cobra 29 classic erf strange??? mod done

[1iwilly]

OK today i saw a 29 ltd classic that had the 2030 mod done what caught my attention was
they put a 100 ohm resistor from pin 1 to 10 of the audio chip.?? i look at the schematic pin 1 shows 13.8 volts
I've seen a 4.7 ohm 1/2 watt
that goes from c116 + side to the gate pin of the 2030 final to gain more output Watts.

 

[Robb]

I can understand changing out the stock final for ERF-2030 if the stock final has popped. I know that a 100 ohm resistor and cap put near the final stage is used for the swing mod for this radio. But I haven't seen a mod that requires a 100 ohm resistor on the audio amp. Was the modulation limiter/diode also clipped as well?

 

[1iwilly]

I can understand changing out the stock final for ERF-2030 if the stock final has popped. I know that a 100 ohm resistor and cap put near the final stage is used for the swing mod for this radio. But I haven't seen a mod that requires a 100 ohm resistor on the audio amp. Was the modulation limiter/diode also clipped as well?

yes d11 was cut

 

[Robb]

As a pure guess; it sounds like someone used the resistor to tame the audio input because that diode was clipped. Does it sound OK from a trusted friend/radio contact?

 

[1iwilly]

As a pure guess; it sounds like someone used the resistor to tame the audio input because that diode was clipped. Does it sound OK from a trusted friend/radio contact?

from what i was told they say he sounded clean but muffle both with stock mike and d104 mike.??

 

[1iwilly]

update new info

ok today i was able to talk to the tech that did the mod from tampa fl.
he said the 100 ohm resistor is to add more voltage to the audio chip.
but here is my thing won't that make the audio chip get hotter quicker
and then messing your audio all out of proportion.???

 

[Robb]

ok today i was able to talk to the tech that did the mod from tampa fl.
he said the 100 ohm resistor is to add more voltage to the audio chip.
but here is my thing won't that make the audio chip get hotter quicker
and then messing your audio all out of proportion.???

All components have limitations as to how much current can be applied. You are right, the audio chip is no different. If he has been doing this mod long enough, he must have seen comebacks and repairs. If it is a solid mod; then he has not seen comeback/repairs. One would think that clipping the diode would have been enough. At that point, the audio should be more than enough - IMO.

Here is a popular link with many interesting Cobra 29 mods:

http://www.worldwidedx.com/radio-ra...bra-29-high-power-mod-2sc1969-transistor.html