More Idiotic Fet Amp's Can Wild or Mad.....LOL

[Onelasttime]

Ok so according to Lester's own meters and video we have a KL Stinger in radio doing 30 watts rms swinging to a peak of over 150 watts!!! At most it should be swinging to 120 watts if we observe the 4:1 rule!

On top of that we have an audio compression SP1-a device that is going to increase the average audio level and thus the duty cycle that the amp see's when they are both on.

Can you say recipe for short life span????? If that was setup to key 20 and swing to 60 assuming it never say a high swr it would last forever. If was set up to maybe max out with a 25 watt key swinging to 100 it would last a lot longer.

If it was set up with a nice variable rf power tuned for a max of 25 carrier swinging to 100 and the owner ran the rf power at the 12 O'Clock setting again it would last forever.

I understand the amp has an on off switch but who wants to have a system where it is all or nothing?Imagine operating your car that way either off or at WOT.....LOL

He obviously know's this amp should not be outputting this much power he even says as much in his own video so why would anyone let it leave their shop like this?

I am sure we will hear this radio splatering all over the place at some point. Too bad radio's did not broadcast an " I am a splatter box" coded signal on one of the many sub carriers they generate to let everyone know! LOL Even better if they identified the name of the tech that worked on them!

 

[sonoma]

I put the kl stinger board in a galaxy 44 and it only does 100 watts max with a whistle into the mic.would not want it to do any more myself. normal talking it does about 65 to 70 watts. that is plenty for me. forgot to mention my 44 is the single final radio.

 

[9C1Driver]

What finals are they running in these new Stinger boards? Used to be a single 1446, then variations had the ERF7530. Just curious.

 

[Tallman]

The KL stingers use the RM3 FET which is easily replaced by the better IRF type of FET.

 

[magnuman]

The KL stingers use the RM3 FET which is easily replaced by the better IRF type of FET.

I have found the FET that RM is using is a little better than the IRF 520 that frequently gets substituted when the RM3 gets overdriven and dies. RM file off the markings so hard to know exactly what the RM3 really is.

 

[Tallman]

I have found the FET that RM is using is a little better than the IRF 520 that frequently gets substituted when the RM3 gets overdriven and dies. RM file off the markings so hard to know exactly what the RM3 really is.

Yes I know that. It is actually sanded off. I have been working on those amps for quite a while. The IRF510/520 is just the nearest commercially available part electrically to the RM3. I will have to check the RDS on spec to see which one is the closest to the RM3 if I still have any left in stock.

 

[Robb]

Hmmmm . . . maybe a 13n10 perhaps?

 

[sonoma]

I use the 13N10 fets for those little amps also. most will put out just a little more than the RM3 fets they put in them. at least what few I have done ups output a little. I have used them in 2 of the galaxy radios that has the amp board in it that uses 8 fets.have not had any to blow up so far. they run good in the cobra 29 radios also.

 

[Tallman]

I use the 13N10 fets for those little amps also. most will put out just a little more than the RM3 fets they put in them.

It has been a while since I was up in my radio shop and went up to test the RDS of the RM3 fets. I had none so I can't test the RDS on of the RM3. But I had been using the 13N10 fets to fix the KL-203 amps. I used those13N10's and discovered that the power feed wires for the KL-203 was insufficient and required an upgrade to a larger gauge wire. The signal was flat topping on the positive peaks and the heavier wire fixed that.
The voltage drop was quite noticeable until the heavier wire was in place. The leds dimmed when the amp was dead keyed with 1 watt.

 

[M0GVZ]

I wonder how much of that 100+ watts is actually being transmitted on the 3-6kHz you want it to be and how much of it is being wasted as harmonics and splatter.

A power meter will only show you the total combined power it measures, not where it is going.

 

[Tallman]

I have checked the KL-203 and as long as the input is clean the output will be as well. Garbage in, Louder garbage out

 

[MarkIV]

FQP13N10 do not work properly in a KL203. And the input match will be way off. 2.8. Not to mention the loss off power versus the original part.
A lot of speculation as to what the part is. And some suggestions are ridiculous.

 

[Handy Andy]

IF you are referring to this board...



Then realize the MOSFET biasing used is 10K source to 3.3K ground with the MSFT Gate fed, tapped from it.

For Bias, it's regulated there is a zener diode used Dz1 - bottom left corner to the left of the relay.



Either IRF520 or more than likely a 13N10 are the parts in question.

Note the combiner ~ 2 wind - leaving pretty low inductance - which translates to the use of the output capacitance of the MOSFET's to make up the difference to meet the impedance - which should be 50 ohm.

The smashed cover of the relay is what gets me....

CIAO!

 

[nomadradio]

All IRF520 are not created equal. Minor differences that are within the spec-sheet limits can occur from one manufacturer to the next.

I found that the S-T IRF520 from Mouser never delivered quite the power that the IR-brand factory parts would show. Never drilled down to why.

My only experience with the FQP13N10 is the Fairchild branded part from Mouser. Pretty sure there are other vendors building that part. Wouldn't be surprised to see differences from one brand of that part to the next.

But just how you would predict those differences is beyond me.

73

 

[Handy Andy]

Im finding the IRF 520 or 13N10's (no not those "L"s either) need a LOT LESS inductance - so the L14 stuff is getting really bizarre...

What I usually see...


I'm posting this so people can see how many turns they need L14 to be to return it back to stock...

So if L14 has been tampered with - good luck...