| Author |
Message |
    
Moonraker
Intermediate Member
Username: Moonraker
Post Number: 175
Registered: 3-2005
| | Posted on Sunday, March 12, 2006 - 4:48 pm: | 
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I have never used or owned a tube-type amplifier but have heard alot about careless people going inside the amp and getting shocked or even killed. What makes a tube amp more dangerous than a transistor? Can you be shocked by touching the upper glass part of the tube while changing them? Some amps I looked at on the net look like the tubes are held in by screws at the base, is this where people get careless and touch high voltage with the screwdriver? And when peolpe "tune" these amps, what exactly are they doing? I think there is a load and a plate adjustment that is "tuned", what do these do?
As you can see I am completely in the dark on this subject and any info will help. |
Wildrat
Advanced Member
Username: Wildrat
Post Number: 825
Registered: 12-2003
| | Posted on Sunday, March 12, 2006 - 10:12 pm: |
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you should only change tubes when there is no power to the box. Both tube and transistor amps can shock the **** out of you. In the tube boxes as well as transistor boxes high voltages are all over the place. The transformers for the power supplies as well as in the varying circuits. Just turn the power off, discharge any capacitors as they store energy. Do it properly though or there will be arcing. Keep your hands away from uninsulated parts of the box and you should be OK. I guess you could get shocked by a tube if you were nuts enough to do it with power on. Some tubes have a wire connected to the top of the tube, there would be voltage there if the unit was powered up. I think maybe what you might be seeing with the tubes that appear to be screwed in, are the screws maybe for the tube socket, or a metal cover over the tube, and that's about all I know. Just don't pull or install tubes with power on and you should be OK. I like tube amps, they are a lot cleaner than transistor amps, and they are not difficult to use, and the tubes will last a very long time as long as they are not over-driven, and the same goes for transistors. Oh well, forgive me if some things don't make sense, I have been on my pain meds hard today. |
Bruce
Senior Member
Username: Bruce
Post Number: 3635
Registered: 9-2003
| | Posted on Monday, March 13, 2006 - 6:59 am: |
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A tube amp .....
1000 watts ..... Plate 2000 volts at .5 amps
You hit the plate lead and you have touched a point at the same voltage as the FLORIDA ELECTRIC CHAIR ...... |
Bullfrog13x4
Junior Member
Username: Bullfrog13x4
Post Number: 17
Registered: 3-2006
| | Posted on Monday, April 17, 2006 - 4:45 pm: |
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this may seem stupid and why would i tell, some one might learn sompthing....
the first tuber i owned was a ldo 500 (same as a skipper 300) and everyone kept telling me do not touch the tubes and like the dumb kid that i was at the time i kept saying why not, no one could tell me and one day i felt the urge. i had a cobra 2000 gtl and a silver eagle and i let it warm up and keyed-up the device and started screaming as loud as i could the tubes were glowing the most butifull bluish purple and with the microphone in one hand and still screaming i grabbed the plate with the other hand, BANG i was shot all the way acrost the room bouncing off the wall on the other side of the room, my arms and hands were shaking for 3 days straight, the amp didnt work any more and the radio was smoking literally, it really hurt. i couldnt even talk right (dadta huma da) that is what my speech looked like for a week.
any way the point is do NOT do this at home luckily i was in need of a regharce and you may not be you mught die!!!!!
hopefully you might find this informative and funny ha ha ha ha !!!!!!! |
Tech291
Moderator
Username: Tech291
Post Number: 386
Registered: 11-2004
| | Posted on Monday, April 17, 2006 - 9:20 pm: |
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Bullfrog,
I dont see the humor in that,you were VERY lucky!
TECH291
CEF#291/CVC#6
KC8ZPJ |
Bruce
Senior Member
Username: Bruce
Post Number: 3750
Registered: 9-2003
| | Posted on Tuesday, April 18, 2006 - 7:14 am: |
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Bullfrog
You are lucky to be alive a friend of mine touched a anode lead on a 4cx250 and 30 years later has no feeling in that hand ....
PLATE VOLTAGES CAN KILL !!!!!!!!!!!!!! |
Bullfrog13x4
Junior Member
Username: Bullfrog13x4
Post Number: 22
Registered: 3-2006
| | Posted on Wednesday, April 19, 2006 - 12:43 am: |
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that is excatly my point.
i am sorry if any of you wer offended by that post, i was trying to point out a potential for the novice to get hurt and hopefully the novice can learn from my mustake and not need or have the urge to try it..
agian i was NOT trying to offend anyone,
bullfrog |
Moonraker
Intermediate Member
Username: Moonraker
Post Number: 194
Registered: 3-2005
| | Posted on Wednesday, April 19, 2006 - 7:07 pm: |
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I can understand how you could get shocked by touching the plate, capacitor or other component. I think I have a misunderstood someone, but was under the impression that you could be shocked by the tube itself (the glass part only) but I can't see how this could be possible and didn't want to learn the hard way. |
Mrhydone
Junior Member
Username: Mrhydone
Post Number: 27
Registered: 7-2005
| | Posted on Thursday, September 28, 2006 - 2:03 pm: |
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Does anyone know if there is a tube tester out
there that can test a 8950 or 2057 tube? |
Akbowtie
Member
Username: Akbowtie
Post Number: 66
Registered: 5-2005
| | Posted on Thursday, September 28, 2006 - 7:54 pm: |
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After doing the same thing as Bullfrog did, with my Skipper 300A, my fingers are not going ANYWHERE near the inside of that puppy when its plugged in and especially when it's turned on.
I was downstairs getting the !@#$ zapped out of me, I thought i was yelling at the top of my lungs and my wife said she never heard a peep out of me.
I now have RESPECT |
Iamwilebill
New member
Username: Iamwilebill
Post Number: 8
Registered: 8-2004
| | Posted on Saturday, October 21, 2006 - 1:31 am: |
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Anybody got any info on a palomar model 150 bi-linear I just got min a pawn shop for 35 bucks. It looks like it's mobile with two power leads on the back. I've always used transister kicker and have no idea how to run it. Does load and tune work the same as an antennae matcher? Thanks. |
Sonny
Intermediate Member
Username: Sonny
Post Number: 112
Registered: 5-2004
| | Posted on Sunday, October 22, 2006 - 2:45 pm: |
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mrhydone, I own a sencore tube checker and have found out the 8950's should be checked as the same settings used for 6LF6 tubes, |
Pogo12
Member
Username: Pogo12
Post Number: 92
Registered: 3-2005
| | Posted on Sunday, October 22, 2006 - 7:08 pm: |
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The 6LF6 tube is a 6-volt tube.I may be losing my memory but I think the 8950 is a 12volt tube.Different filiment voltages. |
Sonny
Intermediate Member
Username: Sonny
Post Number: 114
Registered: 5-2004
| | Posted on Thursday, October 26, 2006 - 8:58 pm: |
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Pogo, you are right 6lf6's are 6 volts thats the only setting that is different you set the volts for 8950's to 11-14 volt setting the rest is the same as 6lf6  |
Pogo12
Member
Username: Pogo12
Post Number: 98
Registered: 3-2005
| | Posted on Monday, October 30, 2006 - 2:53 pm: |
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What makes a tube amp more dangerous is the fact that it carries high DC voltage where as the transistor is low DC voltage but high amperage.Getting shocked by the top of the tube depends on if the plate of the tube(littile silver cap on top) sits on top and if the plate voltage has a direct conection to the powersupply.The plate tunes the output of the tube to the operating frequency.Always tune it for max power output.The load matches the coupling of the amplifier to the antenna.This control should be set to keep the amp in the proper grid range but since in cb amps its not always possible you most likely will have to tune it for max power and then turn it a little to the right which will reduce carrier but it will allow for the extra drive power that is developed with your modulation when you are in AM mode.There is alot of misunderstanding about this control in the cb world.Some people try to whistle and set this control which will work as far as accounting for your extra power by way of modulation but it will reduce carrier too much because people dont talk in a whistle.This is why you will hear alot of people say ahhhh in ther voice as they tune because it gets them a little closer to being more accurate in tuning.The load should be tune for the MAX power the amp will develop with modulation.If you set the drive on AM for 20 watts drive then the most drive it will handle safely PEP is 20 watts.When you dont set this control right you get distrortion/weaken the tubes and in some cases get arching in the tank circuit not to mention splatter to other frequencies.Also dont set the amp meter on front of a amplifier for max deflection to the right.This is not an rf output indicator like your wattmeter. |
Pogo12
Member
Username: Pogo12
Post Number: 99
Registered: 3-2005
| | Posted on Monday, October 30, 2006 - 3:40 pm: |
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I should add to my last post that there are transistor amps that can hurt or even kill you by way of charged filter capacitors not to mention that the high amperage isnt safe either.The moral is stay out of amplifiers unless you know what youre doing. |
Road_warrior
Senior Member
Username: Road_warrior
Post Number: 2012
Registered: 7-2004
| | Posted on Tuesday, October 31, 2006 - 1:28 pm: |
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I found humor in it Bullfrog.
And you also relayed a good message for
people to keep there fingers out of
anything that's is plugged in. Esp
a tube amp! |
Road_warrior
Senior Member
Username: Road_warrior
Post Number: 2013
Registered: 7-2004
| | Posted on Tuesday, October 31, 2006 - 1:33 pm: |
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Guess, i should add even a unplugged amp
should not be touched unless you know what
your doing. Some parts still hold a charge
even though turned off or unplugged. |
Mrclean
Junior Member
Username: Mrclean
Post Number: 43
Registered: 12-2003
| | Posted on Monday, November 06, 2006 - 8:47 pm: |
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I had a 100 watt footwarmer when I was 11 or so. I was so smart I stuck a butter knife in the case to move the coil away from the cabinet abit. It threw me acrossed the room and I could smell burning flesh. Smart kid! |
