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CB stuff just not acting right

Discussion in 'General CB Services Discussion' started by JeepRider, Nov 15, 2015.

  1. JeepRider

    JeepRider
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    Hey everyone! I have a Uniden 980SSB. I love the radio, except one thing. For some reason, i have poor power output. I used to get 4.5 watts AM and up to 13 watts SSB. Now i get only 2.5 watts AM MAXIMUM, but SSB is unchanged. What could be the issue? I have tried and turned the AM power pot all the way up, just to see if it would help, and i only got about 2.6 watts on the watt meter if i'm lucky out of it. What could be the problem? I have a Wilson 1000 antenna with a 1.1 SWR on channel 40 and 1.6 on channel 1. Any tips will be greatly appreciated. Also, on my amp, it has preamp, but it is not working as good as it used to. Any ideas? Thanks!


     

  2. midnight special

    midnight special
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    check jumpers
     
  3. RatsoW8

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  4. JeepRider

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    My jumpers are basically new, and are in mint condition. I have checked those.
     
  5. JeepRider

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  6. 222DBFL

    222DBFL
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    Recheck coax jumpers from both radio to swr/watt meter and from meter to amp. Replace them if possible just to rule this issue out. And yes the finals will take a shizz if you rag chew a lot!! That is why Ratso posted the link. I tuned my power back on SSB to about 8 watts pep or so and on am I have it set at 2 watts swinging to about 6-8 watts pep. Radio stays nice and cool now. It will get warm with a long ragchew but not hot. Also it's not that big s deal but you may want to cut your whip a bit as its too long for the upper part of the band. Cut in 1/8" increments and I bet you can get it to tune about the same as channel 1. Go between 1, 29, and 40 and cut until you have reached the lowest readings at all the points and leave it. It's not necessary, but that high a VSWR could be why the final went out too. The Mosfets don't like high vswr from my own experience with them. Keeping the vswr to 1.3:1 or below is a good rule of thumb IMO for these cheaper Mosfets they are using. That is what the issue is. If they were to spend more on those parts though, the radio wouldn't be as cheap either most likely. I would like to see one with a good beefed up Mosfet final and a good driver as well as adding a heat sink or fab to the back of the case. Even keeping the stock power would be fine then. But the ones in the radio are rated for like 10-12 watts max. I believe. And when you get to talking for more than a couple minutes or less the back of that radio will get pretty hot. I have had my 980 for quite a while and it stays cool now with the power turned back. I don't use a power mic either. I use the Uniden Bluetooth mic. Before you give up cut the whip down some or use the lower channels for testing as they will show more of a true reading than the channel 40 readings will be due to the rise in VSWR and reflected power it will trick your meter into showing a few more watts. Am I wrong or does it show more power at channel 40 or 1?? Just curious. You may have damaged the final, but it sounds as if there are other issues if you are still getting power. At what channel did you check the power on previously to the decrease in power? Need as much info as you can provide. It's JMO. Also are you checking these readings without the amp inline as the amp may be the issue and not the radio. I have an amp that does this. Kills the power out of radio just adding it in line. Your VSWR needs to be checked with out amp in line. This will determine the true VSWR to the radio. The amp may skew these readings due to mismatch or issues with the amp. You definitely want your VSWR to be as low as possible across all 40 channels. They send the whips out normally a bit long and they need to be cut about 1/4"-1/2". I use 1/8" cuts as you can't really mess up doing it this way. And make sure you are taking readings in an open area with no obstructions within 50-100ft all around. Close all door and keep people as far away from vehicle as well. Make sure mic gain is all the way down before calibrating. I am sure you know the drill, but just in case. And for sure make sure the amp is out of line when you check the vswr. Good luck and hope you get it resolved.
     
    Steve_Buckeye likes this.
  7. RatsoW8

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    Yes. I found a lot of other 980 owners who had the same thing happen. Just Gooogle it. I never meeesed with the output either so going in and cranking things up will probably end the finals pretty quick. The mosfet finals cost about $6 each.
     
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  8. JeepRider

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    I checked the power out put without amp inline and on channels 1 and 40. I went in and turned up the power after it messed up to see if it would make a difference. i'm going to try different length coax, because i hear that could mess with it too. If all else fails, i'll grab another final. If possible, since i'm busy with school on the weekdays, i'll see if i can get a video and i'll put the link on here. After schoolntomorrow, i'll get every little detail i can, might take some time, but i'll get it done. A lot going on here at home, really busy, but i'll definitely get you guys the information you need. I really appreciate the help. This is why i love forums! :)
     
  9. 222DBFL

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    Coax length should not determine power output and if it does you have other issues. You need to cut your whip ringer the vswr readings to a more balanced reading across the entire band. As it sits your antenna is too long and changing jumpers or coax will only mask your issue if you have one. Get the antenna vswr down on the upper portion of the band. It really should be below 1.3:1 at very min. To use an amp. You may have damaged the radio due to the high vswr. At 1.6:1 it shouldn't but these Mosfets aren't very rugged and are known to fail. Heat is thier enemy and with a 1.6:1 vswr I can bet that your radio gets hotter on channel 40 compared to channel 1. Give it a try and see. And like I said the power readings will be incorrect with the vswr that high. Maybe I am wrong but it's just what I've experienced. And as far as the coax lenght. It should not matter how long it is. The 18ft crap is that, a load of crap!! Use what reaches from point a to b. If you have to change coax length to achieve a better vswr reading you most likely have other issues, like a mismatch in impedance between the amp and antenna or the radio and antenna. VSWR alone isnt the only factor to tuning an antenna. Yes it may look good on an swr meter, but place it on an antenna analyzer and see what it reads!! To each his own, but IMO, I would get that whip cut down and at least get the upper portion of the band down some on the current vswr reading of 1.6:1 on channel 40 vs. the 1.1:1 on channel 1. Again this is JMHO. Some may disagree, but with these radios they get hot and any added stress like a high vswr will create more heat in turn possibly damaging the radio and/or the amp. Again. JMO. Good day.
     
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  10. JeepRider

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    Is there a way to test a final to see if it is bad with a meter? Because if the final went junk, i'll just grab another one. I remember now, I went around a month with a 2.3 swr....forgot about that. But I would like to see about a method of testing the final somehow. I'm going to try and fiddle with it tomorrow and get back on here with some details.
     
  11. ExitThirteen

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    If the Mosfet in that radio goes bad, you will know. It doesn't go "low gain" like a bipolar transistor does. It'll go short or open, and you will not have any output. On my 980, it went short and smoked the whole RF output section in the back of the radio, and the radio now sits in the junk pile.

    The finals that Uniden uses in the 980's are absolute junk, far worse than the IRF520's that are commonly used. I have no idea what Uniden was thinking when they decided to use the RD16HHF1 finals.

    Anyhow, I'd check all your grounding points to make sure everything is secure and well grounded. Sounds like you have a ground fault somewhere. Good luck.


    ~Cheers~
     
  12. JeepRider

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    Alright guys. I got it fixed. My coax on the wilson, like i said before, was short. Around i guess 8 feet. So i took coax off another antenna. This was 15 feet 5 inches of flawless coax. I checked it over before i soldered in place. After that, i got really good SWR's, all below 1.7 without tuning, but i am still going to tune antenna. I'm thinking about grabbing an inline watt meter too. Anyway, i get around 5 watts now. But my amp, i was talking to my dad and turned the kicker on, and he said i was louder, but my signal didn't go up at all. Any ideas? Thank you ,guys for the help. I greatly appreciate it!
     
  13. 9C1Driver

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    If your running an amplifier you can't just crank up the AM carrier like you did, most small amplifiers only need 1-3 watts input dead key. What amplifier is it?
     
  14. JeepRider

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    It is a RM Italy KL200P. Is it possible i am overdriving it and causing it to not act right? My watt meter is a swr and watt combo. Has the little antenna on top of it. I was told these were not true watt meters, but more like a rough idea.
     
    #14 JeepRider, Nov 17, 2015
    Last edited: Nov 17, 2015
  15. 222DBFL

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    You can use the watt meter you have, but you need a 50 ohm dummy load to set the AM carrier (dead key), properly. And a 1.7:1 vswr is not an ideal reading to use that radio and/or amp. You are going to end up letting the smoke out soon if you keep it up. JMO. Stop where you are and before you proceed with anything else, tune the vswr down to at least 1.3:1 or less. Again, the radio and amp you are using both use MOSFET transistors that aren't very rugged and are cheap like others have said, and they will not tolerate bad VSWR for long. Yes it will work, for how long with the current vswr reading IDK. Take the amp out of line and usr the meter you have to tune the antenna like Posted above.
    If the antenna reads higher on channel 40 than on 1, the antenna is too long, same the other way, if reading is higher on 1 than 40, antenna too short.
    Then you need to get a 50 ohm dummy load and a known good watt meter. Not saying yours is bad, it's most likely just fine for what you need it to do. But you will have to have the dummy load in order to drop the AM dead key. The antenna won't work for this as its not even tuned at this point so it doesn't present a near perfect match to the radio. If you don't know much about radios and such you may want to send it to a good tech like DTB radio or someone like that to have the needed work done on the radio to use with the amp you have. Or like I said, get a dummy load and a couple of short coax jumpers. Use the dummy load to lower the am dead key to anywhere from .5-2 watts. Depending on the amp. For your radio, if you go below 2 watts the internal meters will not calibrate correctly for swr reading. So with that known, it's best to run an external swr/watt meter and set the dead key up properly for the amp being used. Forget the internal meter. Keep the amp happy. It may take a 2 watt dead key and still work properly, but most of the time with the small rm Italy amps, they like a low dead key of anywhere from .25 - 2 watts and a pep of 4-5 watts. They don't take much to over drive one. The 980 although anemic, is a good radio for these small amps if all is setup correctly. JMHO. And you can keep the final from blowing by lowering the power. At least that has worked for me. Radio is over 3yrs old and holding strong!! Or add a good heat sink or small fan to back of radio, or even have a better driver and final put in. But for now I would get the antenna tuned ASAP and don't use the amp until you have had the am dead key lowered or you're going to damage the amp. JMHO. Good day.
     

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