I have turned down my 148 to 2 1/2 watts DK going into a RM Italy KL-503 but my audio swings to 15 watts and SSB peaks around 19 or 20 watts. My question is with audio swings this high am I going to smoke the amplifier anyway? It has been like this for close to a year now and the KL-503 runs remarkabley cool also. The KL-503 has 5 power settings on high setting I get 300 watts am with a 250 watt DK now if I turn it down to lets say #2 setting I get aprox 120 watt DK but with audio nearly 300 watts. Would it be safer to run my amp on a lower setting since I nearly get 300 watts anyway? all opinions appreciated. This is all a base set up.
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2 1/2 dead key...15 watts of audio.
- Thread starter hammer0630
- Start date
The specs for that amp says 12w for SSB. Just turn down the ALC a tad until you get about 12-13w with a constant 'ahhhhhhhhh' into the mic. Just because that amp is taking what you are giving it; doesn't mean that it is right for it - nor not putting out a distorted signal. They give those specs for a reason; ya know . . .
Frequency 20-30 MHz
Supply 12-14 Vcc
Input energy/power 12-30 A
Input power 1-6 W
Input power SSB 2-12 W
Output power 250 W Max
Output power SSB 450 W PEP Max
Mode AM-FM-SSB-CW
Fuse 3x10 A
Output power level 6
Size 170x295x62 mm
Weight 1.5 Kg.
Antenna preamplifier 26 dB
EDIT:
You might also turn down the AM carrier to 1 1/2 watts or even go as low as 1/2 watt too; the specs say keep it at 6 watts peak on AM . . . whichever dead key setting will see 6 watts modulating 'ahhhhhhh' is your real target anyway . . . the amp relay should still kick on even with 1/2 watt . . . makes sure your AM modulation is no more than 100% with a continuous 'ahhhhhhhhhh' too . . . this is when having a decent, accurate meter counts - BTW . . .
Frequency 20-30 MHz
Supply 12-14 Vcc
Input energy/power 12-30 A
Input power 1-6 W
Input power SSB 2-12 W
Output power 250 W Max
Output power SSB 450 W PEP Max
Mode AM-FM-SSB-CW
Fuse 3x10 A
Output power level 6
Size 170x295x62 mm
Weight 1.5 Kg.
Antenna preamplifier 26 dB
EDIT:
You might also turn down the AM carrier to 1 1/2 watts or even go as low as 1/2 watt too; the specs say keep it at 6 watts peak on AM . . . whichever dead key setting will see 6 watts modulating 'ahhhhhhh' is your real target anyway . . . the amp relay should still kick on even with 1/2 watt . . . makes sure your AM modulation is no more than 100% with a continuous 'ahhhhhhhhhh' too . . . this is when having a decent, accurate meter counts - BTW . . .
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I'll see just how much I can back it down It kinda seems like I will be bouncing the meter on AM like I was on SSB. I also noticed the specs on the amp are 450 watts SSB a reading I have never been able to hit. My power supply is a Mega Watt something 36 amp constant 40 surge it may not be able to produce that kind
of wattage.
of wattage.
Please explain what you mean by that (bold type)?
If the meter is bouncing around when measuring AM power; did you remember to turn the mic gain all of the way down before you did your testing? That will give you your dead key watts. If it happens after you turn the mic gain down; then there is a bad connections on one of your jumpers.
If that amp is to put out 450 watts on SSB; then a ~50+ amp power supply will have to be used.
Be SURE to adjust your modulation to 100% or less when checking your peak/PEP AM watts. Otherwise, you will just have to go thru the procedure again.
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B
BOOTY MONSTER
Guest
Turn the ssb to 12 watts pep and the am to 10-12 watt peak. The RM/KLV amps are very easy to overdrive and blow up.......VERY EASY!
What I meant by bouncing the S meter is to who ever I might be talking to. If I turn down my 148 to a half watt DK as suggested it would seem I would have a very low carrier and my audio would then greatly increase my power output creating a very noticeable swing forward with audio? Even at 2 1/2 watts DK my own meter (148) bounces quite a bit forward with audio I have had to readjust the meter so it would not continuously bang the needle stop. And thanks for the info on "power supply" My power supply is a Mega Watt-S-400 and I know now for sure it is not big enough. I can not get over 375 watts. I have had my doubts for some time myself. I have wasted a lot of money being cheap on this particular item. Trying to find one big enough which I have
but then had problems with it generating interference. Just a thought I have a Mega Watt 350 and a Mega Watt 400 could these be run together to max the amp output but leave the voltage around 12 volts not 24? Any suggestions on which power supply is good for CB communications one that does not cause interference
but then had problems with it generating interference. Just a thought I have a Mega Watt 350 and a Mega Watt 400 could these be run together to max the amp output but leave the voltage around 12 volts not 24? Any suggestions on which power supply is good for CB communications one that does not cause interference
No, it should not. Any normal, unmodified radio will show much less output on the meter! Now if it has been modified with a swing kit in the radio; then it will swing to full output with a low dead key. If you have a swing kit in the radio and you are trying to hook it up to an amp; then you will have nothing but trouble trying to get the 6w max output. An unmodified radio with a dead key of 1 1/2w will normally swing to ~6w. Been there; done that.
A 1/2w dead key should barely move the needle on key up. Did you check your modulation % so that it is less than 100%? Was the AM Limiter removed? Swing kit installed? Final volted? Stuff like that = not cool if you want to get to that 6w PEP mark. . .
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One of the AM audio limiters was cut and I believe there are more than one but this one I was told only affects AM. This one I was told does not effect SSB as to giving out a "warble" effect when talking SSB and I have never had a complaint either.
Uh-huh; that's what I thought . . .
No; just one AM Limiter in the 148 IIRC.
My experience with SSB 'warble' is that the radio's voltage regulator is being overtaxed by having the ALC level too high. Having the AM Limiter removed will affect the SSB/ALC; it may not warble but it can make it sound like trash because there is no modulation control. This may help to force the 'warble' condition.
Put another AM Limiter back in the radio if you want to tame the output - so you can dial the radio back in the way you want it to be. Will make it more adjustable - so the amp's specs can be realized. You are dealing with an amp that may fry on you eventually if it isn't made 'happy'. The #1 cause of amp failure is too much input to the amp.
IIRC:
Removing the AM Limiter, volting the final, and adding a capacitor/diode is how the NPC mod is done on the 148. That maximizes AM to the detriment of SSB performance. You can still put AM Limiter back in the radio and it will still have some 'swing' to it on AM; but it just won't swing as much. More than enough - maybe/maybe not. AM can be contained and SSB won't suffer - that may solve your dilemma.
Sure there must be WWRF members that remember the finer details and know the 148 better than I do.
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That low carrier and enhanced 'swing' is sometimes called suppressed carrier double sideband. It ain't Kansas (or AM) anymore Toto...
Beginning to wonder if this radio has a different/non-OEM output transistor in it.
Like a IRF-520 maybe?
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This (bold type) is not correct. The AM limiter can be removed in a 148 WITHOUT disabling the SSB ALC. Limiting in AM and SSB is accomplished by attenuating the output of the mike amp. TR24 does this. TR24 is controlled by the AMC sense transistor TR26 in AM, and the ALC sense transistor TR34 in SSB. Removing TR26 defeats AM limiting, but SSB limiting is unaffected. Removing TR24 (which is what most screwdriver jocks do) defeats both AM and SSB limiting.
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