RM KL503 - Is it any good on SSB?

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MiXiN
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RM KL503 - Is it any good on SSB?

Post by MiXiN »

I'm thinking about getting a KL503.

Can anyone current or ex owners tell me if these sound any good on SSB?

Also, are they reliable if not over driven?
Edd200sx
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Re: RM KL503 - Is it any good on SSB?

Post by Edd200sx »

They need a mod doing usually for ssb as they warble like
Boris Johnson
MiXiN
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Re: RM KL503 - Is it any good on SSB?

Post by MiXiN »

Edd200sx wrote: 29 Jul 2021, 20:21 They need a mod doing usually for ssb as they warble like
Boris Johnson
Oh dear, that's not good.

Do you know what the mod' is, and do you know what class operation the KL503 is?

I was hoping the SSB audio would be pretty good as per the KL203.
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Re: RM KL503 - Is it any good on SSB?

Post by Edd200sx »

Add 12pf to C34 I believe

You’d have to double check online
MiXiN
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Re: RM KL503 - Is it any good on SSB?

Post by MiXiN »

Edd200sx wrote: 29 Jul 2021, 21:15 Add 12pf to C34 I believe

You’d have to double check online
After a bit of looking around, the mod you mention is to prevent the relay chattering on SSB.

I'll keep looking around.
Edd200sx
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Re: RM KL503 - Is it any good on SSB?

Post by Edd200sx »

MiXiN wrote: 30 Jul 2021, 06:41
Edd200sx wrote: 29 Jul 2021, 21:15 Add 12pf to C34 I believe

You’d have to double check online
After a bit of looking around, the mod you mention is to prevent the relay chattering on SSB.

I'll keep looking around.
It is indeed. You’d have to build a thermal reactive + adjustable bias into it
As the bias being low can obviously cause warble
MiXiN
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Re: RM KL503 - Is it any good on SSB?

Post by MiXiN »

Last minute decision, but I decided to amend my order & go for the KL505 instead.

Not sure if I've made the right decision or not?
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Re: RM KL503 - Is it any good on SSB?

Post by Edd200sx »

MiXiN wrote: 30 Jul 2021, 16:16 Last minute decision, but I decided to amend my order & go for the KL505 instead.

Not sure if I've made the right decision or not?
Definitely! I’ve got a 505v it’s nearly 4 years old never missed
A beat
MiXiN
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Re: RM KL503 - Is it any good on SSB?

Post by MiXiN »

Edd200sx wrote: 31 Jul 2021, 00:12
MiXiN wrote: 30 Jul 2021, 16:16 Last minute decision, but I decided to amend my order & go for the KL505 instead.

Not sure if I've made the right decision or not?
Definitely! I’ve got a 505v it’s nearly 4 years old never missed
A beat
That's good to hear.

I bought the 505 without the fans, as I've got some decent Artic Cooling 120mm fans here.

I notice that the 505 also uses good old fashioned Bipolar Transistors as opposed to Mosfets as used in the 503, so the 505 will be more robust.

What sort of power are you seeing from yours with what drive, please?
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Re: RM KL503 - Is it any good on SSB?

Post by Edd200sx »

6/7w drive 200w out fm
MiXiN
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Re: RM KL503 - Is it any good on SSB?

Post by MiXiN »

Edd200sx wrote: 01 Aug 2021, 09:36 6/7w drive 200w out fm
Tested mine last night, and I see 4W in = 150W out, 5W = 180W, 6W = 200W, and 7W = 220W at 32A draw.

I only keyed for about 10 seconds at 7W as I bottled it.

What's the maximum drive you give yours bud?
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Re: RM KL503 - Is it any good on SSB?

Post by Edd200sx »

I think 10w is about 230/250 on a dubious meter

I’ll have to plug it into my fx775 vector meter
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Re: RM KL503 - Is it any good on SSB?

Post by QRZ-934 »

No issues with mine at all once I worked out it needs a good psu to drive it.
I run it on ssb mode all the time, dont even change the switch for fm/am op seems to work fine with great audio reports so far.
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Re: RM KL503 - Is it any good on SSB?

Post by gmham »

Raising an old thread there guys but you still recommend the kl505 out of the current breed of Italian amps ? Looking for one just now if anyone knows of one going ?
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Re: RM KL503 - Is it any good on SSB?

Post by prettypolly »

Rm kl703 35 watts in no1 setting 200 out no 2 setting 350 no 3 setting 475 watts out
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