| Author |
Message |
    
Snapperhead
| | Posted on Sunday, February 02, 2003 - 11:21 pm: | 
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Hey guys, I have a galaxy Saturn that mysteriously went dead on TX. RX is just fine, only transmit isn't working....I keyed it up to check on my Dosy meters and it's showing about a 10th of a watt on em....If driver and finals were blown wouldn't it have no RX as well as no TX.....Any help would be appreciated....Thanks |
307
| | Posted on Monday, February 03, 2003 - 4:10 pm: |
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Does it still work on Sideband? If so , the AM Power Regulator is out. If it does not work most likely the final and or driver is out.
307 |
2600
| | Posted on Tuesday, February 04, 2003 - 1:02 am: |
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If it's dead on both AM and SSB, check the "mirror board". It's a small 1 inch by 2 inch or so rectangle of circuit board material, with shiny foil. It's stuck down into three fork-shaped spring contacts, just to the front from the driver and final transistors. They can come loose, or the soldering underneath them, maybe. It's the cheapest thing to go wrong I can think of.
If you have a voltmeter, put the red probe onto the mirror board, and the black one to the negative side of the big, fat filter capacitor. If you don't have at least 12 volts on SSB transmit, leave the finals and driver alone. Good ones don't give you power until you can get power onto them.
73 |
Snapperhead
| | Posted on Tuesday, February 04, 2003 - 7:10 pm: |
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2600, thanks for advice. I'll check it out....Hey 307. Didn't mean to post this on open forum....When I posted this question, I posted it at night before I turned in.....Checked it in the morning before I went to work and it wasn't posted.....I try to post stuff where they go......Thanks you guys....73's |
Snapperhead
| | Posted on Wednesday, February 05, 2003 - 8:17 am: |
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Hey 2600, I checked power source like you described and it was putting out 15.4 volts on SSB and 4 to 8 volts on AM depending on RF power knob setting....I went ahead and ordered a 2sc2166 driver and two 2sc2312's for the finals...
I notice one thing also, the tuning slug right next to the finals is really loose. the little copper wire that wraps around the bottom of slug is intact...but plastic housing and ceramic slug is really, really loose.....What effect will this have on rig.......Thanks again..... |
2600
| | Posted on Saturday, February 08, 2003 - 1:24 am: |
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If you unscrew the slug and insert a small sliver of rubber band, it will take up the slack when you insert the slug and adjust it for max modulated forward swing. The wire wants to untwist from the plastic coil form. It's just not glued to the form very well in the first place. So long as the wire ends of the winding don't pull loose from the solder it doesn't seem to make a big difference. It's not uncommon for one of them to work loose. Take a close look under the circuit board at those two connections. If it has pulled away from the solder, this could be a very cheap fix.
73 |
Snapperhead
| | Posted on Sunday, February 09, 2003 - 2:24 am: |
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Thanks 2600 on tip for Slug....Now,,,here's the deal..I replaced 2SC2166 driver and two 2SC2312's for the finals....Got great swing and modulation on AM ONLY....SSB is dead no wattage and no modulation.......Any advice on where to check or replace next.....Thanks again.... |
307
| | Posted on Sunday, February 09, 2003 - 4:50 pm: |
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I would have to guess that the local oscillator (Sideband) is not coming on when in the SSB mode...The AM carrier oscillator is turned off in SSB mode and other things happen. 2600?
307 |
2600
| | Posted on Monday, February 10, 2003 - 1:25 am: |
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I gotta ask first, does it receive on SSB okay? That one fact would trim a few branches off the "fault tree" here. Losing JUST the SSB transmit is a symptom I really don't see often.
73 |
Snapperhead
| | Posted on Monday, February 10, 2003 - 8:21 am: |
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Recieve on SSB is fine.....Just no wattage or modulation when TX........ |
2600
| | Posted on Wednesday, February 12, 2003 - 1:13 am: |
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Next step is to tune in the same channel on a nearby radio. A mobile on a power pack will do. Plug a coax jumper into the second radio and use the tip of the plug on the free end to "sniff" near the driver stage while keying the Saturn on SSB and talking into the mike. If you hear anything at all, go back and check to see that you still have DC power on the "mirror board" on SSB transmit. If the second radio is dead silent, no sound at all, the list of things to check gets longer. You might check to see that VR12, the SSB ALC trimpot hasn't been turned all the way down. That could cut your SSB wattage to zero.
73 |
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