Cobra 142 GTL Mic wiring?

[Simbalage22]

I dont have a mic for my new rig.. I had started posting about this in antenna section, but I asked mod to close that thread because this is where this belongs.. What would be a good mic if I was in the market to purchase one? second what are the pinouts? and lastly could I buy an adapter to use one of these 4 pin Uniden mikes, or buy an end to put on this linearjet 5 wire. or midland 5 pin thats different (Doesnt fit) I have soldering skills ect.. and really like to just get something I have working to even see if this works before I buy one of the HQ mic's

 

[loosecannon]

you have a few options.

first off, i strongly agree that you should buy a relatively cheap stock mic for your radio to gauge how its working before you purchase a more expensive mic. (this chassis does not need a power mic if tuned up correctly, and usually the power mic will have squeal issues if combined with internal mods to the audio section of the radio)

you might find that a regular old hand mic is just the ticket.

here is a link to an adapter that will adapt a 4 pin cobra/uniden style mic plug (has four holes in a square and a threaded connector)
to a 5 pin cobra/uniden style plug like your radio has.

C4P5C Microphone Adapter 4 Pin to 5 Pin - Electronics Superstore www.WalcottCB.com

i would say that if you already have a 4 pin mic handy, that is your best option. you will have a mic that works with two different styles of radios.


if you dont have a mic at all, you can buy one of these:
Aries A-506 Microphone Replacement - CB Radios Plus

and one of these connectors:
CB Microphone -5 Pin Mic connector - CB Radios Plus

solder up the connector (there are numerous places online to get the mic wiring info. cbtricks.com is one of them)

dont forget about yard sales.
i always seem to be finding old stock mics in junk boxes at yard sales even when there are no cb's around.

good luck, you've got a great radio there. be sure to treat it like the classic that it is.
LC

 

[loosecannon]

almost forgot, if you just want to be able to listen to the radio before you get a mic working for it, you just need to jump two pins together on your radio's mic connector. (the receive pin to ground)

looking at your radio, and starting at the lower left side of the mic connector, the first pin is 5, then going clockwise, 4 -3 -2 -1, with 1 being the lower right pin.

pin 3 (the top middle pin) is the receive pin.
pin 2 (just to the right of pin 3) is the audio shield/ground pin.

just use an alligator clip, or whatever you have handy to jump these two pins together and you should have receive audio.

dont worry about blowing up your radio, all you will do if you get the wrong pins is possibly key the radio up, or produce a squeal from the speaker.

now you can at least listen to the radio until you are on the air.

oh, and if you wanted to key the radio up to do a quick SWR check or something, ground pin 5 to pin 2.

Later,
LC

 

[Simbalage22]

good luck, you've got a great radio there. be sure to treat it like the classic that it is.
LC

Thanks for the info.. I will definatly try that out.. Just been working with some people in the antenna section to lower the swr on my Maco V5/8 so I dont mess that radio up I have mic's all the standard from mobile uniden and some realistic ect ect.. So if I can find the wiring for these then I possibly could get an end for the one without and end, or like you said a adapter so I can use that mic for either.. Either way I will keep you posted on how this rig works when all is done

 

[Simbalage22]

almost forgot, if you just want to be able to listen to the radio before you get a mic working for it, you just need to jump two pins together on your radio's mic connector. (the receive pin to ground)

looking at your radio, and starting at the lower left side of the mic connector, the first pin is 5, then going clockwise, 4 -3 -2 -1, with 1 being the lower right pin.

pin 3 (the top middle pin) is the receive pin.
pin 2 (just to the right of pin 3) is the audio shield/ground pin.

just use an alligator clip, or whatever you have handy to jump these two pins together and you should have receive audio.

dont worry about blowing up your radio, all you will do if you get the wrong pins is possibly key the radio up, or produce a squeal from the speaker.

now you can at least listen to the radio until you are on the air.

oh, and if you wanted to key the radio up to do a quick SWR check or something, ground pin 5 to pin 2.

Later,
LC

WOW! I tried this and the radio does receive. Notice the meter lights are indeed out, and the volume is kinda scratchy when you turn the volume, but for its age they should sell some contact cleaner or something to clean that up.. Now I have to learn the upper and lower side band as I've never had this.. Which if that transmits farher I'll be wanting that feature on my mobile setup.. Thanks again for your time

 

[hotrod]

the 142 is a great base. yes ssb does work better than am .it does
take littlr more effort having to use the clarifer to tune in ssb signals
but not hard by any means.far as mics id try either a stock mic or a good
noise canselling mic like a skythumper65dx.if your radio gonna be in a room
with other people,tv,ect i reccommend a noise canselling mic. i use one daily
cause my radio equiment is in the kitchen.if ya got your own little room
id check out the astatic 878 there good sounding and not alot of money either

 

[Simbalage22]

Hey, Well as promised here is a status update...

I found out that the meters didnt work, all lights were out, and the tx rx lights didnt work.. The tx and tx light was fixed with a little kinar wire fixing the broken trace on the board.. I was wondering why there was dent in rear corner now i know someone had to have threw this old thing.. So with patience I got it back up and going... did the tx pin trick to see if it was transmitting and if that TX light worked and once I fixed the broken trace on the board all was good... Also for the meters I carefully took them out and tapped on the back of them a few times while it was on and got them to work again... Not sure if they will hold up for a lifetime, but as of current its good... The only minor annoyance (which actually bothers me the most) is the channel display is a little off (see pics)... At any rate I paid 40.00 and a 80 mile trip (both ways) for it so I cant complain.. Cant wait to get an adapter to tx.. Whats funny is that 510 that I fixed and modded stock is actually comming though my tv and such which I am now wondering whats going to happen when I run that base (even stock) that thing should be expected to push more then 10w I am assuming based on its size... But I am treating her like a old lady that has took a beaten 1 too many times...

 

[loosecannon]

well you've certainly got yourself a project radio there sir.

i imagine the seller is happy about the 80 miles distance between you. LOL

the good thing is, that radio is definitely worth fixing.
many CB's arent these days.

as for the radio being dropped, thats a bummer as it can cause all kinds of headaches.
sounds like you MIGHT have gotten lucky there.

it also sounds like you have some electronics experience since you were able to find a broken trace and repair it.

i happen to know this chassis quite well, as it was my first base station and has been my favorite chassis ever since.

it is very close to the same board as the 2000GTL.
the radio in my signature is a president madison which is the same on the inside as the 2000.
the freq counter was a custom mod.

the thing about these project radios is that you either need to find a donor radio to get certain parts from, or have the money to buy the used ones that come up for sale every so often.

you will need a new channel display.
that shouldnt be too hard to find. it is common anode.
just need to confirm that the size is the same as other ones for sale on ebay and any of them should work.

as for the meters, you can unstick them, but its not the easiest thing to do.
remove the meters from the radio.
you will see its held together with some clear tape.
carefully remove the tape and separate the meter halves so you can get at the flathead jewelers screwdriver sized slot in the base of the meter needle.
using the right sized tool, slowly turn that screw back and forth about a 1/4 turn. DO NOT turn more than 1/4 turn!
you will feel it free up and it should be good to go.

on the volume control, make sure you get real electronics contact cleaner.
NEVER NEVER use WD40 or something like that.
it will ruin the pots over time.

have fun!
LC

 

[Simbalage22]

well you've certainly got yourself a project radio there sir.

i imagine the seller is happy about the 80 miles distance between you. LOL

the good thing is, that radio is definitely worth fixing.
many CB's arent these days.

as for the radio being dropped, thats a bummer as it can cause all kinds of headaches.
sounds like you MIGHT have gotten lucky there.

it also sounds like you have some electronics experience since you were able to find a broken trace and repair it.

i happen to know this chassis quite well, as it was my first base station and has been my favorite chassis ever since.

it is very close to the same board as the 2000GTL.
the radio in my signature is a president madison which is the same on the inside as the 2000.
the freq counter was a custom mod.

the thing about these project radios is that you either need to find a donor radio to get certain parts from, or have the money to buy the used ones that come up for sale every so often.

you will need a new channel display.
that shouldnt be too hard to find. it is common anode.
just need to confirm that the size is the same as other ones for sale on ebay and any of them should work.

as for the meters, you can unstick them, but its not the easiest thing to do.
remove the meters from the radio.
you will see its held together with some clear tape.
carefully remove the tape and separate the meter halves so you can get at the flathead jewelers screwdriver sized slot in the base of the meter needle.
using the right sized tool, slowly turn that screw back and forth about a 1/4 turn. DO NOT turn more than 1/4 turn!
you will feel it free up and it should be good to go.

on the volume control, make sure you get real electronics contact cleaner.
NEVER NEVER use WD40 or something like that.
it will ruin the pots over time.

have fun!
LC

LOL... Yea because I was told it has hidden channels (which the switches he had off the side were broke so yet another repair I had to do) but yes I do have years of electrical experience as that's all I knew before the end of my career started at age 21. I sense then have fun modding game consoles and fixing things people throw out.. Like my last project a 510XL uniden (see thread) I used to be into cb's but got turned off quick when my subs and sweet 16 was taken.. So I got a smaller one (DX250 HDV) for the car and this time I have a base to learn with more, and a big dog to keep eyes on it LOL.. I am considering just replacing the knob as I just realized the knob I put on that 510XL would have worked. You wouldnt happen to know the power mods ect for this would ya? So I could see if the amc is still intact as I hate an overmodulated radio.. for them 510's its ok because their small and dont sound bad with the diode cut.. But these rigs dont sound well with AMC clipped.. Thats just my opinion

 

[loosecannon]

TR32 in the front right section of the board is the one people usually clip, even though it makes the radio sound like crap on AM and SSB.
replace it with a 2SC945 or equivalent.

also check to see if R104 has been clipped. this one only affects the AM audio, but if you want the AMC intact, this resistor needs to be there.

VR6 will set your deadkey.
VR7 will set the SSB power. (do not go over about 15 watts)

L36 and L37 near the driver and final are your TX peaking adjustments.
make sure you tune them for max "modulated" power while saying "ahhh" into the mic.
do not tune them for max deadkey or you will end up with downward modulation.
LC

 

[Simbalage22]

Thank you all

TR32 in the front right section of the board is the one people usually clip, even though it makes the radio sound like crap on AM and SSB.
replace it with a 2SC945 or equivalent.

also check to see if R104 has been clipped. this one only affects the AM audio, but if you want the AMC intact, this resistor needs to be there.

VR6 will set your deadkey.
VR7 will set the SSB power. (do not go over about 15 watts)

L36 and L37 near the driver and final are your TX peaking adjustments.
make sure you tune them for max "modulated" power while saying "ahhh" into the mic.
do not tune them for max deadkey or you will end up with downward modulation.
LC

I MUST USE CAPS THANKS YOU ALLL!!!!!!

Sorry I didnt reply sooner, I been on channel 19 making friends with the cobra 142.. I met a guy talking on my 510 uniden and he said yea I've got a 5 pin connector..2.15 and its urs.. So I got it and attached it to an old midland I had laying around.. They say the radio is loud and proud, and sounds better with the linear off (makes a 2db difference) The radio is showing a dosy reading of 2w and swinging to around 11 which I thought would be higher, but according to everyone that was on it was a good souning modulation and unit.. I will check the amc and make sure its intact.. Thanks for the info.. BlueCamaro is my handle.. hopes to see you all on the band

 

[Simbalage22]

TR32 in the front right section of the board is the one people usually clip, even though it makes the radio sound like crap on AM and SSB.
replace it with a 2SC945 or equivalent.

also check to see if R104 has been clipped. this one only affects the AM audio, but if you want the AMC intact, this resistor needs to be there.

VR6 will set your deadkey.
VR7 will set the SSB power. (do not go over about 15 watts)

L36 and L37 near the driver and final are your TX peaking adjustments.
make sure you tune them for max "modulated" power while saying "ahhh" into the mic.
do not tune them for max deadkey or you will end up with downward modulation.
LC

Hey its almost 5am and I was going to open her up to check the above, but before I do just out of curiousity what should the voltage from the power supply be at? I just ask because I think they might have upped the rail voltage to get more power out of it and thats possibly what killed all the lights ect... So I want to check that as well.. We all like our radios to have high output, but not at the expense that will fry the internals over time

 

[mrgumby]

be carefull turning up the watts on that radio..they have weak regulators....I really wouldn't turn up the watts .just turn the modulation up and leave the watts alone

 

[loosecannon]

mrgumby has a point there.

look at TR34.
its mounted to the wall in the rear right section.
if it says 1419 on it, you should replace it with an NTE152 or 2N6487 or equivalent.
they were borderline rated for 4 watts, and dont do well when the power is turned up.

as for the power supply, set it at 14 volts.

looking at the schematic for this radio, i noticed that L37 is not a variable coil, it is part of the trap section and should not be messed with.

also, dont mess with L39.
it is the TVI filter and turning it can cause all kinds of harmonics and bleedover.
LC

 

[Simbalage22]

mrgumby has a point there.

look at TR34.
its mounted to the wall in the rear right section.
if it says 1419 on it, you should replace it with an NTE152 or 2N6487 or equivalent.
they were borderline rated for 4 watts, and dont do well when the power is turned up.

as for the power supply, set it at 14 volts.

looking at the schematic for this radio, i noticed that L37 is not a variable coil, it is part of the trap section and should not be messed with.

also, dont mess with L39.
it is the TVI filter and turning it can cause all kinds of harmonics and bleedover.
LC

Is that variable pot on the power supply board for the power out? Good info. I havent messed with any of them.. Its around 2w deadkey and swings nicely to around 12. If thats normal for this radio then I guess its ok. I may look into upgrading the final as you mention. Did that once on a newer cobra with weather and made such a difference. Got my D-104 (TuG8) and wired the end for 5 pin cobra.. Thing squeels if dyna is all the way up.. Quarter way sounds good.