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142 gtl audio
- Thread starter stingray
- Start date
cut r104 for modulation.dont expect alot of watts .your working with old technology.probably the most you see is 15 peak on the swing even after the cut.good luck.
don't crank it up all the way cause you'll blow the regulator..it's pretty common for them to blow in those radios
The Regulator issues were caused by poor design which was addressed in a Cobra service bulletin, good idea to make sure the updates are made regardless of Mods. Also very simple to replace the obsolete/no longer made, and expensive regulator with a 7808 and a few other components, about $2.50 in parts.
The radio is capable of over 30 watts on a Bird 43 with Peak reading Kit, while still performing very nicely on SSB.
In stock form the radio is typically rather anemic and disappointing, No mistake though, this radio can kick some serious butt with the right mods done to it. The chassis is also a twin of the Uniden Washington, close relation to the 148GTL, 2000GTL, Grant XL, and a few other 8719 chassis radios.
I bought mine on Fleabay, supposedly working, but typical of many Bay purchases very dead, a few capacitors, full factory specced alignment later, add a few mods to RX, and TX , "The Mod" channel expansion, you have a seriously nice radio. Less than $100 total price.
The radio is an evolution in experimentation for me, my next step is Mosfets.
The radio is capable of over 30 watts on a Bird 43 with Peak reading Kit, while still performing very nicely on SSB.
In stock form the radio is typically rather anemic and disappointing, No mistake though, this radio can kick some serious butt with the right mods done to it. The chassis is also a twin of the Uniden Washington, close relation to the 148GTL, 2000GTL, Grant XL, and a few other 8719 chassis radios.
I bought mine on Fleabay, supposedly working, but typical of many Bay purchases very dead, a few capacitors, full factory specced alignment later, add a few mods to RX, and TX , "The Mod" channel expansion, you have a seriously nice radio. Less than $100 total price.
The radio is an evolution in experimentation for me, my next step is Mosfets.
A simple google search would lead you to everything you need, if your unable to find the info simply asking for it would suffice. Most any competent tech would also be able to provide solutions to these issues. While I do understand what your saying, demanding information which is readily available by using basic internet skills is a bit much. Had it not been the Holidays, and if I had more time I would have Posted a more detailed answer.
Before proceeding with any modifications your radio should be working properly. I would also add most of the following mods entail more than simple clips, and cuts. Simply clipping or removing limiters, and running equipment at inappropriate levels leads to crappy sounding distorted radios rich in harmonics. Do yourself a favor if you don't know what your doing don't do it.
The following mods are a good starting point, there are many more documented, and undocumented improvements, for TX and RX. A bit of research will lead to many updates and improvements. If I get some time I will attempt to make a compilation of these.
STINGRAY, I hope your not trying to get 8-10 watts + of carrier from this radio?
Transmitter Modification Package 2
cobra 142GTL service bulletins - Google Search
MB3756 Sub
Attachments
modifying the 140/142, due to the type of modulation circuit used. I have found that the best over-all sound and performance comes with nothing more than a standard tune-up, with the AMC circuit left intact. However, there are a few mods that will yield better over-all PEP and still keep decent quality sound. Change C90 to a 3.3uf or 4.7uf. RemoveC119, and run a 1000uf cap from negative side of C119's position to the base of TR34, with the positive side of the 1000uf cap going to the base of TR34. Remove R186. ..got this off another site ..any help?