| Author |
Message |
    
Swamper105
New member
Username: Swamper105
Post Number: 2
Registered: 12-2004
| | Posted on Monday, March 21, 2005 - 3:10 pm: | 
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receives fine on am and ssb . Transmits fine on am . The ssb side receives but I lost my transmit . So in the nut shell it works good on Am . , when I switch to SSB it will receive ok but no transmit |
2600
Advanced Member
Username: 2600
Post Number: 509
Registered: 7-2002
| | Posted on Tuesday, March 22, 2005 - 12:59 am: |
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Hate to be the one to suggest this, but that sounds like the mode (LSB/AM/USB) switch.
If you have good modulation on AM, that's the place to look.
If you just keyed the AM and saw a carrier, try to modulate it. If you have good modulation audio on AM transmit, that really does point to the mode switch.
If the AM transmit audio is dead, that's a WHOLE different story.
73
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Swamper105
New member
Username: Swamper105
Post Number: 4
Registered: 12-2004
| | Posted on Tuesday, March 22, 2005 - 7:22 pm: |
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Well it does have good modulation on Am . The only thing i can`t grasp is it switches to SSb and recives great ..if it was the switch why wouldn`t it work on at least one why is it out on both upper and lower but not AM . I cant find nothing bad on the boad unless it a small cap some where i am over looking ..I had a washington the did this and i found a small lue coil had opened . Well thanks i look into the switch if anyone elese ran into this i would appricate your input |
Kid_vicious
Intermediate Member
Username: Kid_vicious
Post Number: 300
Registered: 9-2004
| | Posted on Tuesday, March 22, 2005 - 10:33 pm: |
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i doubt its the switch, they either work or they dont. if its scratchy in the speaker when you switch from mode to mode, then spray some contact cleaner in it and switch it back and forth quickly.
matt |
Swamper105
New member
Username: Swamper105
Post Number: 6
Registered: 12-2004
| | Posted on Wednesday, March 23, 2005 - 9:27 am: |
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Ya I doudt it to but at this point i won`t over look it . Do me a favor and look threw your log book and see if you ever ran into this before or if anyone you know did . This happened to a 148 that i had here but there was no modulation on AM i found c18 to be bad . If you dont mine ask around |
Swamper105
New member
Username: Swamper105
Post Number: 8
Registered: 12-2004
| | Posted on Wednesday, March 23, 2005 - 8:10 pm: |
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Well its back the radio is working but low watts and audio out final and driver and predriver test good . This a hard one any idea? |
Kid_vicious
Intermediate Member
Username: Kid_vicious
Post Number: 308
Registered: 9-2004
| | Posted on Wednesday, March 23, 2005 - 9:20 pm: |
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swamper105, glad to hear you found the problem. now that youre encountering a new one, we need new info to help you. tell me what you know about the history of this radio. whats been done to it in the past? do you have the equip. to do an alignment on it? give me as many details as you can and as many specific numbers as possible.
what did the audio problem turn out to be?
matt |
2600
Advanced Member
Username: 2600
Post Number: 515
Registered: 7-2002
| | Posted on Thursday, March 24, 2005 - 2:26 am: |
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Uh, okay. Low wattage on AM and SSB both? Or just on SSB?
There is one pole of the mode switch that feeds 13.5 Volts straight to the final/driver for SSB, and feeds into the AM modulator at the center click of the switch. If that section of the switch goes bad, no other functions are affected.
If you don't have a 'scope available, this could be tricky to track down.
Have you checked to see if you can obtain normal bias current on the final and driver? If the driver will turn up to a normal 40 mA or so, but the final won't that's one kind of clue. But only if the collectors have a full 13.5 Volts or so on them in one SSB mode. Doesn't matter which, upper or lower.
Likewise, if you can check the DC voltage at the two pins on the main board where the bias-test hookup is WHILE IT'S KEYED AND MODULATING, that could narrow things down. Looking at it with a 'scope is better. If the voltage coming out of the mode switch is being affected, you'll see the trace jump around when you wiggle the mode switch a little. Tougher to catch with just a meter.
73
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Swamper105
New member
Username: Swamper105
Post Number: 9
Registered: 12-2004
| | Posted on Friday, March 25, 2005 - 7:17 pm: |
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Ok First I want to thank everyone . Here goes replaced all 10 volt cap`s found C18 leaking this restored madulation and Carrier .. Second problem was the 8 pin voltage reg.. Changed it a bang it came to life .. |
2600
Advanced Member
Username: 2600
Post Number: 522
Registered: 7-2002
| | Posted on Monday, March 28, 2005 - 12:15 am: |
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Congratulations, Swamper.
The 2000 is a good all-around radio. Wouldn't have stayed on the market for 15 years otherwise.
Some parts just aren't meant to last over 20 years.
73
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1861
Intermediate Member
Username: 1861
Post Number: 159
Registered: 2-2004
| | Posted on Thursday, April 28, 2005 - 8:26 pm: |
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Any techs here work on radios ? I HAVE A COBRA 2000 I NEED FIXED . Receive only works if someone is talking within a few yards . Would like to send it to someone who knows their stuff . |
Tech808
Moderator
Username: Tech808
Post Number: 5644
Registered: 8-2002
| | Posted on Thursday, April 28, 2005 - 9:19 pm: |
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1861,
Contact Copper Tech8541 / Richard at:
Tech8541@copperelectronics.com
Tech8541 is located in NC.
Hope this helps,
Lon
Tech808
CEF808
N9OSN |
1861
Intermediate Member
Username: 1861
Post Number: 160
Registered: 2-2004
| | Posted on Thursday, April 28, 2005 - 9:27 pm: |
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Thanks LON |
