Looking for cobra 1000 mods

[941Texas]

I have just purchased a fair cobra 1000. i would like to do the rc/npc mods along with the channel mod. or really just any useful mods you may have. i have googled my brains out trying to find any info. can anyone point me in the right direction on where a good list of 1000 mods are.

thanks 941

 

[Robb]

VR 6 for modulation adjustment - or cut D16 to disable limiter. Personally, I would just adjust VR 6 and leave the limiter intact. Especially if you are going to use a D104 power mic - or equivalent.

L17, L16, and L13 for AM power output.

And - of course - if you haven't done these mods before; then send it to a shop to get it done.

My first base station was a Cobra 1000GTL. I liked it and had a lot of fun with that radio.

 

[941Texas]

thanks for the info. do you know if there are any receive mods or swing mod for this radio?

941

 

[Robb]

thanks for the info. do you know if there are any receive mods or swing mod for this radio?

941

I never had the chance to do that mod with this radio.
I'm sure someone here might know where to replace that one receive amp transistor with a Sanyo 2SC2999E - and the noise blanketer/recieve sensitivity diodes with the four replacement 1N6263's. But I don't have the location numbers for them.

 

[MisterFatty]

Chassis is the same as the 89GTL, Late Zach T, 87GTL, and pretty much the 29GTL. Technically speaking there is no public NPC-RC mod. However you can get virtually the same effect by using the so-called SuperTalk. I have an 89GTL which will vary DK from about 50MW to about 9W, and maintain the same PEP output (35+ from what i remember). You can probably compare locations with a 29GTL for Shottky/2999 mod....

10k Pot can be subbed in place of the RF Gain, or you could use different resistances on a 3 position switch for a H/M/L type arrangement

Edit: BTW, this chassis is a real screamer setup properly...

 

[941Texas]

thanks guys, this info will get me going in the right direction. the radio should get here in the next couple days. i cant wait to play with it. i will post my results.

941

 

[loosecannon]

941,

just looked at the schematic for this radio and here are some places to start modding.

for the receiver: buy the 2SC2999/ 1N6263 receive kit off of ebay. they should be easy enough to find for under 10 bucks.

replace TR2 (2SC1674) with the 2SC2999 transistor.

replace D6, D7, and D28 with the diodes that come with the kit.

as for the "NPC" mod, i think what you mean is a "swing kit" which does reduce the carrier while maintaining the max modulated wattage that the radio has when peaked.

it is indeed R49 that you want to remove and play with the value of to set the dead key where you want it.
if you want to do the variable thing that is just fine, but if you want to set the deadkey where you want it and leave it there, just increase the value of R49 until you get what you want.
the stock value is 4.7ohms. so buy a 5.6 ohm, a 6.8 ohm, and a 10 ohm 1/2 or 1 watt resistors, and see what deadkey they give you.

the trick is to tune up the radio before you do the "swing mod".

first turn up the modulation pot, then, while saying "teeeesssst" (test) into the mic, tune the tuning coils listed above for max PEP wattage on your meter.

when that is done, then play with the value of R49 and set the deadkey where you want it for your amp.
if you are not running an amp, then there is no reason to play with the deadkey.

a swing kit does not give the radio anymore modulated power, it only reduces the carrier while maintaining what the radio already has.

as for the capacitor that is used in the swing mods, im not really sure why that is used, as once the carrier is present, the anti-spiking diode is already forward biased, and the modulation comes through 1:1.

maybe someone can explain the use of the cap to me as there is lots i dont understand about this stuff yet.

after doing these mods, and giving the radio a full alignment, it should be one bad ass radio.

good luck,
LC

 

[941Texas]

i have all this great info and still no radio to use it on. some people are really slow on shipping.

941

 

[941Texas]

well the radio finally made it. not very clean but oh well. did the rx upgrade. scoped the signal from a generator before and after. very little change. now with noise and the anl there was a very noticeable change before and after. so now on to the power mods.

as is the radio is dead keying 5 watts and forward to 5.5 with a whistle. lets see how we can improve on this.

941

 

[Switch Kit]

941,

just looked at the schematic for this radio and here are some places to start modding.

for the receiver: buy the 2SC2999/ 1N6263 receive kit off of ebay. they should be easy enough to find for under 10 bucks.

replace TR2 (2SC1674) with the 2SC2999 transistor.

replace D6, D7, and D28 with the diodes that come with the kit.

as for the "NPC" mod, i think what you mean is a "swing kit" which does reduce the carrier while maintaining the max modulated wattage that the radio has when peaked.

it is indeed R49 that you want to remove and play with the value of to set the dead key where you want it.
if you want to do the variable thing that is just fine, but if you want to set the deadkey where you want it and leave it there, just increase the value of R49 until you get what you want.
the stock value is 4.7ohms. so buy a 5.6 ohm, a 6.8 ohm, and a 10 ohm 1/2 or 1 watt resistors, and see what deadkey they give you.

the trick is to tune up the radio before you do the "swing mod".

first turn up the modulation pot, then, while saying "teeeesssst" (test) into the mic, tune the tuning coils listed above for max PEP wattage on your meter.

when that is done, then play with the value of R49 and set the deadkey where you want it for your amp.
if you are not running an amp, then there is no reason to play with the deadkey.

a swing kit does not give the radio anymore modulated power, it only reduces the carrier while maintaining what the radio already has.

as for the capacitor that is used in the swing mods, im not really sure why that is used, as once the carrier is present, the anti-spiking diode is already forward biased, and the modulation comes through 1:1.

maybe someone can explain the use of the cap to me as there is lots i dont understand about this stuff yet.

after doing these mods, and giving the radio a full alignment, it should be one bad ass radio.

good luck,
LC

The cap usage is a god question LC ? Most of these cap/resistor mods have always been done on AM radios with the jumper removed then the cap then the resistor (variable) until the DK is what your looking for. (There are many variables that can be used concerning the cap/resistors as well) I have had very little experience with the Cobra 1000s or the Uniden Zachary T's .

although as stated , the Cobra 1000s are using a resistor and not a jumper from the get go. So why no cap used on these ? or would it be by modders choice here ? Many years ago , I used Mr Fatties (I think I first saw on it Plow Boys site , (may geocities rest in peace) tip mod , they worked very good but I really didn't see much difference between a nice healthy cap and a 1 watt resistor used , and plus they were alot less work compared to the tip mod's.

Kind of reminded me of the old Retards swing kit they were always pushing with a tip. You can even put a variable trim pot in the radio that will work like a variable on the radio , IM not sure what the right name is for those ? there either a variable cap or variable resistor. (little blue guys with a little white button you can adjust)

Your question is a good one. But many of us know what techs (some) think about swing kits to begin with. Oh well. :bdh: oh , they also seem to use the cap with the tip mods.

 

[steellegs]

is it permissable to print the diagram shown above? these writtings are good theory as to best way to mod and why but iwas always a "picture " teacher like rickie -ican "splain it "better-- general question.

 

[Harley3315]

Anyone have info on how to add the expo 1000 kit to these says remove coupling cap and replace with the one from kit on cb tricks which one is that? I have a kit just not the full instructions to use it.

 

[nomadradio]

The placement of the coupling cap depends on the identity of the radio circuit board being modified.

What we do is to pull out one end of the cap and insert one lead of the new cap into the circuit-board hole that this opened up. The flying end of the old and new caps get soldered together, and the white wire goes there at the junction of the two caps. There is another cap that gets removed, usually attached to pin 4 of the 7310 chip where the drive signal from the kit is being fed to.

Exact placement and the callout numbers on the schematic will be different for the different models and circuit boards that use the Expo "A" kits.

73

 

[Harley3315]

Working with a pc407-ac here Nomadradio cobra 1000gtl was told by another fellow just attach the white wire to the front side of c79 should work??

 

[nomadradio]

Pretty sure it's the rear-most side of C79 that leads to pin 4 of IC2. Won't hurt to try just hooking the white wire there. DO NOT connect the white wire to the side of C79 connected to L19. We pull out the front lead of C79 and insert a 22pf cap in the pc board hole. The two 'flying' leads get soldered together and the white wire goes to that junction.

This makes the extra channels less affected by the setting of L19.

More than one way to skin a cat. Our interest is served by making sure it won't act up if it's operated mobile at low temperatures. More than one way of doing this will be fine at room temperatures only. And if it's a base that will never be operated mobile, who cares, anyway.

73