2x BLF188XR Amp with WATERCOOLING (Part-1)

[@rogeronslow1498]

You cooked those power devices good and proper.

[@Momfasa]

Abolutely beautiful engineering. Well done!

[@langstonlyle6211]

I guess im asking the wrong place but does any of you know of a trick to get back into an instagram account?? I was stupid lost my login password. I would love any tips you can give me!

[@hendrixsergio5474]

@Langston Lyle instablaster ;)

[@langstonlyle6211]

@Hendrix Sergio I really appreciate your reply. I found the site through google and I'm in the hacking process atm. Looks like it's gonna take a while so I will reply here later when my account password hopefully is recovered.

[@langstonlyle6211]

@Hendrix Sergio It worked and I actually got access to my account again. I am so happy! Thank you so much you saved my account!

[@hendrixsergio5474]

@Langston Lyle You are welcome :D

[@АлексейБоярченков]

Why to spread all the heat under all area of the amplifier? If we'd made channels only under the transistors and some near surface?

[@m1geo]

Nicely done! George, M1GEO!

[@ramjet4025]

A classic example of superb RF engineering at its best. Your craftsmanship is is beautiful and exemplary. Do you have an UHF Similar designs? Do you have a contact address?

[@MikePeace]

Where may I purchase the 2 PC Boards for this LDMOS amplifier?

[@nowember711]

I would like to know your opinion on the use of fuel assemblies diodes in the protection of the gates of LDMOS transistors. Which TVS ones do you use?

[@harry4516]

care should be taken that the diode-capacitance is low. Its hard to find powerful diodes with low C. So the TVS are only the first security stage. The second stage are Zener diodes at the gate. The use of diodes at the gate is easier because the gate capacitance of the LDMOS is usually much higher than the C of zener-diodes.

[@nowember711]

@@harry4516 Thank you for your answer. I will use CDSOD323-T05C. Protecting the LDMOS shutters is a priority for me. Another question is the poor performance of the ALC. Power emissions. I follow your work. Thank you very much.

[@rogeronslow1498]

Why did you machine channels in both plates and not just the one with the power devices?

[@harry4516]

good question. My idea was that the solder could flow into the channels. To prevent that I machined both plates with an edge around the channels.

[@rogeronslow1498]

@@harry4516 Ok, why did you solder the two plates together and not just bolt them together with gasket sealer? The lower plate is really just there to seal the channels isn't it? I've recently designed a similar cold plate for another application and I've machined only one plate with a flat plate underneath to seal the cooling fluid. I don't see the advantage of machining both plates.

[@pavelpershin]

Didn't you overcooked it a little based on a copper color changed? VA6AM

[@harry4516]

maybe, its hard the get a specific temperature on the kitchen's oven. But the BLF188 survived the procedure without any problems, so all is fine.

[@va6am_triplexer865]

Thank you. My concern was about transistors. I have no experience with this approach but it looked like a tough test for transistors.

[@mohinderkaur6671]

crispy copper and blf188 . tastes good with butter

[@Henning_Rech]

You can use a cheap "LCD separator" hotplate from China, around 30$, with temperature control. Use BiSn solder and 160°C temperature. It is a very safe process, I soldered several MRF1K50 and a lot of MRFE6S9160 this way, no failure.

[@ohmschool]

Questions (N=2) if I may? *Q1:* The water pump datasheet shows maximum flow rate of 16 Liters/minute, however what is the flow rate you recommend? *Q2:* It appears you are using 100% water, maybe tap or drinking water only. I imagine there is a problem with growth of micro-organisms and algae if the water is not changed and cleaned frequently (e.g. every 3 months or so). How do you handle this problem. Do you simply drain the system of water each time you use it, or do you add some type of chemical to water to kill the bacteria? Growth of micro-organisms + algae is a common problem for closed-loop cooling systems, such as those of CPU cooling, or commercial chilling systems / heat exchangers, so I am curious how you handle it for your amplifier. Thank you and amazing work by the way!!

[@southboundsuarez9832]

I imagine that the copper itself offers antimicrobial qualities similiar to the properties of copper pipe in potable watervsupplies

[@jarekpawlega4859]

How is it performing in the functional circuit now? Is it effective? I'm preparing to make a similar milling, except with additional fins in the channels, for more active surface. (similar to the MIT' instant pop cooler project...). I've had a water cooled copper plate in my PA, made by someone, but it was merely like four turns of 1/4 copper tubing soldered to the plate's surface underneath, and that was not too seriously effective. The PA lasted about 6 months before the thermal protection was no longer allowing me to even send my callsign in full. The transistors were not soldered to the plate either, and the clamps used over them were not too tight, and small. I've taken the whole thing apart and re-doing from the scratch, including the enclosure. I'm very concerned about this sandwich approach and its actual effectiveness. Have you tried some higher than average duty cycles with it? Like i.e. JT65? (like the EME, 6m, 50s/50s). TIA, jarek, va3ncd

[@harry4516]

Hi Jarek, the water cooler allows continous transmission with 1kW until my water gets hot. I have a 10 liters water tank and a aquarium pump. I takes about 25 minutes to heat up tis tank if I do not switch on the fans.

[@princetn]

how is it only outputting 1000watts? each of the transistors is rated up to 1400watts RF output?

[@harry4516]

since the output power does not depend on the transistor. It depends on the winding ratio of the output transformers, and there is a physical limit by the impedances in the whole system compared to the 50 ohms antenna resistance. So, with all these usual designs you will end at about 1000 watts. For higher power you need to combine multiple boards together. Changing the winding ratio is not a good idea, because it will result in much (!) higher current which cannot be handled by the usual PCB designs.

[@princetn]

@@harry4516 It sounds to me like you are not exploiting the transistors to their full potential. You simply settled with a design that running at lower than what the transistors are capable of. For the transformers to handle higher current just use thicker cables. Also I think your filter is killing too much of the output power probably. I don't know why you decided to use transformers for combining the output power? But overall your work and craftsman is really good. I am sure you can make additional improvements to make it output higher power and your main reason for this inefficiency is the broadband design trying to make the amplifier linearly outputing the same power across a large band of frequency. usually RF transmitters/emitters will be only used for one single frequency or a small band. You can't have a design at high power efficient on a large band of frequency.

[@CarNRadio1]

was the wife happy when she saw the video of soldering on the stow?

[@TA4A-32]

Excellent Job 73' TA4AU Im waiting PART-2

[@ghlscitel6714]

Schöne Bastelwerkstatt.

[@ik2nbu]

Fantastic, but high cost for 2 plate copper !

[@harry4516]

Thank you Arnaldo, yes unfortunately the copper plates are expensive. I'm still looking for a cheaper source, but no luck until now.

[@timothyegoroff8333]

You should post a link of where you purchased the blf188xr units, there are so many fakes out there. you may help with preventing the scammers from profiting if you post the link either under the title or in the comments and pin it.

[@harry4516]

Hi, I purchased it from mouser.com. Its a bit more expensive than others, but original quality.

[@defaultuser000]

www.rfparts.com is a great place for genuine parts also. Not sure if they carry this particular LDMOS device, but they have a huge selection of RF power transistors, MOSFETs, and tubes.

[@s55m]

A temperature shock while adding LDMOS on hot plate is big mistake. The results will be visible after long term operation. The "overcooking" should be prevented with gasket sealed water cavity. And if something goes wrong (and it will!), this is irreparable.

[@Henning_Rech]

I agree. I already lost transistors by cooling down too fast. Since I use BiSn solder paste for the transistors and heat up and cool down slowly never a problem. - He could have soldered the copper plates with PbSn in the 1st step, then leak test, and then solder the transistors with BiSn in the 2nd step.

[@dwarslopers]

So hätte ich mir das auch gemacht wenn ich die Werkzeuge hätte. Besser kann man das nicht machen meiner Meinung nach. Es ist einfach die ober coole perfekte Lösung einer Endstufe. Lass Dich nicht von Deiner Frau erwischen! DL6BCH

[@stevenhan1971]

great

[@yb9agaagoengrahardjo342]

i like this de YB9AGA

[@MAC-ez2rq]

Maybe a mixture of engine coolant is better😊

[@СимонБоливар-с7й]

Shaitan machine

[@txxx2826]

Sehr professionell gemacht!