148gtl mod 1990

[kaos513]

Need help identifying this mod pic below thanks its a 148gtl made in 1990 philipines.

 

[Robb]

Could you have taken that picture any farther away?
lol
How about a close-up?

 

[kaos513]

Could you have taken that picture any farther away?
lol
How about a close-up?

check now.

 

[Robb]

The one yellow wire coming from the PLL is to get extra channels.

The other cap/resistor mod is modifying the mic audio circuit.

 

[kaos513]

topside therenmore wires going into front switches

 

[ExitThirteen]

Looks like the cap/resistor mod is for the clarifier. Does the orange wire go to the clarifier pot?


~Cheers~

 

[kaos513]

Looks like the cap/resistor mod is for the clarifier. Does the orange wire go to the clarifier pot?


~Cheers~

yes goes to the clariifier

 

[ExitThirteen]

Ok, thought so. Other wires on the PLL looks like a 10khz jump mod of some sort.


~Cheers~

 

[Robb]

How does a cap/resistor used for the clarifier, if you don't mind the question.

I know that when extending range in a clarifier is done, the use of a 5.6uH choke between ground and the anode of the varactor diode is the typical mod.

Confused . . .

 

[ExitThirteen]

The resistor on the clarifier B+ wire decreases slide (or can drop +13.8V down to +8V), the capacitor helps stabilize that voltage out of the resistor. Very weird mod, almost looks like they tapped directly to the +13.8V.... can't tell 100% for sure, tho. Would need a better closeup pic of the cap/resistor and where they are soldered to.

Obviously, the easiest way to get +8V is to either tap off of pin 3 on the MB3756 voltage regulator IC, or go to the + side of C84, which is the +8V feed for the PLL control voltage.


~Cheers~

 

[melaza]

The resistor on the clarifier B+ wire decreases slide (or can drop +13.8V down to +8V), the capacitor helps stabilize that voltage out of the resistor. Very weird mod, almost looks like they tapped directly to the +13.8V.... can't tell 100% for sure, tho. Would need a better closeup pic of the cap/resistor and where they are soldered to.

Obviously, the easiest way to get +8V is to either tap off of pin 3 on the MB3756 voltage regulator IC, or go to the + side of C84, which is the +8V feed for the PLL control voltage.


~Cheers~

Hi,
Pin 1 on the MB3756, pin 3 is incorrect.

 

[ExitThirteen]

Pin 1 can be used also. It has +8V as well.

I prefer to tie to the + side of C84.


~Cheers~

 

[kaos513]

Ok, thought so. Other wires on the PLL looks like a 10khz jump mod of some sort.


~Cheers~

Pin 1 can be used also. It has +8V as well.

I prefer to tie to the + side of C84.


~Cheers~

Pin 1 can be used also. It has +8V as well.

I prefer to tie to the + side of C84.


~Cheers~

I took a chance and purchased this radio for 40 bucks and sure enough it has no issues,i will leave the mods alone and enjoy my 40 bucks.

Pin 1 can be used also. It has +8V as well.

I prefer to tie to the + side of C84.


~Cheers~

will post more pics today

 

[kaos513]

Pin 1 can be used also. It has +8V as well.

I prefer to tie to the + side of C84.


~Cheers~

 

[222DBFL]

Upper and lower freqs and a band switches i suppose? What is the frequency range?? Just curious. They are nice radios and actually even nicer when they haven't been touched at all!! But for the money you spent as long as the radio works properly you did fine for $40. Have fun with it!!