| Author |
Message |
    
Radiodude
| | Posted on Saturday, March 09, 2002 - 9:47 pm: | 
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I have a Palomar TX150 that has a problem It has a burnt part.The part connects to the high/low switch and I guess it is a resistor It has a gold band at one end and the middle is burnt so I cant tell what the color is and the last band is orange. I can replace the part but I need to know what the value is of this part. I hope someone can help |
Ss8541
| | Posted on Sunday, March 10, 2002 - 7:43 pm: |
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i had one in here about a month ago. i think it is a 2w 30-35ohm resistor.
if that is the case, you can take 3 of the 100ohm 1w res from r.shack (part# 271-152a) and run them all in parallel for a 3w - 33.33ohm resistance. |
Radiodude
| | Posted on Monday, March 11, 2002 - 9:01 am: |
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Sorry ? What do you mean, parallel? |
Ss8541
| | Posted on Tuesday, March 12, 2002 - 12:19 am: |
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side-by-side. you take an end from each resistor and go to the switch. the other 3 ends go to gnd.
that is a good class ab amp. but for am to have good mod, it only needs a 1w carrier input. with a 4w carrier input the amp is almost deadkeying as much as it will swing. |
Radiodude
| | Posted on Tuesday, March 12, 2002 - 9:20 am: |
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Yup it is a very good amp. Ok i got it I will try that. I use it with my Eagle Tomahawk on FM. I have the FM down to about 2 watts |
Radiodude
| | Posted on Tuesday, March 12, 2002 - 9:09 pm: |
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Sorry that didnt work,only have low about 50 watts> thanks anyway any other ideas? |
Ss8541
| | Posted on Wednesday, March 13, 2002 - 12:50 pm: |
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that -is- about what that amp should do in low with a 2w carrier input from the radio. if you want more output, raise the carrier of the radio.
if you are running that amp for fm only then a 4w carrier is about what you need. if for am, then a 1w carrier. |
Radiodude
| | Posted on Wednesday, March 13, 2002 - 10:48 pm: |
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Ok that I agree with BUT it does the same wattage on high. I used to get 150 out of it on high. |
Ss8541
| | Posted on Thursday, March 14, 2002 - 10:32 am: |
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there is only 2 possiblities here, 1), the resistors are soldered to the wrong terminal of the switch, or 2) the switch is bad making the amp stay in low gear. |
Radiodude
| | Posted on Thursday, March 14, 2002 - 5:13 pm: |
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OK I will change the switch and see> Only one pace they could go. lol |
Radiodude
| | Posted on Saturday, March 16, 2002 - 4:56 pm: |
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No still only does 50 watts |
Ss8541
| | Posted on Saturday, March 16, 2002 - 7:38 pm: |
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if you have a multimeter ohm the switch out. if it stays at 0ohms in either position it is bad. |
Radiodude
| | Posted on Sunday, March 17, 2002 - 12:08 am: |
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Hey thanks I will try that and let you know |
Radiodude
| | Posted on Monday, March 18, 2002 - 7:14 pm: |
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Sorry switch is good. I dont need that much pwr now that I have my Melaka so I will use it on low on FM. I hope I can find out what that value is so I can fix it. Anyone got any ideas? |
Ss8541
| | Posted on Tuesday, March 19, 2002 - 9:35 am: |
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radiodude, i know that the value is 3?ohms. you should have a definite jump from low to high with almost any value resistor under 75ohms. since you aren't (staying the same) there -is- a problem besides a resistor of the wrong value.
so i it take it the switch showed 0 ohms in one position and infinite ohms (open circuit) in the other position?? also, are you certain that the other 3 ends -are- soldered to gnd and not something else? . a swamping circuit is a simple circuit. a switch and a resistor. so as you can see there isn't much that can go wrong.
what was your output carrier from the amp b4 the resistors were installed (with old resistor removed)? this will be your actual high power since we know that there is no swamping? |
Radiodude
| | Posted on Tuesday, March 19, 2002 - 6:49 pm: |
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Well thanks and you were right. I found some 1w 100s and put them in as you said and now the amp works fine. Thanks for all the held and I am going to go with till I find out what the orginal part was. |
Radiodude
| | Posted on Thursday, March 21, 2002 - 7:53 am: |
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OOPS well the resistors didnt last long they cooked. I guess I will use it on low till I can get the proper part in it, |
Ss8541
| | Posted on Saturday, March 23, 2002 - 8:34 pm: |
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if the res cooked how are you going to use it on low? the res are what give you low gear.
like i said i know the value is 30something ohms. if you are using a 33ohm resistance capable of 3w and you are only putting 2w across it, then you have a problem in there somewhere. it doesn't matter if you use 1 33ohm 3w resistor or 3 100ohm 1w resistors. you end up with the same thing. and actually since it isn't 0ohms you are putting less than 2w across that load (probably about 1w).
you need to check that switch to make sure that there isn't some type of voltage present with the amp on. if not, you need to -trip- the relay and then see if there is voltage on that switch then. there has to be something there (besides the carrier) drawing excessive current through that resistance. a 2w carrier isn't enough to toast resistors that can hold 3w. even a 4w carrier should be fine. and the fact that it happened so fast and that the original burnt out also shows that something is wrong. -or- you have a bad wattmeter, and you are putting much more than 2w into that amp. these are the only explanations that i can think of.
btw, i'm not trying to bust your ba!!s. i'm just trying to help you. the reason i know that amp has a 30something ohm resistor there is because i am a professional tech. i had a customer in here about a month ago who wanted this same amp matched to a radio with no adjustable carrier. so i played with the swamping value (the 30something ohm res) and when that didn't work out like i wanted, i added a hi/low carrier switch to the radio. |
Radiodude
| | Posted on Monday, March 25, 2002 - 10:33 am: |
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Well I dont know what is going on but the amp works well on low. I dont have anything on high. On low I have about 50 watts ,2w input, and with nothing in the place where that burnt res, was I get 50watts, when I switch to high. I did as you said with the 3 100ohm res and the first time I switch to high, zap burnt. It still works an low but no high. Till I find the orginal part can I just jump the switch? I have some 10ga wire that I can use. I thank you very much for your help |
