Cobra 2000 GTL DeBunking

[88_bandit]

Okay I recently purchased a used 2000 and upon receiving i noticed a weird modificaton. It is using the CB/PA switch and is hooked up to the PLL area and consists of:
1 - c945 transistor
2 - 4148 diodes
1 - 10k Ohm resistor

Also there is a 4148 diode on the bottem side of the power supply board with a cut trace???
Any help would be much appreciated.

73's

 

[Recon]

Okay I recently purchased a used 2000 and upon receiving i noticed a weird modificaton. It is using the CB/PA switch and is hooked up to the PLL area and consists of:
1 - c945 transistor
2 - 4148 diodes
1 - 10k Ohm resistor

Also there is a 4148 diode on the bottem side of the power supply board with a cut trace???
Any help would be much appreciated.

73'sView attachment 60666

Does it transmit and receive?

 

[1iwilly]

that's a very old-school channel mod

 

[TM86]

Just a guess that it's a channel mod to give an extra "band" of 40 channels outside the legal ones.

 

[88_bandit]

 

[Recon]

that's a very old-school channel mod

What is the purpose of the mod?

 

[1iwilly]

What is the purpose of the mod?

way back in the day people enjoy going either to the lower channels or upper channels to talk they call it freebanding some people use it as private channels to carry a long conversation with out interruption and the list goes on

 

[nomadradio]

If you know what frequency each of the legal 40 channels should show, you can see what frequencies above 40 or below channel 1 you'll get by flipping the PA and ANL (maybe?) switches. They will change the counter reading on some of the 40 channels, but not all.

That radio has more secret sauce in it than a Kansas City barbecue joint.

73

 

[Rwb]

If you know what frequency each of the legal 40 channels should show, you can see what frequencies above 40 or below channel 1 you'll get by flipping the PA and ANL (maybe?) switches. They will change the counter reading on some of the 40 channels, but not all.

That radio has more secret sauce in it than a Kansas City barbecue joint.

73

old sears roadtalker i got has 5 extra bands.every band has about 15 diffrent frequincys from standard 40. and not in sequnch either

 

[NZ8N]

Pin 11 - Grounding this drops you 320kc (or 32 channels from whatever Pin 10 is set to.
If Pin 10 is high (normally open or floating) then Ch 15 becomes 26.815 MHz, or
If Pin 10 is low (grounded) then Ch 15 becomes 27.455 MHz

Pin 10 - Normally open or floating (pulled high with internal resistor), grounding this pin "bumps" you up by 640kc, or the equivalent to 64 channels, which puts Ch 1 to 27.605 MHz.

Pin 9 - +8v VCC PLL chip supply pin.

http://www.cbtricks.com/pub/secret_cb/vol_15/graphics/secret_cb_vol_15_pg25_28.pdf

Page 3 (of 4) gives you the frequency chart.

They did not implement Pin 12 or Pin 13 to backfill frequencies missed by the above mod (27.425 for instance).

 

[ShakyMcQuiver]

Search the net for 'Digimax Lite'. These are a microprocessor type of mod that gives you all the channels, even the A's and displays it correctly on your counter.

When I bought my Cobra 2000 it had the extra crystals wired up to one of the radio's switches too. Very poorly done BTW.

Before Arduinos and other microcontroller type of kits, I made my own crystal board using relays. It's much more stable, but by no means perfect. Basically it's like the old Expo kits but without the rotary switch (that stick or fail).

I want to eventually upgrade to the Digimax system, (the word 'eventually' in this case means... when the WIFE says I can) LOL!

I wish I still had my old college stuff. I've done some microcontroller work. Loads of fun!

 

[Woody-202]

Search the net for 'Digimax Lite'. These are a microprocessor type of mod that gives you all the channels, even the A's and displays it correctly on your counter.

When I bought my Cobra 2000 it had the extra crystals wired up to one of the radio's switches too. Very poorly done BTW.

Before Arduinos and other microcontroller type of kits, I made my own crystal board using relays. It's much more stable, but by no means perfect. Basically it's like the old Expo kits but without the rotary switch (that stick or fail).

I want to eventually upgrade to the Digimax system, (the word 'eventually' in this case means... when the WIFE says I can) LOL!

I wish I still had my old college stuff. I've done some microcontroller work. Loads of fun!

Yep, I like my DigiMax. Have one in a 29xlr and another in a 148gtl