I have a uniden pro510xl hooked up to a palomar 250 as a base. When i key it up the linear squeals, (high pitched whine) the swr with amp off is around1:4 with it on is almost 1:9 to 2:1. I also have a galaxy dx949 tuned, aligned... When turned all the way down puts just a little more power out than the uniden pro510xl. The galaxy makes no squeal in the amp at all. Is the squeal good or bad? Whats with the swr difference? Im running a half wave dipole on the roof, its tuned best i can get it.
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What makes a linear squeal?
- Thread starter cjruger
- Start date
I also had this problem with a galaxy 44 and a Texas star 400 in my truck. Yet my 2950 that I currently run would not do the squeal thing. My problem was the radio I'm thinking because I tried a total of 5 radios with the same dead key other than the galaxy and none of them did it. I think the 44 was somehow letting rf get into the wrong place.
Try a ferrite choke on the power supply leads as you may have RF feeding back into the Uniden's power leads. Your radio to amp coax jumper may have RF getting back to the transceiver and the Uniden cannot cope with the RF.... try a longer coax jumper with part of it coiled up into a choke.
mechanic
mechanic
Recently had the same thing done to my 520XL and it's doing what you are describing with either my RM203P or my Texas Star DX500. (Tested it with both...separately, not running both inline). My SWR's were good, too. I think it's stray RF, and I am going to try the ferrites. Maybe I shouldn't have had the limiter clipped, but it wouldn't swing much power otherwise.
Is Radio Shack still selling the ferrites? Otherwise I may order from RF Parts.
73,
RT307
Is Radio Shack still selling the ferrites? Otherwise I may order from RF Parts.
73,
RT307
Thats the problem,the limiter was clipped...i have a friend that cant run a pwr mic in his car with the amp on...any radio with out the amp on no squeal,and any radio with pwr mic it squeals...same with the limiter clipped...73 de JW
Sounds like you need a radio with mic gain control. I normally run old Grant XL's and 148's. Usually set the mic gain about 9 or 10 o clock position. By the time I go to 12 O clock, it will start to squeel. It is because the limiter has been removed or AMC cranked all the way up. Don't need a power mic, I usually run a Road King noise cancelling mic and I have plenty of audio. Just my 2 cents. ( Usually by 12 O'clock, with radio on scope, there is a lot of clipping / flat toppong going on)
I bought a new in the box pro 510XL and turned up the modulation.clipped nothing..... Tried several mics in the mobil. D104 silver Eagle, stock mic, older but never used uniden stock mic, DM 452, and Road king RK-56 the olny mic that worked properly was the stock Mic, everything else squealed or was low,low audio....Stock mike worked with clean and clear audio. Was thinking about clipping the mod limiter. I think I found it....Is it on the opposit side of the board from the speaker ?????????
It will be rf getting into the rig. Some radios are better shielded than others hence the difference ( I've seen some cbs that don't have a shielded mic cord at all). More power the greater the problem, amplified mics make it worse. Ferrites on the mic cord and pwr leads should help. Also fit a good earth stap. 1/2 wave dipole without a balanced to unbalanced balun can cause the rf to flow back down the coax and into equipment.Simple test, watch your swr and touch your gear and give the coax a bit of a swing if swr changes at all. you have issues.Try coiling up your coax 6 to 10 turns at the ant and tape it down, coax should run 90 degrees (ie straight down on a horizontal dipole)away from ant .Hope this helps.Mark
When I had this issue, it was a bad ground...I found grounding the radio chassis and amp body helped. I also found that a loose coax connector (as in the the portion in the radio) will cause squeal too.