Rm Italy KL-503 watts vs amps

[Slowmover]

And all that for maybe 1/2 of an S unit increase over the kl203.

(This is to the comment. Not the contributor).

Fixed or mobile?

If mobile, an all-metal or a composite-body Class 8 tractor?

There came a point with radio install changes that, on AM-19 skip, if I could hear them, they could hear me. (The 203 wasn’t the amp used).

I’m not trying to be smartass or disagree in principle saying that.

So far as I am concerned, this approach proved out.

Doesn’t make the rig ideal. So?

For about $100 above the price of the 203 I had an amp capable of more than twice the output.

$200 + ship versus $70 + ship (from overseas).

As above, it was the install (and space needed) that put your observation into better context.

FAR more than $100 extra spent in total for a “gain” maybe better addressed elsewhere.

— Didja know that your homeowners policy won’t cover Radio gear installed in a company vehicle?

— Didja know that big trucks are notoriously easy to get into? Limited number of lock/key settings.

As even the approach of better gear in the first place has downsides.

Point is, it’s not just a partial S-unit. It’s also what you’re willing to lose. Had an $80 antenna stolen off my tractor last week. Wasn’t gone four minutes (use a QD for this reason + clearance).

One is boxed in.

Mo powah ain’t wholly dumb truck driver ignorance. It’s a valid approach (given the rest of install problems).

Believe me, there are guys with some HD boxes who don’t click them on till needed. Approaching an exit and the local yahoos won’t shut up. Bam, as time & distance don’t wait on needing a fast answer.

The S-Unit observation needs context.

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[Big Kahuna]

Right on - yeah I did some more testing today and definitely 1 watt carrier is all you need on AM for the KL 7505 then swing up to 200/220.

Definitely a low drive amp - doesn't take much at all and doesn't like to be overdriven. I wouldn't put more than 12-15 watts swing in this one.

Hits 180-200 easily with 10 watts so a good match for any standard single final CB radio. I would not run a KL 7505 with a dual final radio unless you're running on low power and not swinging very much.

 

[2NC995]

12amps or so per 100w output has proven to be reasonably accurate for most CB amps I’ve monkeyed with, assuming modern auto voltage of 14-15v.

This equates to about 60% efficiency.

 

[DudeRanch]

I realize this is an old old thread but I made the following changes to the 503 and its working nicely.
Jumped the fuses with heavy multi strand wires soldered in place.
Do the straight 8 mod as shown on page 3 of this thread. With 20 watts in I'm getting 225 clean out. Very crisp clean audio on SSB.

 

[kopcicle]

So, let's review
30A x 13.8 Volts = 414
414÷2 = 450 watts max PEP on SSB

Had to find out why I was even in this thread ...

 

[Slowmover]

Right on - yeah I did some more testing today and definitely 1 watt carrier is all you need on AM for the KL 7505 then swing up to 200/220.

Definitely a low drive amp - doesn't take much at all and doesn't like to be overdriven. I wouldn't put more than 12-15 watts swing in this one.

Hits 180-200 easily with 10 watts so a good match for any standard single final CB radio. I would not run a KL 7505 with a dual final radio unless you're running on low power and not swinging very much.

Had the DX-99V2 gone thru by DTB Radio a couple of months back. Able to be done as I waited. DK now set at 1.5W. Forgot what he told me the swing was, but I’d guess it’s now lower than 15W. It already needed TLC re being off-frequency, etc. (DK was 2.5W modulate 15W previously).

Guess the DX-99v2 will be the at-home CB from hereon. Have a KL-703 for whatever antenna I figure out. And need a thumper of a power supply.

I’ll get a Galaxy 979 bought around 2016 back up and running to go in the big truck with a KL-7405v. (Protection diode). Bought from Walcott, and re-tuned by Clays. I’ll try to get by Kilgores or Larry’s and get them matched up. The Big Road ain’t gettin’ any purtier. This time it’ll also get a dedicated mic.

The KL-7505v will — tentatively — go into the pickup with the PRESIDENT LINCOLN II. Don’t know if that’ll be a good match or not — don’t know numbers after Walcott “tune”, but it’s yet a ways off before installation. Better antenna system than a big truck to complement the Lincs’ abilities is the idea.

Someday, a high-drive 503.

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[NightThumper]

Yeah baby. You need a high drive KL-503HD for sure dude!

 

[Wayfarer]

I realize this is an old old thread but I made the following changes to the 503 and its working nicely.
Jumped the fuses with heavy multi strand wires soldered in place.
Do the straight 8 mod as shown on page 3 of this thread. With 20 watts in I'm getting 225 clean out. Very crisp clean audio on SSB.

I just placed an order for a KL 503 high drive. I'm going to be running this with a stock Lincoln II+ putting out about 35W PEP SSB. I'm hoping to be able to simply flip the switch on the amp and feed it with 35W to get a clean 250-ishW out and not have to worry about overdriving or having to adjust the power on my Lincoln II+. Is this a reasonable expectation?

Is the high drive version simply a straight 8 version of the regular 503? Has anyone looked inside the HD version to confirm?

 

[kopcicle]

...says right here that it can take 35W input all modes.

Really?

35 what kind of watts ?

I'll quit with the tongue in cheek cuteness and make this easy.

Put an ammeter on the DC input. Put watt meters on the input and output of the (or any amplifier) .

Experiment. It won't go exactly like this but ...

5 watts in 100 watts out 14.4 AMPS 50% efficiency
10 watts in 200 watts out 28.8 AMPS 50% efficiency
20 watts in 400 watts out 57.6 AMPS 50% efficiency

This will not go on for much longer. What happens is you put more wattage in and draw more current but you don't get the expected wattage out.

I remember a member here that swore up and down that his XYZ Magnum (ribbed for HIS pleasure) lineeear amp was doing 600 watts with a 20 AMP fuse. When asked he responded with " it has 2 20 AMP fuses , that's 40 amps , 20 times 40 is 600 "

Every box is different. So I just gently drive them until they don't want any more current or show signs of compression then back off a fair bit to provide a cushion of sorts.

I've owned a Messenger M4V for nearly 25 years. I follow these simple steps and it works, sounds great, lasts forever, and I don't give a rats ass what the output is

 

[Eldorado828]

I just placed an order for a KL 503 high drive. I'm going to be running this with a stock Lincoln II+ putting out about 35W PEP SSB. I'm hoping to be able to simply flip the switch on the amp and feed it with 35W to get a clean 250-ishW out and not have to worry about overdriving or having to adjust the power on my Lincoln II+. Is this a reasonable expectation?

Is the high drive version simply a straight 8 version of the regular 503? Has anyone looked inside the HD version to confirm?

I would think that for the Lincoln 2 you would need the HD instead. Even with the amp off, it's only capable of 50 watts passing through it.

Correct me of I'm wrong but that Lincoln 2 puts out a little too much juice for the non-hd 503.

 

[NightThumper]

The Lincoln 2+ puts out too many watts for the 503HD

My Lincoln 2+ dead keys from 2 to 12 watts. Regardless of the RF power setting the PEP is 55 watts…way to much for the KL-503HD. I’ve got A KL-703 and I won’t dare drive. It with my Lincoln…Only my Cobra 29LTD with 30 watts PEP.

Brad

 

[Slowmover]

The Lincoln 2+ puts out too many watts for the 503HD

My Lincoln 2+ dead keys from 2 to 12 watts. Regardless of the RF power setting the PEP is 55 watts…way to much for the KL-503HD. I’ve got A KL-703 and I won’t dare drive. It with my Lincoln…Only my Cobra 29LTD with 30 watts PEP.

Brad

Which, of course, is a bummer a la the KL-703 as the Junior Ham Radio (Linc) sure would be mobile fun on SSB with some juice.

Was my plan till smoke visions started.

That said, even though I still have the multi-piece factory coax still in use in the Kenworth — the Linc gets out and has a distinctive sound to the audio.

No one asks for repeat of last TX (clarity).

New coax and it’ll have the range TX it does RX on AM (my hope). That 50-55W is good stuff. Main reason I made it the radio choice first go-round versus a pair of Galaxy’s still at home is it’s quality.

But the third choice (G-979) had too much smoke let out. May be toasted. Works . . but.

Might buy another (or 949) to use with the bigger RM amps. Detailed “why” in the t680 thread.

The big truck is sorta the GP Testing Ground.

So, Wayfarer, go sideways.

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[nomadradio]

Why do so many people seem to want the smallest-possible amplifier on the largest-possible radio?

Never ends.

73

 

[Slowmover]

Why do so many people seem to want the smallest-possible amplifier on the largest-possible radio?

Never ends.

73

The Linc has a lower power comparable substitute? Not being a smart aleck so much as wondering aloud.

I might want a more ordinary AM/SSB substitute in the truck, the questioner may want 10/12 Meter. In a mobile radio.

Otherwise, yeah, some packages won’t fit together.

50W is the low end of what works well in a big truck. 100-150W gets the job done better. (Past that doesn’t seem to matter much). Assumes quality install, etc.

 

[Handy Andy]

When asked he responded with " it has 2 20 AMP fuses , that's 40 amps , 20 times 40 is 600 "

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There are Certain Axioms that cannot be disproven...
But...Only when you use the right formulas...​