How Bulletproof is the 13N10 Power MOSFET ??

[Handy Andy]

You have it already in the network ...

You are the one claiming it doesn't - yet the video shows it survived - so I guess we'll just have to disagree.

IF your thinking "foldback" as a sensor - yes that would require a circuit. However Foldback is also a process a type of feedback. The circuit used is the Network and the Transmitter design itself - so the mis-matched load it's trying to load into - the event itself is the foldback - designed into the transmitter and network. The excessive power mis-match is reflected back into the system and transmitter - it is by it's design to accept and dissipate the power

IN various ways, the "Fold back" can also be demonstrated by the various methods used by earlier CB's to handle mis-match loads by a given rating of time - so in the video we all see the timer - but the radio is still working - just a lot of heat is produced so the effort here is to handle the wasted energy as heat.

So this turns into more of a design criteria than a circuit - but yet using the circuit design to handle the MOSFET - they only allow so much power out - then that which is reflected back is also added summed into the ability of the device to dissipate the unused power - turned into wasted energy and heat.

The clues here are only so much out - to allow nearly as much of it returned back in and let all this power dissipate as heat. It's why I mentioned the issues of "fingers" and left alone - for once it's "set" all the parameters are in place to do such a test as seen in the vid.

I don't have an AT-6666 - only a AT-5555 and that has not needed any work done since I've purchased it.

So do you want to see the AT-5555 or is the AT-6666 a requirement?

 

[TheRealPorkchop]

An LPF network doesn’t contain anything related to limiting or stopping a transmitter nor reducing power. I’ll take a wild stab and say in that radio it’s probably designed to pass anything less than 35mhz. But reduce power or limit power or stop the radio from transmitting…come on, really?

You said it, the radio producing heat. IF it had a foldback circuit, the power would be reduced, that’s what they do and so less heat generated. And IF the swr protection was still enabled, no heat would be produced because the transmitter would be disabled due to no load and an excessively high SWR.

You don’t have a 6666 nor the schematic but you’re telling me it has a foldback circuit in it. Did you miss the part where I said it was modeled? I’d suggest since you don’t have a radio or the schematic that you model it yourself and see just what happens. Or, buy a 6666 and then show us. I’d just like you to point out the foldback circuit that doesn’t exist on the schematic, circuit not sensor.

You can either prove it or you can’t. Paragraphs of rambling thoughts isn’t changing anything, show me that foldback circuit or prove that radio will in fact reduce power output (as a foldback will) and I’ll shut up and send you a case of 6666’s straight off the boat. Not trying to argue with you, really, or be an ass but that radio has no such a thing in it.

 

[Handy Andy]

And...if the radios transmitter power is DERATED downwards so the the reflected power is absorbed and dissipated within the radio...summed together - the radio has ability to work even under no antenna conditions.

I can see where specific places we've dealt with before can use such wording against others saying - "no it doesn't" and in some aspects - both sides are correct.

It is why I issued the state of "keeping fingers out of it" - if it's left to itself - the radio can survive some abuse by handling the conditions it's placed under without damage for a length of time.

Ok, let's play devils advocate and tell it like this...

To some this can be seen as "automatic" to others it's just a duck-radio and too-bad. But to claim it is a feature - almost like a requirement - in order to be even type accepted as a radio to be sold? Well, the FTC might have to get involved and maybe even Ralph Nader has to place his stamp of "DO Not Buy This" approval to get the point across. But people still buy the hype, SMD and Silver soldered circuit traces in that box right along with the notion to pollute the airwaves by their ability to produce noise.

Requirement? No, but ability to emit RF and stay within the emission guidelines set for such a device to be sold as a transmitter IS. In that comparison - then yes, this LPF is needed - else Texas Stars would be on every street corner - monitored by FBI agents or (insert favorite Villain here) attempting to shut down the city by blanketing it with RF from every portion of the spectrum we could make it - emit...

You don't - right now, they can't - so therefore we are safe from the ones that aren't.

I remember times when Galaxy radios - because of their ability to go out of band - many shops could be busted and some did - for selling such equipment. Because it did not meet a - or several - standards set by the FCC.

So now we only have the company - like Anytone producing this radio and such like it, with this SWR protection as a "feature" but yet, when you go back to the older radio designs - that "circuit" or Feature - has been present all this time. The only reason it doesn't seem to work is when others get their fingers into it and change part of the radio to make it perform things that the original sold in the OEM form - could not do. Playing with it or modding it in a way - so in doing THAT very thing (gasp) we shouldn't have, we put ourselves in a position that we caused this "Blowing up" on our own - due to the nature of not paying attention to the details that we needed to when we performed these mods.

 

[TheRealPorkchop]

Tell me you're backpedaling without telling me you're backpedaling.

1) Fingers were put into it to prove a point and I believe that point was proven, very well too.

2) There's never been a cb radio with a foldback in it, never. For the most part the only "swr" circuit in most CB's has been a warning indicator and hasn't ever derated or halted transmitting, until the Qixiang chassis radios (Anytone/Stryker/Etc.).

3) What you're trying to say here, with paragraphs of gibberish, is that the LPF network can adjust itself "on the fly" and that is simply not possible. Fixed parts with fixed values. And if heat is generated, then I guess the entire radio DOES absorb heat, duh. But again, there is absolutely no foldback circuit in any CB, not that AT-6666 or the AT-5555.

4) Can you turn off the SWR protection feature off, yes. Can you adjust it to whatever level you want, yes. Does it have a TOT and can you turn that on or off, yes. Is a TOT a foldback circuit, no. Does a TOT have jack-diddly to do with any of this, no.

5) Let's don't play, let's settle it - model it and/or prove otherwise what you're saying, that there is a foldback circuit in that radio. Show it on the schematic, then show it in operation like how it works in a HAM rig - either, and, or.

6) You, continuing to "circle back" to the same thing reminds me of that little Jawa. You're saying "this is not done right", "it's there", "it's this" and "it's that" but yet you haven't done the one thing needed - show it.

7) You can't.

 

[Handy Andy]

You can either prove it or you can’t. Paragraphs of rambling thoughts isn’t changing anything, show me that foldback circuit or prove that radio will in fact reduce power output (as a foldback will) and I’ll shut up and send you a case of 6666’s straight off the boat. Not trying to argue with you, really, or be an ass but that radio has no such a thing in it.

No, I don't want any more of those things - I've fixed enough of them and to prove or disprove - it's a design, no it's not a separate circuit - it's built into the radios circuits' by it's design. That may be the problem in understanding all of this - is in how to tell you by it's layout, parts selected and used - it is a different design than many are familiar with. Sadly it's also the reason I've moved on from that position. I've fixed enuff of them and my eyes and hands are one thing but my hearts not into trying to tell you something that - unless you fix them and know them - you just can't show anyone anything specific except by their design. Repairing these things you have a much higher respect for their effort in making the radio durable - and if I could go back in time - I'd be doing it using these methods.

If anyone cares, you can see in my postings from when I started here or even at the CB Tricks site - the changes in my approach to radio changed as I gained experiences thru that job. I began to appreciate the nuances radios' became as each production was a redesign of the former. I learned a lot from that and I'm sorry to see that no one else seem to see the changes to the designs like I have. I cannot apologize for something I know and am aware of - I just feel bad that somehow one word has upset so many - but no other word can describe the process as aptly.

The radio is what it is.

 

[TheRealPorkchop]

Yes, it is what it is, a radio without any foldback circuit. You could simply point it out in the schematic but you choose not to because you know good and well it’s just NOT there.

If I’m dumb as a box of rocks and you’re a genius, you can simply show me even if I didn’t understand one single word you said. You absolutely refuse to just simply point it out in a schematic, why? Because you know it’s not there.

"its a layout and design"

Yeah, looks a lot like a chebby low pass filter by layout & design, doesn’t it? Nothing less, nothing more. And it IS a circuit, a series of components designed to derate power but not some mystical, magical self adjusting components as you’re stating. You’re trying to convince the readers that the LPF network is also a foldback circuit and therefore lowers transmitter output power if the load is nonexistent or mismatched. Take the schematic and show where the filter network has anything at all that goes back and DOES limit transmitter output - you can’t because it doesn’t exist.

I said can you show that, can you prove it? The burden of proof IS on you because you’re adamant that it’s there and that it alone is why that radio did not fail in that video.

 

[Handy Andy]

It took Three...

 

[TheRealPorkchop]

It was four but I trimmed it down.

 

[Handy Andy]

but not some mystical, magical self adjusting components as you’re stating.

Hmmm...Show me where I said this?

 

[TheRealPorkchop]

How the LPF “was” or “contained” this foldback that doesn’t exist. Not a verbatim quote.

 

[AudioShockwav]

I like respectful discussion about radios, and how we can debate and still be friends........
Refreshing.

73
Jeff

 

[Allen B]

[QUOTE
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.
[/QUOTE]

None of the 10 meter radios have a "fold back" function. They detect the SWR and shut off and STOP transmitting if the SWR goes above a certain (user set) level. It's all or nothing.

 

[Squints]

As for MOSFETs that are just switches being used in an rf application is they're a MOSFET type that would be considered an upgrade from the fqp13n10 without losing any watts ?

 

[nomadradio]

Well, there's a problem. A switch transistor will always require a finite period of time to make the transition from on to off, and vice versa. If this switching time is short enough, it can amplify RF. The shorter that time, the higher the frequency it can amplify.

The higher the power rating, the longer the switching time. Bigger part just takes longer to turn on and off. The FQP13N10 and IRF520 are about as big as you can get and still get any kind of multiplying factor as a power amplifier. The bigger a switchmode MOSFET gets, the lower the power-gain factor. A transistor that takes five Watts of drive to get ten Watts out isn't worth the bother. There are some linear circuit boards on fleabay using fat higher-power switchmode MOSFETs. Mostly they only claim to work up to about half the frequency of a CB radio.

The IRFZ44 is a MOSFET switch transistor than can do this kind of job, but it's the only other number I know that's workable. Would be nice if somebody did some hands-on research and identified a cheap part that's good for more power. Or longer life when the SWR gets high.

73

 

[brandon7861]

I know its an old thread, but I am also mystified as to how a low pass filter can "fold back" transmitter power. There had to be a reason he was pushing that idea.

Is it possible that the slug in the matching network is chosen to barely handle the forward power, and in the event of a reflection, the increase in current puts the core into saturation and, as a result, the added core losses consume some of the reflected power that would otherwise get back to the finals? When a core saturates, inductance goes down and current goes up, and that should work to lower the voltage on the final, so maybe the core material has something to do with it.

That was my best guess anyhow, unfortunately, the man to ask is MIA.