Copper Talk » Ask The Tech » Amplifiers » (2) SD 1446 or (4) MRF 455's?? « Previous Next »

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Outkast
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Username: Outkast

Post Number: 82
Registered: 9-2005


Posted on Monday, November 07, 2005 - 3:16 pm:   Edit Post Delete Post    Move Post (Moderator/Admin Only)

I was looking at a couple diffrent KL amps and noticed that there is a KL 500 and a KL 500 24 they have the same power output here are the specs:

KL 500 24 using (4) MRF 455 Transistors
Frequency: HF
Input energy/power: 5-16 A
Input power: 1-10 W
Input power: SSB 2-20 W
Output power: 300 W Max
Output power: SSB 600 W pep Max
Mode: AM-FM-SSB-CW
Fuse: 2x8 A
Output power level: 6
Size: 170x295x62 mm
Weight: 1,4 Kg.
Antenna preamplifier: 26 dB

KL 500 using (2) SD 1446 Transistors
Frequency: HF
Input energy/power: 10-34 A
Input power: 1-15 W
Input power SSB: 2-30 W
Output power: 300 W Max
Output power SSB: 600 W pep Max
Mode: AM-FM-SSB-CW
Fuse: 3x12 A
Output power level: 6
Size: 170x295x62 mm
Weight: 1.6 Kg.
Antenna preamplifier: 26 dB

So which one would give cleaner power? Are there any draw backs from one to the other? Which one would be the better one to go with? And whats the point to having the same basic amp with two diffrent transistor options?

Outkast

CEF 650

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Patzerozero
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Username: Patzerozero

Post Number: 1855
Registered: 7-2004


Posted on Monday, November 07, 2005 - 6:57 pm:   Edit Post Delete Post    Move Post (Moderator/Admin Only)

the 455's are rated @ 60 watts each, so times 4=about 240 watts PEP & MAYBE 60 watts dead key.

the 1446's are rated @ 90 watts times 2=about 180 watts PEP & about 45 watts dead key.

the day you see REAL 600 watts out of either...

the 1446's SHOULD handle the input of a standard dual final radio, or at least a bit more input then the 4x455 model. you still need to start with LOW input & see where it sounds best.

the 4x455 model also appears to draw less current & may be easier to power in a small car or with a power supply at a base.

wattage figures are estimates, but in no way shape or form is it EVER gonna get you anywhere near 600 watts, no matter what the brochure-or wattmeter-says.

the 1446 model would be the preferred model. i would almost BET side by side it'll make the radio sound LOUDER & probably be REAL close to the other model in output.

without having looked at rmitaly's website in a long time, i can only guess it's due to transistor availability...
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Yankee
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Username: Yankee

Post Number: 993
Registered: 7-2003
Posted on Tuesday, November 08, 2005 - 9:48 am:   Edit Post Delete Post    Move Post (Moderator/Admin Only)

He He
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Hotwire
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Username: Hotwire

Post Number: 693
Registered: 1-2005
Posted on Tuesday, November 08, 2005 - 12:14 pm:   Edit Post Delete Post    Move Post (Moderator/Admin Only)

My little mobile amp uses 2 of the 1446 transisters. Been using it a while now with no problems and always get good reports. My 148 swings 20 watts with strong modulation into it and is really pushing the amp to its limits. Much over 20 watts most likely would start to make the audio kinda crummy. Best to turn mic gain down low.
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Outkast
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Username: Outkast

Post Number: 84
Registered: 9-2005


Posted on Tuesday, November 08, 2005 - 12:59 pm:   Edit Post Delete Post    Move Post (Moderator/Admin Only)

Hey Pat would the rated power you said for the 1446's be on AM or SSB? So the KL max output on AM would be 180?!?! If so wow thats a screw of a deal. LOL

Outkast

CEF 650
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Yankee
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Username: Yankee

Post Number: 994
Registered: 7-2003
Posted on Tuesday, November 08, 2005 - 3:08 pm:   Edit Post Delete Post    Move Post (Moderator/Admin Only)

OK, I wasn't going to say. But the most I've seen with a pair of 1446s is 150-165 watts sideband, need to remember the 1446 is only a 90 watt transistor.
I don't operate a lot of AM, but around 100-120 watts AM.
Drive power from the radio, no more than 3-4 watts AM dead key, if you want the amp. to last a few years.
Takes a pair of transistors a whole lot heavier than a pair of 1446s to do 300 watts.
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Dd18
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Username: Dd18

Post Number: 61
Registered: 11-2004


Posted on Wednesday, November 09, 2005 - 5:16 pm:   Edit Post Delete Post    Move Post (Moderator/Admin Only)

Read the specs....the KL500 24 is a 24 volt amp for trucks with a 24 volt system.
That's all...no magic
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Outkast
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Username: Outkast

Post Number: 89
Registered: 9-2005


Posted on Thursday, November 10, 2005 - 12:07 am:   Edit Post Delete Post    Move Post (Moderator/Admin Only)

Hmm now I wonder how I am possibly doing 180 watts on SSB with a single SD 1446 in my KL 200p? Can the two meters I have used with this amp possibly be that far off? My Rat shack meters says just a little over 170 watts and my buddys Dosy reads about 185 watts, yet they both read the same 80 watts on AM. So how is it doing this then if that is alomost what a radio with two of the same exact transistors would do?

Outkast

CEF 650
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Chad
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Username: Chad

Post Number: 559
Registered: 11-2004


Posted on Thursday, November 10, 2005 - 9:06 am:   Edit Post Delete Post    Move Post (Moderator/Admin Only)

How much current is it pulling? (KL200P)

My KL300P makes at best 150W AM and a very lucky 200 on SSB, that's pushing it. I have found it does best and is cleanest making no more than 100-120W in any mode. I give it 14.4 solid volts. It can do a tad more but I see no reason to push it as 100W seems to be enough if not too much to establish good contact. I always try the Magnum 257 Barefoot first, and it does very well. Actually SOUNDS better without the amp on the other end. I think I need to mod it for class AB operation.

Chad
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Outkast
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Username: Outkast

Post Number: 90
Registered: 9-2005


Posted on Thursday, November 10, 2005 - 5:16 pm:   Edit Post Delete Post    Move Post (Moderator/Admin Only)

Chad as far as amperage I dont know what it is pulling, it has a 20 Amp fuse in it and hasn't blown it yet. But it is being fed a bit more than your 14.4 my voltage regulator in the car allows 15.7 volts and when I key the little guy it drops down to about 13.9 volts at the battery. I have not heard mine more than 20 miles away but at that distance it sounded very clean and healthy.

Outkast

CEF 650
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Patzerozero
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Username: Patzerozero

Post Number: 1863
Registered: 7-2004


Posted on Friday, November 11, 2005 - 6:57 pm:   Edit Post Delete Post    Move Post (Moderator/Admin Only)

makes sense Dd18 like i said, haven't looked at their site in a while, had i, i MAY have seen that . not much need for 24 volt equipt here so...

it's a 90 watt transistor with no real engineering magic performed on it. little tiny transformers, no rfi coils....ahhh, try a tvi filter on it & wattage should decrease some...keep the input LOW & signal will clean up & bleedover will be reduced. bang for the buck, kl amps are not a bad deal, just expect reasonable real world output, not overhyped BIG #'s.

class C MAY show more PEP on AM then SSB, but the 90 watt rating IS 90 watts PEP, about 22 watts dead key RMS & maybe 50 RMS swing. class AB/AB1 MAY reduce ALL output somewhat.

a volt or 2 is not going to increase output. around 18 volts is where wattage starts to increase. if amp is NOT designed to handle the high voltage, smoke & fire increases & watts immediately go to ZERO.

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Bigbob
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Username: Bigbob

Post Number: 2255
Registered: 12-2001
Posted on Sunday, November 13, 2005 - 7:17 am:   Edit Post Delete Post    Move Post (Moderator/Admin Only)

One thing that RFPARTS says in their catalogue the rf transistors are rated for AM and FM and typically produce 50% more on SSB and CW,so a 90 watt would be 135 on ssb,so take that one step further 2x135=270 or very close to 300,but that's it,and no you won't see this with any meter you need a SCOPE!!!Bigbob
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Patzerozero
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Username: Patzerozero

Post Number: 1877
Registered: 7-2004


Posted on Sunday, November 13, 2005 - 11:31 am:   Edit Post Delete Post    Move Post (Moderator/Admin Only)

i've already been through this with rf parts:

1. they rate the sd1446 at 70 watts carrier, in FM @ 28 mHz.
2.they rate the sd1446 at 90 watts PEP on SSB @ 28 mHz.
3.they do NOT rate it at carrier on AM @ 28 mHz, BUT, typically, carrier of 25% is expected, thus 22 watts RMS.

points 1 & 2 ARE printed in their catalog & WAS confirmed with them by phone. point 3 is NOT printed in their catalog so it WAS confirmed by phone.

as for RATINGS...that is where the manufacturer decides their product works at its BEST, where they are willing to warranty it. obviously, if they rate it at 12 volts to provide 90 watts, that is NOT the max it will do. they give it some breathing room. the commercial amp builders, who are already not exactly operating within the law, build the amp to within that transistors' suggested operating limits. though they overrate their product, they do not overbuild it, so as to leave it on the edge of self destruction continually. and leave them open to complaints from customers & possible attention from the wrong parties. the custom builders take their time & overbuild matching network & combiner networks to allow these amps to use more available voltage & PEP input to provide greater PEP output. RMS output can only be increased minimally at the same voltage. they use 2879 transistors in high voltage systems because of its ability to withstand 22-24-28 volts. that is when they produce DOUBLE their output ratings. their lifespan is also decreased as well.
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Cuda64
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Username: Cuda64

Post Number: 2
Registered: 2-2006
Posted on Wednesday, February 08, 2006 - 2:19 am:   Edit Post Delete Post    Move Post (Moderator/Admin Only)

yo the kl 500 ha 4 1446 in it i have one
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Im4jc
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Username: Im4jc

Post Number: 88
Registered: 11-2005


Posted on Wednesday, February 08, 2006 - 1:16 pm:   Edit Post Delete Post    Move Post (Moderator/Admin Only)

Hotwire: Your 148 swings 20 watts PEP into 2 1446's? What's the DK set at on the 148?

I have my Grant doing 2.5 key and 12 watts pep into 2 1446's because I'm afraid to push the amp any higher. It gets me an amp key of 33 watts and swings about 175.

If I could get away with it I'd really like to key around 4 watts so that I sound better when running barefoot, but I've heard that this will smoke the 2 1446's, not to mention that I'm also afraid that it will sound dirty.

I don't have any accurate meters, so I have to pay my tech to make the adjustments. Otherwise, I'd be experimenting myself.
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Patzerozero
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Username: Patzerozero

Post Number: 2401
Registered: 7-2004


Posted on Wednesday, February 08, 2006 - 4:34 pm:   Edit Post Delete Post    Move Post (Moderator/Admin Only)

set the radio so the amp dead keys 25% of the rated output of the transistors. (i have spoken to rf parts regarding their double listing of 1446 specs, & they seem to feel it is more safely rated at 70 watts for 27 mHz use, though in different uses, it is rated at 90). SO, if you wanna use the 70 watt #, it would be 2 x 70= 140,divided by 4=35 watts dead key, OR 2 x 90= 180 divided by 4= 45 watts dead key.

since you're already at 33, gradually increase the radio dead key til the amp dead key goes to 40, then 45 & see how it sounds. if 45 is good, use it hard, watch for heat, & you may wanna even live dangerously & try it at 50. i've found 33% dead key is USUALLY an OK #, if you keep heat down-fans, etc. that would be a 50-60 watt dead key with 2 x 1446.

my XL has variable wired into the squelch, & i turn it all the way down, amp all the way up, key & adjust variable til amp is where i want it. then let it fly .
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Im4jc
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Username: Im4jc

Post Number: 93
Registered: 11-2005


Posted on Wednesday, February 08, 2006 - 5:00 pm:   Edit Post Delete Post    Move Post (Moderator/Admin Only)

Rog-e-oh. I'm just going to have to break down and get a meter to run inline all the time. Maybe the RatShack? Once I get it, I can make the adjustments myself without nickle-and-diming myself to death at the local CB Shop.
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Bronzepony
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Username: Bronzepony

Post Number: 79
Registered: 12-2005
Posted on Saturday, November 18, 2006 - 8:18 pm:   Edit Post Delete Post    Move Post (Moderator/Admin Only)

Have done some testing on this a 2-pill 455 amp.
If you have it keying over 30 it will swing backwards. This was on a doesy in rms and a bird 43.
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Caledonia
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Username: Caledonia

Post Number: 25
Registered: 8-2005
Posted on Sunday, November 19, 2006 - 7:57 am:   Edit Post Delete Post    Move Post (Moderator/Admin Only)

Chad, the Inspector (a copper forum member) once posted a mod for making the KL-300 an AB amp. It was a real simple circuit, no thermal tracking or anything fancy, but it made it acceptable for SSB.

That's something I've never understood about the marketing of the KL mobiles--only the KL-400 and the KL-500 are AB, the rest are all C. But they market them as if they are OK for SSB (Just because it has a delay, I guess.)

I think it should be made clear which models are class C and which are classs AB. Posting a review saying that they are great on SSB is a disservice to the buyer!

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