How Bulletproof is the 13N10 Power MOSFET ??

[unit_399]

I have a lot of CBs sitting around that only need finals to be working 100% again. Trouble is ... they are all rigs that use the 2SC1307, which is NLA. I've tried 2SC1969s and 2SC2312s, but they don't sound as good on-the-air. Especially in an 858SSB chassis, which sounds flat and has no audio "punch" without a 1307 in there.

I've put off converting them to MOSFET finals because I wasn't certain of their reliability long term.

I found this video on Utube. It's a stress test of the FQP13N10 Power MOSFETs in an AT-6666. It was a real eye opener and I figured that some of you guys might be interested, so I'm posting it here.



I wish he had shown the power supply voltage he was running.

Comments ??

- 399

 

[CommandoTech]

I have extensively tested several different types of mosfets in a variety of radios and have found them to be consistently able to not only to withstand the stresses but also exceed the performance of bipolar transistors. You can easily replace those 1307s and get exceptional performance from your rig in doing so.

 

[Handy Andy]

Thanks @unit_399

I hope others are listening to the video - for several variables need to be addressed if you're thinking these are "bulletproof"

When you don't Over-bias - or decide to Re-BIAS the part to your specs
When you don't run a reactive load - with a V(oltage)SWR of Greater than 2
You DON'T Play Music or attempt to run audio over %100 percent modulation...
Do not fiddle with the coils inside to "make it swing more"...

Or give it to a guy in a small closet over at the local Truck Stop for a "Peak and Tune" for ya'.

Then it can be considered Bullet-proof - but just about any radio kept away from "tweaking" is going to accomplish that same thing - at least as far as QC, return and Warranty sakes...

Anything else that can void a seal, warranty or show blatant improper use - they won't make it past the finish line and work in your hands - for long.

The radio was transmitted into no load, no audio - stock - but also remember too, they do have an SWR FOLDBACK shutdown too...

So just open rear end transmit - the thing is smart enough to respond...

IF you run it into a reactive load with a high Voltage component in the SWR - It will sense and attempt to shut down.

Did I mention Voltage? - High volume levels or swing - gives the radio a load and contains a high level RF voltage wave from audio - does not equate to a survivor if fully modulated under a silly test like this into a reactive load.

Only other things that get in the way - are listed above - mostly someone's Fingers...

Then nothing is bulletproof...

 

[secret squirrel]

1.21 Gigawatts of electricity.

 

[nomadradio]

We have seen quirky stability issues with the FQP in radios meant for the IRF520 or (gasp) ERF2030 transistor.

Never have tried to research just what was going on, but when using the right part cures the radio's "mysterious" feedback symptom, I move on the next broken radio.

The FQP is NOT bullet proof. May be marginally tougher than the IRF520, but I'm not sure how you'd measure that in a convincing way. I haven't.

We have had decent results from the HG 2SC1969.

Never forget that a base station's power supply may not have the additional oomph to support a MOSFET mod. The switchmode FETs just are not as efficient as transistors built for RF.

73

 

[Handy Andy]

We have had decent results from the HG 2SC1969.

I second this...

It's not a 2312 - but it lives up to the 1969 fame...so it can (with a little tweak in drive) also swap in with the 2321 to save those older radios with such support.

 

[Holydvr]

I have an RM KL203 that I put 13N10’s into, as it was blown when given to me. I have been using it daily for over a year with zero issues to date.

 

[CommandoTech]

Yes I agree with the above facts that mosfets are primarily for switching applications and are certainly not "bullet proof", in fact they can fail spectacularly (aka grenade). However with the proper installation, care and feeding they can be used in an RF application. I currently have a Cobra 25 mobile that I have modified that runs 24 Volts DC through the modulation transformer to the drain of the final amplifier stage (IRF520N) as an everyday driver on the bench. It has performed flawlessly for over 20 years.

 

[loosecannon]

welcome to the forum commandoTech.

we are a pretty tech heavy bunch here and would love to see what you've done to that cobra 25 as well as other cool stuff you might be experimenting with.

hope you find a lot of good info here as well.
LC

 

[CommandoTech]

Thank you Sir and yes this is the place if you are seeking information on anything RF related. You have a cadre of seasoned professional technicians here and I hope to learn as well as contribute to the best of my ability.

 

[TheRealPorkchop]

There’s no foldback in that radio, nor any other Anytone radio.

In a sense, the radio being modulated or not doesn’t matter. If it were modulated, it might - MIGHT - have went boom or pop.

Heat is heat, regardless of the source but still. Possibly if it had been modulated maybe it would’ve pushed the radio into runaway, so the point is valid but you can’t prove that. Unless you care to replicate his test and then make sure to point everything that was wrong and left out, which really wasn’t much of anything.

The purpose of that video was to prove the 13n10’s weren’t the ticking time bombs that some idiot claimed they were, the Jawa lied.

 

[Handy Andy]

There’s no foldback in that radio, nor any other Anytone radio.

TOT - Time Out Timer - of course it doesn't do anything for SWR issues...

The Fold back - I'm referring to is how the transmitter output power "falls" when it does not see a correctly set up antenna to LOAD into - the dropped energy is the heat lost in the transmitter Final and Driver. The output Network is different from the older designs.

One thing no one else seems to notice is how they designed the output network and where they place the filter elements and the values used. You see this now as a "standard" for others to copy.

You mentioned one time about 1N4148's being used in some radio's as replacements instead of Zeners - this video is a good example as to why the Zeners are needed - reflections do return and have to be dissipated somehow - this radio is protected using several matching network methods to help the transmitter survive in high SWR conditions and the devices used to protect the Gates.

 

[TheRealPorkchop]

What does the TOT have to do with anything? You can turn that off.

For the rest of it, it was modeled and it's nothing more than a low pass filter.

 

[Handy Andy]

Low-Pass filter - yes, idealized - built better than older designs - correct?

As a spoiler - here's the point I was trying to make because it's shown in the video...

Now granted, the SWR icon is lit...
That is what it's for...High SWR
The output network is idealized to "hold back"
or "fold back" power to keep the transmitter from getting damaged.

The burden of proof is on you...
​

 

[TheRealPorkchop]

Right, a foldback circuit would lower the power in an attempt to save the radio. That radio doesn’t have such a circuit, if it does, how about you show us on the schematic.

That SWR protection can be turned off. It’s either transmit or no transmit - not reduced power. If it had the transmitter shut down, there’d be no heat generated.

What I’m saying is proven right in that video and I’m pretty sure if you look at the schematic for that radio you’ll see there is no “foldback” circuit to be found. It’s a cheap China CB glorified as a 10m radio, show me one CB radio with a foldback circuit. True HAM rigs, yes. CB, no.

I think that puts the burden of proof on you, show it by schematic or better yet, video.