenna, under FCC law you can not transmitt into the air while testing and repair any transmitter or transceiver). I hope this provides insight into what you will need to work on this problem. These pieces of equipment are needed to properly troubleshoot a CB radio

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