need help from the 148gtl experts.??

[1iwilly]

hello to all
my 148 has aproblem that with mic gain off no mudulation or even with mod it show a weird reading like a forward spike
the radio no matter what dead key you set it too when you key the mic the watts instead of going directly to where the dead is set to it goes a few watts over then comes back down to the set dead key. when talikng on the radio after you say your last word and still have the mic key the watts goes forward then back down to dead key setting all the amc limiters are intact even if i clip r131 no change take out tr 24 no change put tr24 back in take out tr 26 no change any one ever seen or heard of this kind of problem even when i turn vr 7 mod trimmer it does nothing to my audio increase or decrease check trimmer with ohm meter it read good.

 

[loosecannon]

the only time ive seen this happen is when doing this mod:

"RemoveC174, and run a 1000uf cap from negative side of C174's position to the base of TR41, with the positive side of the 1000uf cap going to the base of TR41. Reset the AMC level for 100% modulation. "

check around the rear right side of the chassis near TR41 (mounted to the chassis wall) and see if C174 has been changed in value (should be a 1uF i think) or if its been removed and the above mod done.

LC

 

[Moleculo]

I had one that did the same thing and it had that same mod. I never associated the two, but it does make sense.

 

[1iwilly]

I had one that did the same thing and it had that same mod. I never associated the two, but it does make sense.

i found the problem the guy that had it before me sent it out to a cb tech and from what i can see he did a npc mod diode resitor from 1 let of tr41 to another spot radio swing to 7 watts on a bird but that upward surge i didn't like i took it off now radio is back to normal except that from 2 watts dead key it only swings to 5 1/2 on a bird ssb does 15 bird watts but i want am to be a little better any ideas or suggestion and still have a clean sounding radio

 

[jazzsinger]

if your measuring 5 1/2 watts forward swing on an avg reading meter,then chances are amc has been disabled,it should only swing to 3w on an avg meter with 100% modulation.

if your measuring 5 1/2 watts swing on a peak reading meter chances are the modulation isn't set high enough for 100% modulation,100% modulation on a 2w carrier should swing 7.8w.

 

[TonyV225]

Ive seen a few do that with those crazy clipping type mods I was baffled the first time I seen that happen to a someones radio and it wasnt a 148 that I seen doit the first time.