I do apologize for my somewhat abrasive responses. Sometimes I even make an ass of myself and get things wrong. However, in this case all it takes is the ability to read a schematic and following simple amplifier basics, of keeping your bias isolated from RF. If you think TS didn't know they had a bias issue directly related to being cheap with the number of poles on the relay, take a look at everything they made from the 667 down, and compare the bias switching in the sweet 16.
I've seen more 5 transistor TS units with blown 10uh chokes along with output combiners and transistors than I can shake a stick at. The problem is so bad, they knew they could never get away with that design in any 8 transistor amp and finally deiced to do the right thing and separate RF switching from bias switching. They also had to eliminate all of the front panel push buttons and unshielded PC board traces, to get rid of all of the stray RF pickup they created.
Ok Mr Shockwave, apparently, despite the unreal difficulties I have using this forum w/my dumb smartphone, my responses seem to be getting thru regardless so.......
#1) no need to apologize for whatever you feel strongly about.. You say what you feel needs to be said as I do the same. You've been a bit much for me or let's say more than I bargained for today, but I don't see you as having been rude to me or anything like that so I'm a big boy and will either try to deal with it or just duck out. I'm a talker and well known to be as engaging as anyone else and can argue about almost anything, but never unless I believe it's a valid & worthwhile thing to debate or argue.. In this case I no longer even remember why I came here today but I'm pretty sure it had nothing to do with Texas star amps & their design... I don't even remember how it even got on that subject but once you get me started, it's not easy to get me to stop. I have little business debating amp design with you but I feel kind of wrangled into into it somehow. All I know is regardless of how the orig discussion got to Texas star design, when I saw them dismissed as nothing more than a useless piece of junk company, which is how it came off, well I wasn't gonna stand for that and I think I made some good points in defense of them as a company. They are not some Chinese fly by night here today gone tomorrow, could care less company. I felt they had plenty to be praised about aside from award winning amp design, so I did. I see them as an all American success story who has never ripped off anybody & fulfilled a certain need. But I thought I came here tonight or yest, whenever it was, because I rcvd an email from this thread which was originally about the RT1 & evolved into the IRFZ24NPBF. I am not a design engineer nor a full fledged tech, but I have been doing nothing but buy/sell/trade/repair/tune/modify/customize & install, for more than 25 yrs mostly on my own but I have also worked for a couple of major cb shops for maybe 5 or 6 of those years and I got into radio in the mid 70s when everybody had one. I have no formal traininh in electronics but I order to do this, I've made it my business to research everything I can wrap my head around, and spent much time talking to & questioning techs along the way. I have successfully repaired many thousands of radio systems, mostly in the cb realm and related. Prolly more like tens of thousands all told and all self learned plus a certain knack almost like a divining rod, to get pointed to the source of the problem or at least some way to fix it, even via unorthodox means. Ok, so now you know what I'm about... There is very little that I havent fixed or found a way to fix in radios and antenna systems and to a much lesser degree, amps. I have fixed quite a few amps just because lots of failures are obvious and because I've hung around this stuff for so long. I could tell you the basics, the bare basics I suppose, of how an amp works, ie, I'm not clueless, but very limited. Mike Hawkins, the Texas star repair guy for so many years was good enough to teach me alot about how to test and repair them, both on a personal basis and via his videos that he so graciously shared his knowledge with so many ppl. There's alot to be said for that. He'd be the 1ztnone to admit he's no amp engineer but he certainly knows how to fix them and make them do their job and has been at it for about 40 yrs. I even sold a few amps for him to help us both out when t/s laid him off.
Ok, so enough about all that...
This latest spate of emails with me & wwdx began when I took in a job that was pretty big for me. It was an old customer of mine, a trucker who likes big radios and amps for many years. He brought me a newly purchased (by his kids as a birthday present) N3. I know now that the N3 has been out for perhaps over a year, but when he brought it to me, I had not yet even heard of them. I knew about N2 & N4 but not N3 with 4-500 watts... He got it from gi Joe less than 90 days ago as the present. So when he brought it to me, it was maybe less than 2 mos old. It was all blowed up and real good. Fire & brimstone blowed up. Barbeque pit blowed up..
Ironically, years earlier, he brought me a fully blowed up 98vhp which I repaired but in that case it seemed the most prudent thing for me to do was to buy a new amp board and install it which I did and the rebuild turned out well. Also ironically, another mosfet amp. The more I read here the more I get it, thst mosfet amps, esp w/8 fets, are nothing more than an accident waiting to happen. In fact, I never liked mosfets in radios much either ever since they began to surface due the Mitsubishi shakeup. I remember getting into a bit of a hassle with Mr Lewis (Sam) before he died because so many of his early mosfet conversions and factory mosfet radios were failing and I wanted him to take of them via warranty but after the same radio blew up a few times he saod he wasnt going to keep covering and I had a problem w/that because I knew something was wrong about these mosfet radios continually blowing up. At the time, was the controversy going around that his ekl 2030 fets were just rebranded irf520's and many were absolutely convinced that was the case. So. Since he didn't want to warranty some of the radios he already fixed, one day I innocently asked him if I could use the irf520's instead of the erf2030s (because they were much cheaper and I just happened to have a supply of). Well, I hit a major nerve and he went ballistic on me. All I did was ask but I must have been the straw that broke the camels back on that question. Once he calmed down he told me they were not the same and not to use them. Around the same time I had some kl60 rm Italy stinger boards that had blown or missing rm3 (or was it rm1?) fets and I decided to try using the irf520's but they were definitely not the same output pwr but they worked. So anyway, some time later Mr Lewis sent me a letter (I think i still have it from around what, 10 hrs ago or more?) where he basically admitted that there was indeed a problem with those radios and he included a bagful of parts & the instructions how to install in the magnum mosfet radios. After that, his radios held up much better ot seemed. I didn't know what I was doing, but I suspect it had something to do with a more appropriate biasing circuit?
So let me get back to your email about the Texas star design thingy..
I dx ont doubt what you say about the rf & switching pwr supply circuit conflict. All I said is that common sense dictates to me that if they knew about this issue and it was only a matter of 75 cents to correct, sorry but you'll never convince me that they chose 75 cents over a design so much better and so much absolutely necessary, which obviously would bolster their rep and create more confidence & sales, I simply refuse to believe that. I have no doubt in my very inyltuitive mind that there must have been more to to it than that. They are not stupid ppl. It's not very sensible to cut your nose to spite your face in business. And that's why they have been in business for so many decades now, going back to those pre Texas star boxes that started with an O. (temporarily forgot the name) oh yeah, Outcomm.. Whether it was a design mistake or lack of knowledge or whatever, I don't know. All I know is it makes no sense to knowingly have such a catastrophic design flaw as you have characterized it, which could be solve by a mere 75 cents and then to CHOOSE as a business decision, not to. If you believe that's what happened, I would reconsider.
Oh and by the way, I've fixed a fair number of them and only remember 1 or 2 that had burnt chokes and/or combiners. Early on, I believe it ass Mike H who explained to me about the issue with some of the pcbs and the metal standoffs & how they were causing shorts that would burn the chokes and how I had to be on the lookout for that issue. I could never understand why they didn't just use plastic standoffs but it just occurred to me that it's prolly a matter of the metal washers connecting board ground to chassis/heat sink ground to make a better ground plane??? I thought board ground & chassis ground were supposed to be kept seperate to help eliminate rfi?? In any event, only have had to replace 1 or 2 chokes and no splitters/combiners that I recall. Just lucky I guess. This leads back to the 98vhp I got to fix.
So it was the 1st time I saw the RT1's. I started to research and wound up here where I saw this RT1 thread which I don't think was too old of a thread and someone wanted to know about what the hell the remarked RT1's really were. So there were a few comments & opinions in general about how crappy it was to make these mosfet amps esp 8 device. I believe it was NOMAD who gave me some advice but either him nor anyone else seemed to have much insight about the RT1's. Then, a day or 2 later, I 4get who it was posted about what he had determined the RT1's to be. And then there was a followup tomit that seemed to confirm they were IRFZ24NPBF but I didn't pay that much attention to it because by that time I had already contacted my regular wholesale supplier and asked for RT1's. He told me he had some but there was some sort of problem about them and he would have to look into it and get back to me. A day or 2 later he got back to me and said he d he had them so I ordered a set thinking I would be getting a set of RT1's. But when he sent me the digital invoice, they were not as RT1 but as IRFZ24NPBF. I couldn't u derstand that and I was quite concerned, because I had already learned that apparently this radio could do over 400w pep. In fact, the owner of the radio said his meters (dosy & no dummy load) were telling him 550w. I told him to forget about 550 but maybe 250 or 300 was my guess after tune. It says 100w am & 300.ssb on the box. But then I saw the cb shop guy in Florida, oh yeah, Bells, video showing the N3 doing 400 and out of the box and 450 after tune. I was astonished! But then I knew that these RT1s were much higher pwr than the old irf520 version of this amp.
So immediately I contacted my salesman and asked why my order for RT1's was invoiced as IRFZ24NPBFs? He explained that over a year earlier, he had a curomer request some RT1s which they did not yet carry so he contacted their supplier (most likely in China) to get some and the the supplier said they were actually IRFZ24NPBF being buffed and rebranded by Ranger in Malaysia or whatever. My salesman was maybe not aware of that at the time as he doesn't make the orders. So when they came their computer system had them marked as IRFZ24NPBF as far as the stockroom goes. But they were marked as RT1 as far as the general company part #. So that's why there was confusion at 1st when I ordered because my salesman couldn't the stock room could only find IRFZ24NPBF. Then he found out that the supplier had said they were RT1 same thing. Then I remembered the post here in this thread that ID'd them as one and the same IRFZ24NPBF. But I still wasnt fully convinced because now I knew that anyone could take any workable mosfet & buff it out & mark whatever he wanted to on them. Which is why I now think it's a horrible practice to do.
So I tried to do more research on them. I contacted all sorts of industry peeps, even eric Lewis (as he had previously been involved with Ranger) but neither him nor anyone else knew a damn thing about these RT1's or weren't divulging...
I tried looking on Ranger website but they have no mention of N3 there, lol. I tried to email them but they did not answer several emails. Finally I tried calling and I reached someone (Roger) who said he was the only one working in the building due to to covid I guess. He had a very thick chinese? accent and was real hard to understand. He said he worked there for around 35 yrs. I asked him if he could tell me what the RT1's really were or what I could use. He immediately knew what I meant and he had some notes in hand to look it up. I did not tell him anything before hand about the IRFZ24NPBFs I ordered. And he then told me to use IRFZ24NPBF. At that point I was convinced the IRFZ24NPBFs were either the same thing or close enough to use. I had some more questions about the biasing but it became too difficult to u derstand him plus he spoke of a special Chinese measurement tool he used to the biasing and he the. told me to call Chris Holland in calif to get the rest of the procedures. I did so.and I completed the job with Chrics telling me I had done it correctly. But as I mentioned earlier, there is still a problem.
So as far as I recall, I came here today to reiterate to someone that reported 2 different IRFZ24NPBFs that the ones that say IRFZ24NPBF on them are the right thing as far as I know. And then, somehow it evolved into what transpired today! Yikes!
