kl203p- new version ?

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gmham
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Re: kl203p- new version ?

Post by gmham » 01 Jan 2018, 17:23

Black Spirit wrote:
01 Jan 2018, 16:33
ch25 wrote:
01 Jan 2018, 15:07
Mudslinger wrote:
01 Jan 2018, 14:51
I normally put around 7 watts AM/FM and 18Watts SSB into mine and have had no issues.
You just have no idea of amout of garbage going out when you overdrive that box. Lucky, I do not have you in the neighbourhood.
Finally, Someone who agrees with me that the KL203 [MOSFET] is an awful amp, Just by seeing the SWR jump when powered on indicates the amount of rubbish being spewed out of them, I dont have the pleasure of owning a spectrum analyser but i would love to see the results of a KL203 with 5-15w input.
Not sure if it's ch25 you are referring to in your reply nick regarding just how bad these amps are as yes he does say
""
You just have no idea of amonut of garbage going out when you overdrive that box. Lucky, I do not have you in the neighbourhood.

But also earlier says "


kl203 works acceptable as long as you do not exceed 2W AM/FM and 10-12 SSB on input. Looks not that bad on the scope and spectrum analyser.
More drive, more distortion. Tested by myself.
Chris

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Re: kl203p- new version ?

Post by wa10 » 01 Jan 2018, 18:50

We have talked about RM Italy's mickeymouse drive levels multiple times in the past,

RM italy FLAT OUT LIE about their amplifier input & output ratings,
the amps make LOTS of distortion burn power sellector & feedback resistors & eventually fall apart at RM italy drive levels, people keep buying them, overdriving the snot out of them, blowing them up, buy another,

some people ignore the truth , even tell newbies asking about drive levels that its ok to input stupidwatts because RM say so,


1/2 of what RM say is ok is still WAY beyond the 1db gain compression point for the kl203, running anything like 20w into kl203's is crazy with a squashed undynamic overdriven sound.

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Re: kl203p- new version ?

Post by gmham » 01 Jan 2018, 19:28

Yep okay thanks for your input on the subject, so not 100% ideal but 10 watts to 12 watts ssb pep is the very max you would suggest running into the kl203p
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Re: kl203p- new version ?

Post by wa10 » 01 Jan 2018, 22:23

10w is the most i would drive a 203 with, that's well into gain compression but still sounds reasonable on ssb, 12w peaks won't hurt it,
if you run compression/clippers/mics that increase average talk power id turn the drive down below 10w,

The heatsink is way too small for the output, 80mm fan with a small hub fits just right & keeps them alive.

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Re: kl203p- new version ?

Post by gmham » 01 Jan 2018, 22:35

okay thanks again any idea what 10watts input would likely give out ?
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Re: kl203p- new version ?

Post by ch25 » 01 Jan 2018, 23:02

Square wave.
You can't have too many antennas...

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Re: kl203p- new version ?

Post by 108EH002 » 01 Jan 2018, 23:23

Meant to be upto 10 × what you put in like the old ones,but they are not.No more than 4-5 on am/fm and upto 10w on ssb,they seem to last at that for many years,but I have run it higher,and its 6 yr old and used everyday,but only for the pre-amp ;)
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Re: kl203p- new version ?

Post by wa10 » 02 Jan 2018, 12:12

Output for kl203's 10w drive varies or i should say what they show on a meter varies, they are not all the same they use switching fets not designed for RF linear amplification,

last one i had (indicated) 122w on my lp-100 & bird load, some won't show more than 100w with the same drive, sure you can make them indicate more on a watt meter by driving it harder/closer to a square wave generator or running the supply voltage higher,

when you beat the **** out of amplifiers like that they get nasty & the watt meter loses the plot, driving amps like that gives Meterbaters a hard on like rubber & handcuffs,

around 4w drive is where serious gain compression sets in, a real amp maker would stop before this point,

10w is hammering them far above the 1db gain compression point often used as a benchmark, well beyond any resemblance to a linear amplifier,

10+ -20w drive is past the Meterbaters warm fuzzy feeling "my amp does more than yours" point & very close to smoke.

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Re: kl203p- new version ?

Post by Phoenix » 02 Jan 2018, 14:20

I really like all the RM stuff for what they are....They all need under driving and they all need fans fitted. Enjoyed the thread and the technical explanations.Cheers guys
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Re: kl203p- new version ?

Post by astradyne » 03 Jan 2018, 01:02

I have a couple of RM amps. The KL400 which I use for mobile. I've used it for a couple of years now and not had any problems. I've never put more than 8W in on FM and 14-15W SSB. I've put a fan on the top and left the backplate off to help with cooling.

The other RM is KLV550. Hell of an amp this one. I get around half a kilowatt out on SSB with a 20W input and around 300W FM with 8-10W input. Superb tuneable pre-amp too
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Re: kl203p- new version ?

Post by wa10 » 04 Jan 2018, 10:44

That's about double what you should input into both amps Andy, far beyond linear,

i own 2 kl550's & worked on a few for other folk, early versions had a pair of mrf422's, 150w @28volts later versions had higher gain less durable sd1407's 125w @28v,

The 550's psu is unregulated they start at around 30v off load & droop to 25v or less @10w drive,
you are 3 volts short of the test circuit voltage with only10w drive & a less efficient impedance matching setup than the single ended test circuit,
the harder you drive it the worse it gets,

300w is overdriving a 550, half a kilowatt is fooling the meter aka Meterbating,

Anybody interested in understanding how much RM lie about power rating can read this article from Tom Rauch. the hla150 is a kl400 with filters.

https://www.w8ji.com/rm_hla-150_test.htm

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Re: kl203p- new version ?

Post by MiXiN » 05 Jan 2018, 02:11

So, in a nutshell, is 5W OK to drive an RM KL203P for longevity or will it die prematurely?

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Re: kl203p- new version ?

Post by wa10 » 05 Jan 2018, 09:32

Yes its ok for longevity.

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Re: kl203p- new version ?

Post by pienari » 10 Jan 2018, 12:23

I have made 6fet mods for v5 and v6 red ones.
FM.
Standard. 13.8v 10w in 90w out.
Moded.
13.8v 10w in 105w out.
15v 10w in 120w out.
15v 15w in 140w out.
17.7v 22w in 185w out.


Totally not linear with fet..
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Re: kl203p- new version ?

Post by gmham » 13 Jan 2018, 18:20

Guys did you wire in the additional fan so it comes on and off with the amp itself or just wire separate ? Much involved in fitting one off the temp sensor units to just have the amp on when it reaches a certain temp ? Is it necessary or advisable to change the red / black wires to something a bit more heavy duty ?
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