need help from the 148 gtl experts.???

[1iwilly]

Radio Make and Model: cobra 148 gtl
PCB Number:philly made 1993
PLL Number:rci 8719

i got this radio a while ago it has low modulation when all the limiter are intact radio dead keys 2watts swings to 3 1/2 if i cut r131 then it swings to 8 watts on a bird
i try the 1k resistor to middle leg of tr24 i try tr26 too no luck i've change tr41 upgrade one tr 42. also ssb is fine no modulation problem only on am
i even change tr 23,tr24,tr24,tr26 no luck i also change r124,r126 to 4.7k and r131 to 4.7k no luck. thanks

[lbcomms]

You'll get more chance of a reply if:

1) You don't try to put lots of sentences into one. Punctuation, paragraphs, and correct capitalisation make things much easier to read for someone to help you.

2) Do a bit of basic research first. Try Google.

3) Learn a bit about what you are trying to archive. How are you measuring your "low modulation"? Have a look athttp://www.radiomods.co.nz/forum/viewto ... f=1&t=2914 for more info on this subject.

Good luck with your problem.
Sue

[1iwilly]

sorry about that.
i was trying to explain all the stuff that was already done to the radio.
so i don't get hit with change this change that.
i'm using a bird meter. i also have the sams photofacts.

[1iwilly]

i forgot to add,i also have a multimeter,and a 6 amp power supply.

[The Defpom]

Check the voltage drop across R111 (tell us the voltage on both sides of it, in TX and RX), I have come across issues on this and similar chassis where a capacitor is loading down the DC supply causing a large voltage drop across that resistor, it sounds similar.

[1iwilly]

Check the voltage drop across R111 (tell us the voltage on both sides of it, in TX and RX), I have come across issues on this and similar chassis where a capacitor is loading down the DC supply causing a large voltage drop across that resistor, it sounds similar.

OK on one end of the resistor, i have 7.94 volts, the other end reads 8.34 volts this is on RX. on TX they don't change.???

[The Defpom]

That sounds fine at that point.

[1iwilly]

thanks to all that replied.
i think i found the problem when i was doing the 1k resistor mod. i was doing it to the middle leg of TR26.
after re checking it suppose to be TR24, now i have full swing in am.