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Message |
    
Css123456
New member
Username: Css123456
Post Number: 1
Registered: 9-2006
| | Posted on Wednesday, September 13, 2006 - 2:21 am: | 
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I have a galaxy saturn PCB ept360010A that has developed a weird problem, it has uneven power across the bands , if i tune it on 20 i can get 4 watts , when the channel is changed to 1 i get about 1 watt. some bands dont even show output at all. I thought it may have something to do with the vco but cant find the problem, i have checked the alignment and everything seems to be within tolerance. If you have any insight on this problem please steer me in the direction i need to go. |
Kid_vicious
Senior Member
Username: Kid_vicious
Post Number: 2069
Registered: 9-2004
| | Posted on Friday, September 15, 2006 - 12:01 am: |
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if the problem was with the VCO, then you would show absolutely no power output because the VCO would be "out of lock". if there is any power output whatsoever, then the VCO is doing its job.
sounds to me like the problem is in the transmit mixer section.
there are some coils that are to be tuned at whatever the center freq. of your spread is, and some that are to be tuned at the top and bottom band edges. you bounce back and forth between the top and bottom band edges attempting to achieve even power output across the band.
if someone gave the transmitter a tune up and only used ch.19 for example; the radio would show this exact phenomenon.
so if you recently had the radio "peaked and tuned", this may have happened.
try to find a galaxy service manual. it will give you the proper alignment procedures to get it evened out.
if i can find mine, i will post the procedure.
good luck,
matt |
Css123456
New member
Username: Css123456
Post Number: 2
Registered: 9-2006
| | Posted on Saturday, September 16, 2006 - 1:25 am: |
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I have a copy of a full service manual coming from an auction site, the one i have now doesnt seem to be complete and thorough. i will let you know what happens, i thoughts this was a weird problem because the radio is supposed to output 30 watts and i can only get 4 if i do a standard tuneup in the transmit section, so basically what i am getting from you is that those inductors may be set to tune at 30 watts on say 27.955 and i need to balance them out until i get 30w across the whole spectrum? i have checked the finals and they showed to be good but the problem was giving me a headache so i replaced them any way with some used ones out of another radio that was up to par. Man i sure hope you are right because i would like to get this radio up. everything works, audio is good, except for the low uneven power. thanks for the tip, will let you know! |
Kid_vicious
Senior Member
Username: Kid_vicious
Post Number: 2073
Registered: 9-2004
| | Posted on Saturday, September 16, 2006 - 10:56 pm: |
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no problem,
your transmit mixer section has a certain "bandwidth" that it will cover. if you've ever heard someone talking about broadbanding their radio, they might have been doing it to the transmit mixer so that their radio would have a higher power output on the extra channels that they put in their radio.
your transmit mixer has to be quite broadbanded to cover the range of freqs. that the radio will cover.
here's the thing. your radio was designed and built to be a 10 meter radio, and cover 28-29.7mhz.
thats 1.7mhz of freq. range.
the manufacturers of the radio dont want to spend any extra money they dont have to, so its a good bet that the mixer cant cover much more than this range, maybe 2mhz.
so once you do the freq. mod to get the CB band, the radio is not aligned for this freq. range, and the power out and receive sensitivity will be out of whack.
so what you have to do is pick which 2 mhz you want to tune the radio to. 25-27, 26-28, 27-29, etc... and go to the center of that range to do the alignment.
so if you chose 26-28 mhz, then you would start your alignment on 27 mhz, and when the alignment tells you to go to 29.7mhz, you would use 28.000 mhz.
does that make sense?
dont mess around with the synthesizer alignment unless something is really wrong there, and it doesnt sound like there is.
always do the VCO tuning on the channel they specify in the service manual.
read through this thread im linking you to, it is for a 148gtl, but will give you an idea of what an alignment entails, and is written in easy to understand language.
http://www.copperelectronics.com/cgi-bin/discus4/show.cgi?tpc=34&post=113535#POST113535
good luck,
matt |
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