Cobra 148 GTL-DX Channel Selectors....

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Snake Plissken
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Cobra 148 GTL-DX Channel Selectors....

Post by Snake Plissken »

Hi All.....

Can anyone confirm whether or not the channel selector in a Mk1 148 GTL-DX is the same part as used in the Mk2s?

I have a Mk2 here with a smashed selector...just a robbed-out scrapper chassis that I thought I would try to bring back, for the challenge :lol:
I don't have a replacement Mk2 selector, but I have one from (probably) a Mk1 kicking around, still on it's PCB...(someone has written '148 early' on it).

The Mk2 part is a Pulser PSS-23 (SR-209 stamped above Pulser, and 7007 below PSS-23). PCB is a PC-880 AB.

The Mk1 part is a Pulser PSS-23 (also SR-209 stamped above Pulser, but with 6911 below PSS-23). PCB on this is a PC-880 AA.

The selectors look identical, other than the 4-figure number (I'm guessing this could be the date of manufacture code?)...

The selector PCBs also look identical, other than the differing AA/AB prefix....

Just a little worried that the internals are different as I'm aware of the different PLLs used in each radio...

Cheers guys!
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Re: Cobra 148 GTL-DX Channel Selectors....

Post by cb4ever104 »

To be honest , I thought that having different PLLs , that they would be different . Saying that , it wouldn't take much to use the same one in the mk2 . Just have to map it to the binary adders . I'm not home at the moment , so I can't look . But if they're both marked SR-209 , then I'm 100% sure they'll both be the same . Nick (Black Spirit) will know for sure . BTW They're pretty easy to fix . In fact I quite enjoy stripping them down . I've only had one that I couldn't do , and that was one of the crappy flex cable ones .

Sammy
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Re: Cobra 148 GTL-DX Channel Selectors....

Post by Snake Plissken »

Hey Sammy....

Yeah...I was figuring on the same thing....
I have all the info buried somewhere on the N-codes for both radios, that's the sure-fire way of confirming it...

I'm still fairly busy removing years of 'improvements', but at least the main board is back in one piece (the frame was a diamond shape and had damaged two corners of the PCB...).

I said it was rough lol :lol:
Unidens (one or two)..
Cybernets (a few more)..
Stalker ST-9F DX Colonel FR360 Stag 357 Midland 79-900 Zodiac Tokyo Pegasus III Transceiver MkV
Cheiza CB702 workshop monitor :lol:
A few more, I forget...

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Re: Cobra 148 GTL-DX Channel Selectors....

Post by Snake Plissken »

cb4ever104 wrote: BTW They're pretty easy to fix . In fact I quite enjoy stripping them down . I've only had one that I couldn't do , and that was one of the crappy flex cable ones .

Sammy
I get the same kicks but out of bringing back damaged dual-gang controls :lol: :lol: :lol:
Unidens (one or two)..
Cybernets (a few more)..
Stalker ST-9F DX Colonel FR360 Stag 357 Midland 79-900 Zodiac Tokyo Pegasus III Transceiver MkV
Cheiza CB702 workshop monitor :lol:
A few more, I forget...

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Re: Cobra 148 GTL-DX Channel Selectors....

Post by zephyr »

The switches are both the same for the MK1 and MK2 and the N codes are the same 15 to 59.
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Re: Cobra 148 GTL-DX Channel Selectors....

Post by Snake Plissken »

As we suspected then.....

Thanks Zephyr, for confirming this! :thumbup:

I went ahead last night, and swapped over the selectors on the PCBs (the good one had a burn-out on a track on its PCB, and was missing the TX/RX LED)...

Just got to fit a driver and a final, and do a 'back to stock' on the band switch wiring....this old trooper may live again yet :lol:
Unidens (one or two)..
Cybernets (a few more)..
Stalker ST-9F DX Colonel FR360 Stag 357 Midland 79-900 Zodiac Tokyo Pegasus III Transceiver MkV
Cheiza CB702 workshop monitor :lol:
A few more, I forget...

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Re: Cobra 148 GTL-DX Channel Selectors....

Post by The Collector »

There's a Uniden-based selector, display and board on ebay at the mo. Not sure if it's for a 148 though.
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Re: Cobra 148 GTL-DX Channel Selectors....

Post by Mudslinger »

Any other radios share the same selector?

I have scrap a President Valery and Audioline homebase if anyone needs selectors from either of those.
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Re: Cobra 148 GTL-DX Channel Selectors....

Post by Queball »

If anyone is interested in channel selectors for the Cobra 148 GTLDX i have some for sale. They are hard to get hold as a spares part.
gholdq on youtube.com
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Re: Cobra 148 GTL-DX Channel Selectors....

Post by cb4ever104 »

Mudslinger wrote:Any other radios share the same selector?
I was thinking the same . Nick would know , as he works on lots of different radio . I'm assuming the Stalker 9 does . Also , possibly the rest of the old skool MB8719 radios maybe ?

Sammy
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Ex GM0 , now EA5 .
Handle "Fortune Hunter" back in "the day"
Radios ....? Anything that says "TAIWAN R.O.C" on the back.
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Re: Cobra 148 GTL-DX Channel Selectors....

Post by Snake Plissken »

The MK1 selector is indeed the same part - it's now in the radio and works perfectly....

Confirms the important bit is the N-codes being the same, as mentioned by Zephyr....so my guess is it would work in any radio with the same N codes, running either the 145106 or 8719 PLLs (maybe others too)...

This old chassis is getting closer to working now!

Fixed a problem causing it to 'transceive' in TX lol....this was a collector-emitter short on TR36, replaced this....

There is no output stage fitted yet, but I'm guessing TX will work once fitted as the TX/RX switching is now good...
Also receiving a proximity radio fine in all modes, all 3 bands....(there might be a problem with TR17 though, verry deaf until you apply the finger antenna :lolno: ).

Just a problem with audio to work out now....there is none :lol:

Just a faint 'pop' from the speaker when you switch on radio....

I think the audio amp was dead...I've tried 2 other (probably OK) TA7222APs; similar 'pop' on switch-on but also you can hear a faint 'motorboating' noise....similar to a VCO that is just out of lock...

Audio circuit is fine from audio amp. output to internal or external speaker.....I injected a signal here and it makes it to the speaker fine....same signal applied at the audio amp. input doesn't make the trip....

Is this a squelch circuit problem, maybe? I say this as the squelch amp. voltage is way off - am I right that there should be around 0.9v on pin 8 of the squelch IC, with squelch 'on' ? I'm seeing around 7 volts....

What are your thoughts on this, guys?

So far I have only replaced the 10v electrolytics for 16v ones, the rest are factory still...
Unidens (one or two)..
Cybernets (a few more)..
Stalker ST-9F DX Colonel FR360 Stag 357 Midland 79-900 Zodiac Tokyo Pegasus III Transceiver MkV
Cheiza CB702 workshop monitor :lol:
A few more, I forget...

Snake Plissken - Rescuing Presidents since a 1981 version of 1997 :D
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Re: Cobra 148 GTL-DX Channel Selectors....

Post by Snake Plissken »

Sorry - forgot to mention that when i injected audio signal at TA7222AP input, the input pin was not lifted from it's track (still connected to radio)..

So something is killing the audio before it makes it to this point? :wtf:
Unidens (one or two)..
Cybernets (a few more)..
Stalker ST-9F DX Colonel FR360 Stag 357 Midland 79-900 Zodiac Tokyo Pegasus III Transceiver MkV
Cheiza CB702 workshop monitor :lol:
A few more, I forget...

Snake Plissken - Rescuing Presidents since a 1981 version of 1997 :D
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Re: Cobra 148 GTL-DX Channel Selectors....

Post by cb4ever104 »

Sounds as if you're having fun with that "Snake" Snake :)

Haven't had that audio problem before , but I'm sure someone will have some advice on it .
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Ex GM0 , now EA5 .
Handle "Fortune Hunter" back in "the day"
Radios ....? Anything that says "TAIWAN R.O.C" on the back.
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Re: Cobra 148 GTL-DX Channel Selectors....

Post by Snake Plissken »

lol yeah Sammy, really enjoying this one....!

I think I get the most kicks out of taking the worst pile of sh!t and forcing it to work again :lol:
Unidens (one or two)..
Cybernets (a few more)..
Stalker ST-9F DX Colonel FR360 Stag 357 Midland 79-900 Zodiac Tokyo Pegasus III Transceiver MkV
Cheiza CB702 workshop monitor :lol:
A few more, I forget...

Snake Plissken - Rescuing Presidents since a 1981 version of 1997 :D
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Re: Cobra 148 GTL-DX Channel Selectors....

Post by dt307 »

Goto cb tricks and down load the service manual
Look at the block diagram you will see the audio flow from sql switch , volume vr, etc and work through it starting from the audio chip and work along the audio chain until you find the issue.
I am not home and it's hard for me to pin point
Plus I can only give general fault finding info like inject af at audio chip input,then volume vr,then sql switch etc .i have a few bad volume pots that went short. Is pa ok and am tx audio ?

Some one like nick that works on these daily may have some common problem pointers
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