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707
| | Posted on Sunday, July 29, 2001 - 2:11 pm: | 
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Okay...I finally did it...
My "medical research laboratory" reeks of vaporized semiconductor. Has anyone found a suitable replacement for the KL-40 output transistor? Maybe one that doesn't explode at EXACTLY 12 watts :-)
The thing ran fine on one radio I had set to put out 10w PEP ssb, but, curious experimenter that I am, I hooked it up to a "Real CB", doing 12w PEP, keyed up with speech processor on and mic gain wide open, I got about 5 words out and "SSSSPPFFFFFT!..... |
Tech181 (Tech181)
| | Posted on Sunday, July 29, 2001 - 5:37 pm: |
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707,
I didn't even get out 5 words...
I think I will research this though. I will try to find a source for transistors that can take a little more without compromising the internal components of the KL40. Give me a few days and I will post what I find out.
Steve
Tech181
Tech181@copperelectronics.com |
Anonymous
| | Posted on Sunday, July 29, 2001 - 9:49 pm: |
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These amps are designed to run off 4 watts on the average, overpowering them does not work. |
Copper_Fan
| | Posted on Tuesday, July 31, 2001 - 7:16 pm: |
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18 watts from a StupidStar3900 = POOOOOOF!!!!! |
Jerry Bryant
| | Posted on Sunday, September 02, 2001 - 6:08 pm: |
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I put 35 watts P.E.P.into a KL-40 for short intervals [before it got real hot] and it survived for two weeks.I'm also looking for a replacement transistor for the RM3.Possibly one which I can drive harder too. Hey,we've given the KLV company something to work on in the future:high drive single transistor amps.J.C.B. |
Jerry Bryant
| | Posted on Thursday, September 06, 2001 - 2:46 pm: |
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Tech 181, any news yet on a transistor that is more rugged than the RM-3 MOS transistor? I'm going to ask my local radio shop and see if Screwdriver and Digger know of a better replacement also.I was also wondering if you could get more power from this "little red cigarette pack size amp" by adding more RM-3 transistors to it. J.C.B. |
Tech181 (Tech181)
| | Posted on Thursday, September 06, 2001 - 6:15 pm: |
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Jerry,
I tried to find a suitable replacement. That's not a problem. The problem is finding the manufacturers specs on the existing transistor to match something up with it. Even if you did, $20-30 is too much money to spend on a transistor for a $40 amp.
Copper has the original factory replacement transistors for the KL-40 for $7.50.
Add more transistors to it? Perhaps, but I noticed that the KL-40 can just barely handle the heat from one. I had a resistor keep coming unsoldered when I used mine for a considerable amount of time.
I think the biggest thing to remember with this amp, and I think others here can back me up, is to go real easy on the input power. This is what has caused all the premature failures in these amps.
As a matter of fact, I wouldn't recommend using the KL-40 with any dual final radio at all. The power output is just too high. You can adjust your radio down to work with this amp, but what's the point? Most export radios will run upwards of 30 watts PEP anyway.
Don't get me wrong, this IS a GREAT piece of equipment. You just can't keep feeding it with a lot of power for any length of time.
I found that 1 1/2 watts is all you need to make this amp work well. At a 1 1/2 watt input my dead key was 14 watts and swung well past 30 watts.
Steve
Tech181
Tech181@copperelectronics.com |
Dawg
| | Posted on Sunday, December 30, 2001 - 12:07 pm: |
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I bought one of these little amps and have fabricated a couple of brackets out of aluminum sheet metal that attach to the bottom fins via 1/8 inch screws. I drilled holes throught the fins and then tapped them being very careful not to get into the side of the amp. Is it ok to mount this on top of my PC68LTW ? I have 2 1/2 inches between the components.The radio is brand new and stock. My mini 8 jumper is three feet long. Is it ok to coil the jumper to make this all a nice tidy package that can be quickly uninstalled in my pick up ? |
Vernonott
| | Posted on Sunday, December 30, 2001 - 5:49 pm: |
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Dawg:I've always had problems when mounting amplifiers close to the radio.It may work for you but hasn't for me. |
Dawg
| | Posted on Sunday, December 30, 2001 - 7:33 pm: |
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Vernonott: Would this cause the transmission to distort, squeal, be muffled, all of the above or what? It is such a small amp I doubt there will be any heat. I don't know a thing about electromagnetic fields or anything, whats the deal? |
Highlander1588
| | Posted on Sunday, December 30, 2001 - 8:36 pm: |
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DAWG, I wouldn`t reccomend coiling the coax it can cause a choke effect in the line. That is what I have always been told and have not tried otherwise to prove it wrong. |
Dawg
| | Posted on Sunday, December 30, 2001 - 10:26 pm: |
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Thanks guys for the help! |
bruce
| | Posted on Sunday, December 30, 2001 - 10:59 pm: |
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The problem is rf comming BACK down the coax. Coiling it will help sometimes but the BEST way is to install ferte beads on the coax AT the antenna. AS for muffled this amp goes non liner at about 3 watts so keep the drive below that it will work just fine |
Dawg
| | Posted on Monday, December 31, 2001 - 9:51 am: |
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TECH 181,Help!! I have some guys saying it won't hurt to coil the jumper, some say it will, another talking about some kind of beads,the forum master in his review of this amp saying you could mount the amp on top of the radio, and others saing you shouldn't. I don't want to drill holes in a brand new pick up to mount the little amp, the console has an area with 4 cup holders and this is where I kept my last radio and it worked great. I need to be able to take the radio and amp out quickly and easily to protect against my windows being broken out and my equipmernt stolen. Sad to say but it is a fact of life in the city, people will do bad things for a 20 dollar rock of crack and in broad daylight. |
bruce
| | Posted on Monday, December 31, 2001 - 5:24 pm: |
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dawg the problem is your not keeping rf from comming down your coax
1) make sure you have a GOOD ground AT the antenna
2) if a good ground is a problem get a copy of the ARRL handbook and read up on balums using beads they are very good over a wide frequency range.
3) you can mount your amp anywhere you want PROVIDED your coax between it and the radio is sound.
4) i have one ( amp ) i use it for 10 meters and i use a second on 2 meters running over 100 watts on that band NEITHER has a problem
radio-doctor@juno.com
bruce |
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