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Nightshift221
New member
Username: Nightshift221
Post Number: 9
Registered: 2-2005
| | Posted on Monday, February 26, 2007 - 6:01 pm: | 
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I HAVE A 148 GTL AND THE RECEIVE IS OUT RADIO TRANSMITES WELL AND I ALREADY HAVE RULED OUT THAT IT IS NOT THE MIC ANY SUGGESTIONS |
Hotwire
Senior Member
Username: Hotwire
Post Number: 2186
Registered: 1-2005
| | Posted on Tuesday, February 27, 2007 - 11:56 am: |
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Hello Nightshift,Does S/RF meter show signal present? You say transmit works well? You have good strong modulation? Have you tried an external speaker? You could simply have a bad speaker. Check all the little connections in the audio circuit for broken wires and broken solder connections. Such as the little wires and solder connections that go to the external speaker jack. Check the speaker jack, make sure it it working properly. Check all audio output devices, even your internal mic connections in the radio and inside the mic. ( Old radios- You may even investigate the the channel selector knob and look for missing crystals or crystals that have broke free from soldered connections.)
This type of problem is ussually super simple 99% of the time.
good luck
Kenny
cef491(27.115lsb)
2sf491(27.555usb)
Indiana
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Blackjack
New member
Username: Blackjack
Post Number: 1
Registered: 2-2007
| | Posted on Friday, March 02, 2007 - 2:08 am: |
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HELLO ALL, i have acquired a very rare cobra 148 gtl dx, blackface, no date of manufacture, the only thing written on the back is '' MADE IN JAPAN'',im guessing it was possibly produced in thelate 70's to mid 80's, its not your standard 148dx chrome face, this radio has an srf meter,no swr, has a band selector knob from A- F, RG GAIN CONSIST OF A 3 POSITION SWITCH..DX,MED,LOCAL, HAS A HIGH ,MED,LOW POWER SWITCH AS WELL, AM/FM/CW/USB/LSB, GREEN CHANNEL L.E.D., THE RADIO I BELEIVE HAS NOT BEEN USED MUCH,ITS LIKE NEW, THE ONE THING THAT BAFFLES ME IS THE SQUELCH KNOB DOESNT ENGAGE,IVE NEVER SEEN A DEFECTIVE SQUELCH IN ALL THE YEARS IVE BEEN INTO C.B.,CAN IT HAVE BEEN DISABLED ,OR POSSIBLY DEFECTIVE,I DONT KNOW IF THATS POPULAR IN SOME COUNTRIES TO DISABLE IT FOR DX OR SOOMETHING, IVE SPENT HOURS TRYING TO FIND INFO ON THE RADIO ALL OVER THE NET,FOUND NOTHING EXCEPT A PIC IN A RADIO MUSEUM, ANY INFO WOULD BE GREATLY APPRECIATED. |
Kid_vicious
Senior Member
Username: Kid_vicious
Post Number: 2440
Registered: 9-2004
| | Posted on Saturday, March 03, 2007 - 9:58 pm: |
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blackjack, i suspect that the squelch pot was converted to some other function. probably variable deadkey, or echo.
try keying the mic, looking at the meter, and turning the knob back and forth.
if the S-meter on the radio varies with your knob movement; you probably have variable power out.
also, you can open the radio and look at the wires going to the squelch pot. do they look factory?
best of luck.
matt
oh, nightshift, bad electrolytic caps are a notorious problem in the older 148s. not a design flaw, just old radios. they dry out causing all kinds of head scratching.
check all the 10 volt caps in the radio.
try replacing C95.
good luck,
matt |
Blackjack
New member
Username: Blackjack
Post Number: 2
Registered: 2-2007
| | Posted on Sunday, March 04, 2007 - 12:31 pm: |
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Thanx for the reply Matt,i appreciate it, i did key the radio and watch the s meter,i didnt notice any changes as far as wattage,or modulation whith the mic keyed up while turning the knob back & forth,including texsting on an external meter, WHAT I DID NOTICE IS WHEN U ROTATE THE KNOB FROM LEFT TO RIGHT, IF SOMEONE IS COMING IN WITH SAY A 7 ON THE SIGNAL,WHEN I ROTATE IT FULLY TO THE RIGHT,THEY DROP TO A 6,ABOUT A 1DB DIFFERENCE,NOTHING VERY NOTICEABLY,I WAS THINKING MAYBE ITS SET UP FOR A FINE COURSE SINCE THAT PARTICULAR RADIO ONLY HAS 1 CLARIFIER KNOB TO TUNE IN SSB,MAYBE THAT WAS ADDED AS AN ENHANCEMENT? ITS JUST A DB DIFERENCE ON THE RECIEBVE,NO VRAIANCE ON TRANSMIT,THE RADIO HAS THE FACTORY HIGH/MED/LOW POWER SWITCH,SO THATS KINDA LIKE HAVING A WATTAGE CONTROL IN ITSELF,ON LOW IT KEYS UP AT 1 WATT & SWINGS TO ABOUT 10,ILL TAKE A GOOD LOOK AT THE WIRES GOING GO THE SQUELCH POT,SEE IF THEY LOOK FACTORY & LET YA KNOW WHAT I FIND OUT,THANX AGAIN BROTHER |
Kid_vicious
Senior Member
Username: Kid_vicious
Post Number: 2446
Registered: 9-2004
| | Posted on Sunday, March 04, 2007 - 11:54 pm: |
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sorry about the confusion,the thread is titled 148gtl, and the part number i gave you is for that radio, not the DX models.
sounds like a nice radio and i am confused as well.
its possible that there is a problem in the squelch amp circuit, but you need some test equip. to trace that.
just so you know, one S-unit translates to 6db on most S meters.
this is why you need to increase your output power by 4X to get a gain of 1 S-unit in someone's receiver.
there is one more thing we can try.
it is very possible that someone went inside and turned the wron pot trying for more modulation or power, and turned the squelch adjustment inside the radio all the way one way.
look at the PC board closely and tell me what the board number is.
it might be PC-xxx, or EPT-XXX etc.
once i know the board number, i can tell you which pot to try and turn.
matt |
Blackjack
New member
Username: Blackjack
Post Number: 3
Registered: 2-2007
| | Posted on Monday, March 05, 2007 - 3:18 am: |
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what i did find out was it was modified to be a fine course,since the radio only has 1 knob,the clarifier,for sideband,i talked to a friend on sideband and noticed it helped fine tune them in, would u or anyone know if that particular model the the ''fake'' 148 dx,it resembles a supserstar 2200,,except for this radio has bands a-f,the superstar is bands a-e,otherwise all controls /switches are exactly the same |
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