An excellent example of how, with high knowledge and the possession of quality measuring and diagnostic equipment, you can achieve excellent results. Thanks for your time and demonstration.

The experts in RF Amplifiers are very rare and you are one of them, you got a new subscriber

@KH07734

Ай бұрын

I spent 4 years learning electronics in grade school. I use basically the same process you use to troubleshoot. My eyes are less than normal lately so Ibtake a bit longer to complete the tasks.

Yikes, I bet those FET's a worth a bundle! Nice that it was just that board. Thumbs up bud!

@TRXLab

8 жыл бұрын

750 each...,Paul. Happy that these survived... Thanks for stopping by. Hey bud what's going on where are the new vids?? Take care 73

@hankbizzo5

7 жыл бұрын

Wow 2 of my favorite KZreadrs.. Thank you for all the great content, keep up the awesome work!!

@mitch3064

5 жыл бұрын

@@hankbizzo5 My thoughts exactly. Call me what you will but to me it is sort of like reading Issac Newton and Albert Einstein writing to each other(yes I know they could not do that). These two along with Dave from EEVBLOG, and ElectroBoom are my favorites, electronic Gurus.

@andrewmullen5770

4 жыл бұрын

Me too! They both provide so much information and inspiration. In my perfect life i would be doing these things for a living!

@JustinRuth-km4wz

3 ай бұрын

Hello Mr Carlson you are amazing man. Listen we deal and work with the 188 ldmos chip ..I'm a big DX guy and build my own amps and modulators... Love your channel and what u do ..ur channle along with this one are by far my fav

Fantastic repair way beyond my level of competence and understanding, but you explain things so well I can get my head around most of it. I bet you could make my old FRG 7 really sing! 73’s Lynton

That was better than watching a movie, It was good to watch and learn, thank you TRX Bench.

Great video once again! I really enjoyed your explanations and walking us through the procedures to test and repair this amplifier. Very well done! 73!

@TRXLab

8 жыл бұрын

Thank you very much Nicholas! 73

Peter, great video. Been playing with high power solid states PA's for years but still learned a lot of the newer techniques. Good job!

@TRXLab

7 жыл бұрын

Thanks for watching Randy! 73

An excellent,methodical and complete repair, Peter. Very enjoyable to watch. Thank you. 73.

@TRXLab

7 жыл бұрын

Thanks for watching 73

You have some nice test equipment. The analyzer to view frequency and the SWR as you switch between the bands gives a cool perspective of health all at once. As always I find watching these videos so interesting, and entertaining, while at the same time trying to learn something more each time I watch one.

@TRXLab

7 жыл бұрын

Glad that you liked it Michelle! Thanks for stepping in 73

So thorough and takes a lot of time to put a careful video together as well. Very useful. I'm only just starting to understand so many concepts with amplifiers and information like this is very helpful. Thank you for doing these. All of this to talk to OMs, makes our hobby seem kind of silly really. :-)

Nice work, Peter. Thanks for sharing the repair with us.

@TRXLab

8 жыл бұрын

Thanks for watching Rober. 73

Great video Peter, like the safety test performed. Keep them comming. Thanks, Greg

@TRXLab

8 жыл бұрын

Hi Greg, thanks for stopping by, Yeah I always perform this safety test after fixing a device with internal 230V power supply. 73

Great video again I really enjoy your videos you are a very good engineer and your commentary is very clear to follow I sit and watch always with interest .Thanks again for posting

@TRXLab

7 жыл бұрын

Thank you John glad that you like it...73

Another interesting video viewed, great job as usual Peter.

Thank you very much, as always, Peter!!! Great video as always!! That is one impressive amplifier!!

@TRXLab

8 жыл бұрын

Thank you Brian! 73

I must have missed the AFP re-adjustment that started the whole problem? Thanks Peter for another great video. I appreciate your attention to detail.

I always appreciated my repair folks, but even more so after following along this diagnosis & repair!

@TRXLab

7 жыл бұрын

Thank you Jim! All the best and 73

This is amazing. Watching this video and how you methodically progress through troubleshooting the amplifier made me appreciate the work that was involved in its design and construction. I wish I knew enough to be able to build one of these. I don't know where to get a primer on filter networks, and I don't even have faith in my ability to build a power supply of my own design. Someone else's, absolutely!

@TRXLab

7 жыл бұрын

Thanks for feed back Ahmed. 73

Another great video! I'm going to have to watch it another 6 times for it all to sink in!

This guy is next level technician...period prolly the best on entertainment

Hello Peter!!!...Very nice work, I really enjoy watching your videos!!!

Hello Peter for making the nice video, with a thorough checkout of the amplier circuits. I designed some high reliability airborne power amplifers in the past and wanted to add a few recommendations. Since this amplier is for amateur use, the standards I recommend will be somewhat less but, still useful for general guidelines.

Extremely thorough test, really learned a lot and enjoyed! Thanks - Lloyd W9NLA

@TRXLab

7 жыл бұрын

Thank you Lloyd 73

Good explanation of troubleshooting. Thanks for sharing your work. Impressive!

@TRXLab

7 жыл бұрын

Thanks for feed-back and watching 73

I always like to keep an eye on you my friend to see what you are up to :) Another great job Peter. Cheers John

@TRXLab

8 жыл бұрын

I'm always glad to see you here my friend! Thanks for watching Cheers

Thank you for this interesting and detailed video. Great troubleshooting.👍

You do great work Sir enjoy viewing your videos and learn a few things too. Thanks for sharing.

The world needs more people like you! Genius

@TRXLab

6 жыл бұрын

Thanks Jim!

The suggestion for the changing of the video speed was spot on. Thank you. It actually helps in other ways. Somewhat often people on KZread talk a little fast for my old brain, so your speech pattern, at 1.25 help smooth things out, and not be too fast for my comprehension. Your English is fantastic. My ability to sprechen Sie Deutsch ist sehr klein. Maybe 30 words left over from learning a bit from my girlfriend while I lived in the city of Bitburg for a few years. Nice addition to learning some of the language was that her father was a distributor for Bitburger Pils. 40 years of not using it hasn't helped.

@TRXLab

5 жыл бұрын

Thanks for the kind feed back Mitch and really glad that you liked the video! Hope you still enjoy Bittburger lol. Ich wünsche einen schönen Sonntag 73

Very impressive work.

That harmonic suppression is beautiful at that output power level!

@TRXLab

7 жыл бұрын

Right it is really not to bad. All the filtering is just working fine 73

Again a very nice instructive video, however I'm a technician but not well-versed in high frequency technic, but your outstanding explanation did me understood everything very well. As I mentioned before with your explanation with the switching power supply, your english is for me as a dutchy, 100% understandable and more clear then a native speaker. Thank you very much!

@TRXLab

8 жыл бұрын

Hi Patrick, thanks for the feed-back glad that you like it. 73

Great diagnosis, it is too easy to rush through a repair, well done for checking the low pass filters. 73

@TRXLab

8 жыл бұрын

Thanks for Feed-back 73

@PhilipEvans11

7 жыл бұрын

g0fvt hi I have an fm 250w- 300+ and it was given to me with a working amp with driver for spares the transistor blf25 are the same but -I wonder if you could advise me why side is rd in and out as there is 2 bnc on the case of The spare I no power around 30-46vdc input2-4w maybe less I want to add a LPF to it with power and drive

@g0fvt

7 жыл бұрын

The collectors of the transistors will usually drive the output transformer, the windings of that will generally follow a short path to the output BNC. Even if you get input and output connections reversed you are unlikely to damage the power stage as long as the drive is not excessive

Absolutely wonderful, entertaining and delightful. Glad to be a subscriber.

@TRXLab

8 жыл бұрын

Thanks for the kind feed-back Mart! 73

thanks trx bench i always learn from your videos keep up the good work

@TRXLab

8 жыл бұрын

Thanks for your Feed-back. 73

3:49 oh WOW! Thank you for great videos!

Great explanations and good job on the troubleshooting.

@TRXLab

2 жыл бұрын

Thanks

Really a Nice video again. Thank you and best regards Peter

Ooo what fun. Looks like maybe an arc over from high SWR caused a thermal runaway. Great video!

"Magic Smoke Escaped" I Subscribed and Hit the Bell the second I heard you say that :) . I personally have seen a 1 inch high flame come from one of those SMT ceramic capacitors; those little caps can do a lot of damage. You are an amazing technician and we are all blessed to watch you in action. God Bless You TRX ! 73 Lawrence VA7LTX

@TRXLab

3 ай бұрын

Thanks for sub!

Excellent and informative. Thank you.

Hi Peter. All of your videos are very informative. This one to me really shows your extreme knowledge. I would love to own this amp. I wonder how many the old guy built. Perfect for a transistor amp. I would really love to own this one. The owner should be thankful for you knowledge and to own such a nicely designed amp. Very nice to see it repaired.

Another great video Peter! Very well explained. I liked your dummy load... I have a EKD-100 for restoring.73's

@TRXLab

8 жыл бұрын

Hey Yvo, nice to see you and thanks for your feed back! Yeah the RFT devices produced in the former GDR are really rough and good for heavy duty. Hope you will do a video on the EKD-100 nice SW receiver. Take care my friend 73

That is one bad to the bone amplifier! Very nice equipment there.

Very concise and very detailed. A terrific video !!!!!!!!!!!!

@TRXLab

8 жыл бұрын

Hi, glad to see you!! Hope you are okay. Thanks for watching and comment 73

I like your DCA55 component tester. It's really useful.

Thanks for these vodeos Peter lots of good info here.

@TRXLab

8 жыл бұрын

Glad that it is useful for you Grant. . Thanks for watching 73

This is spectacular!👍😃

well done Peter that is good testing to check for earth leakage very important were safety is concerned I used to do P.A.T testing Pats stands for Portable Appliance and Testing.

Enjoy your videos and this one was no exception. I read through the Q&As of others and now have no questions. Good job 73 Leo K1ZEK

Well done! Good repair and good video, as usual! Thanks, Peter! I found myself wondering through most of the video what could have done that kind of damage, but then you found the SWR protection circuit was out of adjustment and the small, seldom used part of my brain that stores useful information realized that a high SWR situation could mean that there were some seriously high RF voltages playing around inside that amp.

@TRXLab

8 жыл бұрын

LOL yeah some seriously high RF :-) Thanks for stopping by Adam! Take care 73

@subramanianr7206

2 жыл бұрын

@@oldjarhead386 yes, very appropriate question and he had not shown the same on the video 🙄 De VU2RZA

Wonderful amp quality

After going step by step watching this.... you did everything right. I suspect a roach climbed between that circuit and created a ground fault for a long enough period while the amp was not engaged on. But long enough to create a little mini heating element and the burn occurred. What I don't see in this circuit design is a fuse between the main PSU and this burnt circuit which would have blown at the current a roach would draw. The only flaw in the circuit design was lack of a fuse element after the main PSU to protect the entire system from fire hazard. I will be placing a correct fuse in my own system which is very much the same as this unit but half the output and of course 48 volts. Thank you for posting this video. It was very informative not only for repair study but concept design as well! Good job on the entire video and thank you. If it wasn't a roach then it may have been an arc caused by too much solder on the main (RED) wire that may have melted during or at the end of operation... then while the operator was asleep and the unit still powered... MAGIC SMOKE? He or she wakes up and suddenly the amp will not function.

@TRXLab

2 жыл бұрын

LOL yeah may be...Thanks for feed back

Very thorough testing very impressive Peter, as usual 73's VK6NJP

@TRXLab

7 жыл бұрын

Yeah a lot of work to make sure that the PA is working...Thanks for watching Jim 73

Another great lesson, thanks Peter. 73s de IW0HEX Pasquale

@TRXLab

8 жыл бұрын

Glad that you like it Pasquale. Thanks for stopping by 73

Great video thank you Peter!

@TRXLab

8 жыл бұрын

Thanks for watching Dennis! 73

Very much enjoyed your video thank you regards steve

@TRXLab

7 жыл бұрын

Thanks for watching and feed-back 73

A good power amplifier will have protection circuitry that monitors forward power, reflected power, input power, output power, output device DC current, output device power dissipation, and of course output device junction temperature. In most cases, the protection circuitry should reduce input drive to properly protect the output devices. The protection circuit should never abruptly cutoff power because, this can generate damaging transients. Instead, it should fold back ouput power like a power supply folds back current when the current limit is exceeded. With the amplifier you are working with in the video, the manufacturer may have set the cutout point at a specific reflected voltage on the directional coupler (which relates to a reflected RF power level instead of an actual VSWR ratio). For best reliability, output power should start folding back at VSWR ratios greater than 1.5:1.

thumbs up man, i want one of those 10 kw tube amplifiers for broadcasting ;)

É bonito ver um verdadeiro técnico!!

@TRXLab

7 жыл бұрын

Thank you 73

Those FETs are huge!

@TRXLab

3 жыл бұрын

and cost a bug of money

Danke fuer deine video! Sehr gut! Danke schön.

good job and nice video

@TRXLab

7 жыл бұрын

Thank you

Peter, nice one again.Big thumbs up.Well that kind of pots are really bad, I've lot's of problems with them, since that I always use Bourns pots one critical circuits.The fault on the pot could be related to heat that it get's from the RF board, and with time it's gone deteriorate till complete failure.Again good job.

@TRXLab

8 жыл бұрын

Hi Nuno, thanks for feed-back. Well there are a lot of crappy pots on the market and the Bourns really first class but the used are already precision pots and not that bad. But the permanent heat is a problem to all components..Again thanks for watching 73

SWR protection circuit was out of adjustment, great job and 73! YO5CAT

@TRXLab

8 жыл бұрын

Thanks for fed-back 73

schönes Output Signal.. sehr nice 73

Great video - very instructive. 73 from VK6HIL

@TRXLab

5 жыл бұрын

Thanks for feed back 73

Very detailed analysis of the issues Peter. That was a lot of testing to go through. You really did a good job of explaining that. You thing it may have just been a weak link in the board that caused the failure? Or maybe that tiny capacitor shorted?Thanks for the great video my friend.

@TRXLab

8 жыл бұрын

Hi Buddy thank you. Well really not 100% sure what the cause was as other than the pot for swr all turned out to be good.. May be it was a bad solder point on the burned board but that is not certain. Thanks for watching my friend. 73

Interesting and informative video Peter. 73 de Malcolm M6MYB

@TRXLab

8 жыл бұрын

Thank you Malcolm 73

Great video and some awesome test equipment. I thoroughly enjoyed that very well explained test procedure. I could be wrong but I don't think you reset the Pot to trigger the Thyristor for the AFP LED after turning it fully clockwise.

@TRXLab

Жыл бұрын

Thank you

Excellent video as usual. This channel recommended by Mr. Carlson's Lab.

@TRXLab

8 жыл бұрын

Hi Andrew thanks for watching and feed-back. Paul is a very nice person!! All the best Cheers

Excellent! very nice!

@TRXLab

7 жыл бұрын

Thanks for watching 73

very informative

EXCELLENT !!!

@TRXLab

2 жыл бұрын

Thank you

I didn't see if you adjusted the SWR protection circuit with high power. Did you leave it at the sensitive setting from earlier?

very nice

Great repair. All that power output would make me real nervous though.

@TRXLab

8 жыл бұрын

LOL no fears here.. Thanks for watching 73

very nice 🙂

Thanks for sharing.

@TRXLab

8 жыл бұрын

Thanks for watching! All the best and Cheers

Very nice video Peter. That is quite an interesting amp there. Almost looks homebrew, I guess it was homebrew in more than quantity 1?? Good that you could order a new board. I was thinking you would have to make your own! This kind of amp makes me a little nervous with so much power you can really do damage easily to very expensive parts. Vacuum tube amps are much more tolerant of abuse compared to MOSFETS!

@TRXLab

8 жыл бұрын

Hi Herbert, yes as I said at the beginning it is a semi professional PA and was build a couple of times. It is based on a Motorola application note for the mos fet's..That is the reason why you still get spare parts for it from the USA. Thanks for stopping by 73

Very enjoyable video (still watching it). The SWR detection circuitry is likely between the LPF and the antenna connector. In that location it is unable to protect the FET's in the event of a LPF failure. I have a pair of those FETs for sale should you want a spare. Cheers and 73 - Steve KG4LJB.

@TRXLab

8 жыл бұрын

Hi Steve, thanks for feed-back! All the best and 73

Another great job Peter. ... sweet amp!!!

@TRXLab

6 жыл бұрын

Thank you Jeff 73

Can this transmitter handle being keyed down around the clock?

One hell of a way to keep the shack warm. 73

@TRXLab

8 жыл бұрын

LOL yes that is right.. 73's

Can I know which instrument is used for testing that two Mosfets

I Have watched your video very good what software did you use to measure output power at the end thank you

Very thorough Peter, did you go back and adj. the SWR sensitivity pot with the PA on? Sorry if I missed it, I fell asleep for a few minutes. (Senior moment) K5AZE.... It's nice working on this low voltage stuff, much safer....

Did you readjust the AFP trip point and make sure that the adjustnent pot wasn't intermittent?

What was the 2 spurs at the sides of the carrier when you put power to the amp? 73s pete.

Nice video! I really would like to take a look inside that 1200W RFT dummy load. Thanks, 73.

@TRXLab

8 жыл бұрын

Hi, well there is really nothing exited to find only the full capsuled dummy and rough fans.. Thanks for watching 73

Hi, nice video! Question - where from did you get that new board for such old PA? Where from did you knew what bias current must be?

@TRXLab

8 жыл бұрын

Hi, as I said in the video the PA is based on a application note from Motorola, there you find he suggested Bias. Parts can still purchased here www.communication-concepts.com/ar347/ Hope that helps . Thanks for watching 73

That's quite a burnout on that PCB!

@TRXLab

8 жыл бұрын

Hi Steve, yes with a lot of smoke :-) Happy that the expensive transistors survived.. Thanks for stopping by. Cheers

Great video!! Maybe I missed it but did you check the SWR protection circuit after you repaired the amp?

@TRXLab

8 жыл бұрын

Hi, no you don't missed it, I have done it off camera it is set to approx 2,5:1. Let see how it works. Thanks for watching 73

Very good explanations. Networkanalyzer: would be interesting to know what komponents you need for it.

@TRXLab

8 жыл бұрын

Hi, thank you! You find all about the network-analyser in video #77. 73's

Very nice video. 73. AB2ES/7 in Oregon USA

@TRXLab

5 жыл бұрын

Thank you Bill 73

Peter, Another nice video. Two thumbs up. :-) WB3BJU

@TRXLab

8 жыл бұрын

Thank you Donald! 73's

Mantab

Probably Scenario might have been: SMD multi-layer ceramic condensor dying for micro cracks by heat or maybe even from excessive voltage (maybe by VSWR misalignment?) and then being burned off in a few seconds at that rates could lead to excessive oscillation of your Amplifier. That would then lead to massive over voltages which then are sparking over and burning the massive hole into your PCB. Don't you think?

@tomsmolcnop6358

4 жыл бұрын

Irish Vikin

those mosfets are super tough, good to 50:1 swr at full load.

@TRXLab

8 жыл бұрын

Yeah this MOS-Fets are monsters :-) 73

I think the guy who ran the amp lost his antenna and threw the match out of the final stage of the transmitter's load network to the antenna and it fried the final stage of the transformer PI circuit when it got out of tune when the antenna went up in smoke. So we found that the swr protection section didn't work properly to cut power off to the output section of the power to the finals due to a bad pot trimmer. But what caused the high SWR to begin with the operator most likely. Not selecting the right band for operating of the band of output of the radio.