Splitters/combiners

Discussion in 'Amateur Radio Amplifiers' started by AA7QQ, Jul 3, 2017.

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  1. AF6LJ

    AF6LJ Ham Member QRZ Page

    That is what happens when someone is allowed to hide behind a handle.
    They are not held to the same standard of accountability as we are.
     
  2. AA7QQ

    AA7QQ Ham Member QRZ Page

    I have been watching over time & am pretty close to outing RICHS/REASTON......

    Ed
     
  3. W0AAT

    W0AAT XML Subscriber QRZ Page

    Using a precision flat I lapped some really badly machined chinese LED heatsinks flat. Matter of sitting there and slowly working in as random of a stroke as you can with lapping compound. Heatsinks do not have to be perfect, the heatsink compound can make up a pretty big gap.
     
  4. AC8AC

    AC8AC Ham Member QRZ Page

    interesting thread been thinking about the blf188xr ... kf8od did quite a bit of experimenting with these devices
     
  5. AA7QQ

    AA7QQ Ham Member QRZ Page

    Listen! I am building a junkbox type amplifier.
    I need no microengineering principals. I need no stupid little arguments about microns. I will slap it all together & it shall work just fine, if not, exceed my expectations.
    I have done calculations of the heat sinks, loss of heat from the heat sink through .o1" of thermal transfer epoxy to the .020 wall copper & into the water. I have calculated flow rates with different variables. I will equalize flow rates of each of the 5 tubes & then the 4 pallets.
    I have the radiator out of my 01 Dodge 2500 Cummins powered truck (Only used a couple weeks, till I grenaded my Cummins). I have all of the specs on it & it seems a tad oversized for all 3 amps, should I decide to water cool them & transmit at the same time..
    There will be a 2 gallon tank, 2.1 gallons in the radiator, guessing a gallon in the system. So, almost 5 gallons of coolant & my Cummins had 6 gallons.
    I will also have an auxiliary cooler inside, just in case the outside temp is an issue. There will also be fans as a backup on the heat sinks.
    Temps will all be monitored (LDMOS case & output temp per pallet) through an arduino or R-Pi. Flow rates will also be monitored at the output of each pallet. The SBC will also control the auxiliary cooler fan & the heat sink fans. All info may be outputted to an LCD screen, or possibly one of the several old Android phones I have.
    I am overbuilding the system to take all of the heat from 3 amps at once. 3.9KW of RF out, so, about 3KW of heat removed, as far as I can guesstimate. That is miniscule, compared to the 670HP Cummins that was cooled by the radiator.

    Now, if you have anything to add that might actually help the project, without microengineering, please state it. Otherwise, stop your childish bickering on my thread.

    Ed
     
  6. KD2ACO

    KD2ACO Platinum Subscriber Platinum Subscriber Life Member QRZ Page

    Well Ed, the nice thing about ham radio is that you can mess around and have fun. This isn't medical or aerospace.

    I'm probably not going to make a water cooled transmitter but it's sure interesting watching you go! Thanks for sharing your adventure.
     
  7. AA7QQ

    AA7QQ Ham Member QRZ Page

    Well, I could easily just get a heat sink & drill/tap it, but that is just no fun. For decades, I have thought about a water cooled SS amp. This is the right time to try it with a bunch of junk, that I have a low investment in.
    This will be run mostly from 1000W of free solar panels & 8 AGM batteries (Free from work) providing 50VDC. With my 1.5KW amp, during a sunny Las Vegas day, I can casually talk 6 meters without ever turning on a power supply.
    This will also reduce the electric bill in the summer for AC, & maybe think about the winter & supplementing heat to the radio rooom, but that is after it all works correctly.

    Thank you,
    Ed
     
  8. K7JEM

    K7JEM Ham Member QRZ Page

    I am very sure that your water cooling radiator is way overkill, but better to have too much cooling than not enough!

    As an example, I have a diesel generator that runs 24/7 and produces a near constant 10KW. That generator has a coolant system that holds 2 gallons of water, and its radiator is about the size of one in a smaller car. The engine size is 2L, so not really large.

    Anyway, most of the diesel burned turns into waste heat, less than 30% is actually converted to electricity. Some of the heat is thermally radiated from the engine block into the room where the generator sits. Some of the heat leaves the room through the exhaust system. But most of it leaves through the radiator. I have been told that at least as much heat leaves the radiator as electric power generated, in diesel generators. This seems to be the case, as far as I can tell. So that small cooling system is removing over 10KW of heat on a 24/7 continuous basis. Of course the water temp is near 200 degrees, and you may want something cooler than that, but it gives an idea of what water cooling can do.
     
  9. AA7QQ

    AA7QQ Ham Member QRZ Page

    Yes, I have installed many gensets (Gas & diesel) on boats, along with repowers on them. You need to do the math for heat exchangers. We actually had an American Trader with 2-CAT 3208s that was continuously overheating in Floriduhh. Come to find out, it was repowered in Nova Scotia & the heat exchangers were calculated for 65* water, not 80*+. Moving up to larger exchangers fixed the issue.

    I am overbuilding, due to 100*+ temps here in Vegas.

    Ed
     
  10. K7JEM

    K7JEM Ham Member QRZ Page

    Was 118 in Phoenix yesterday. Only 109 here though.
     

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