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Author Topic: Atlas 210x won't transmit  (Read 2837 times)
KJ4KET
Member

Posts: 73




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« on: April 17, 2011, 09:04:17 AM »

My Atlas 210x has stopped transmitting.  Here is a simplified chronology of events:

Last week - the radio intermittently stopped transmitting while installed in my truck.  A good whack on the top solved the problem.

It worked all the next day until coming home from work.  On the way home, I made a contact with a mobile station in Kansas, and immediately afterwards, the Atlas stopped transmitting and will no longer transmit. It still receives just fine.

Of course, my immediate suspicion is blown finals, but it seems odd if you look at the chronology, that something was intermittent and solved with a sharp tap on the lid, and it worked after that. Then again, I tested the voltage out of my truck, and sometimes it runs high - close to 15v before settling down to 13.8v.

I guess I will just have to borrow an oscilloscope and put a signal tracer on it, and test a few voltages etc., but before I start to do all this, I wondered if anyone has any ideas. Can final output transistors work intermittently while failing gradually?  I would have though not, that they either work or not, but who knows.

I love this radio and definitely want to repair it.  Any suggestions will be gratefully received.

David
KJ4KET
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KE3WD
Member

Posts: 5689




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« Reply #1 on: April 17, 2011, 03:23:23 PM »

Likely a bad connection somewhere. 

Could be a connector, could be a solder joint or...

Might be easy to find on testbench when open, attempt to xmit into dummy load and poke. prod and tap around likely areas using an insulated spudger.  Also flex circuit boards a bit. 

73
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K8AXW
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Posts: 4001




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« Reply #2 on: April 17, 2011, 08:34:12 PM »

Sounds something like my old Kenwood TS-830S.  Found that Kenwood never installed star washers between the PCB and the metal frame.  Open it up and tighten down the ground screws on the PCBs.

Follow 3WD's suggestions.
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WA9AFM
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Posts: 208




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« Reply #3 on: April 18, 2011, 07:29:00 PM »

Had a 210X once and wish I had it back.   I had a similar problem and reseating the boards solved it.  As previously mentioned, give the grounding points for the boards a close look also.
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KJ4KET
Member

Posts: 73




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« Reply #4 on: April 19, 2011, 10:05:02 AM »

UPDATE:  I found that one of the wires from the little toroidal transformer that couples the power stage pre-amplifier to the driver transistor was broken.  I re-soldered it, and I can now get power out.  HOWEVER this does not fix the problem.  The resting bias current (measured by looking at the ammeter with the microphone keyed and mic level down) is almost the same as the current in CW mode.  I cannot adjust it down to the proper level as the bias adjust potentiometer will not adjust down that far. Any suggestions? 
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WD4CHP
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Posts: 147




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« Reply #5 on: April 21, 2011, 05:40:59 AM »

I have an atlas 210, 210x and a 215x.

I found a project board a RadioShack that plugged into the sockets on the main board. I also found the sockets there. I made a standoff board. It made troubleshooting a lot easier.

The 210x was an outstanding mobile rig coupled to an origional Outbacker antenna.
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