I do not think any of us in the radio business is ever going to put your work down, it stands for itself with the results; and does so with fine looking craftsmanship I might add. Great job, would not hesitate to buy any of your projects from you either. You are in fact a class act. I have liked everything I have seen you do as well. WWS030, see ya.
Your the best I'm giving up radio. I did not know motor motor mouth maul made a modulator board. I need a 10-8 mosfet box for the mobile. Amplifiers went to junk I'm a 2 pill to one board man. Your a electronics engineer well I wish if you ever had time you would build my dream box. I'm good as a bench tech not a engineer. I'm throwing money away on junk. Your the man.
Thank you guys for embracing modern RF design and the use of spectrum analyzers and oscilloscopes for modulation. There's quite a bit of knowledge out there and it would be a shame if it was not putting good use. That CB radio kept getting the bad rap of crappy linear amplifiers that spewed harmonica over the band, and splattered constantly.
Good Job Sharky ....The Voltage reminds me of when I was Communicator in the Corps all our Gear in Armor Vehicles was 48V DC ....our Rigs had a real Long Life Cycle on 48V even with the Extreme Heat and Vibration
very great job.. love ur videos.. each n everyone.. and ty for taking the time to explain the findings n outcome of the process is in ur experience of each project!! please keep up the amazing work!! wish we had more people like you in the hobby n in the world in general!! 73s from west virginia!! ✌️😎
Very nice work! .. I'm surprised you haven't made and fitted a basic forward and reverse power sensor on the antenna output (most PA's/Transmitters have them), if you had then you could then automatically attenuate the input power (simple PIN diode attenuator) to provide at least some protection for those precious LDMOS.
hey brother..no words...amazing job..and you know what?you are very very good guy...honestly you are from the few good guys out there who they want to share knowledge and tips.. i enjoy one by one and every one video of of you i didnt post on any of your videos because my english sometimes is not so good to describe what i wanted to say...heheh but i have to soooo wish you the best to you and your family keep it up greetings from greece
Have you looked at w6pql's site? Lots of LDMOS goodies and schematics. I'm using his bias controller board that protects against SWR and such. Only thing I'd recommend is keeping all your input and output coax the same length on each pallet, it's hard to tell but the coax's going to the combiner do not look equal.
Have you done any work on amplifier designs for lower frequencies, like for the 160 van, or they do 500 kilohertz ham band mosfet seemed that they would be a great fit for those. Being low frequency they should give you a full potential
Nice work. I want just 1 pallet kit. To start. Maybe if it goes ok i will try a 2 kit. Question tho. I want to see how they do as a straight 48 volt set up. How much output. I do not want to push it to 2kw . I would be very happy at the 12 to 15 range. We spoke a little awhile back . I wanna do this now.
Yeah LDMoss will only handle high SWR if you have the amperage throttled... I fire and test brand new pallets out at 48volts 15amps on the HP and once they make 500 watts then I will turn the amps up to 35 for 900watts then I figure they're good to go in the transmitter where I tune them up to 1250watts each before combining them. ( We use a Wilkinson combiner ) We had a low pass filter fail at work today and sent 2 of the 6 18XR LDMoss to the moon In one of our 6KW boxes 😞
Sharky did u add electrolytic cap for capasatance... I'm asking because a electrolytic is polerised .. or did u use a ceramic ... I didn't make that clear so just asking ...and what puff ??
The nice thing about LDMoss is lot and even the type of transistor does not matter I have mixed them before and as long as you set your pallets up to do the same power within 75 Watts before you combine them it will be fine :-) I have even mixed Chinese knock off transistors with genuine ones ( probably not the best idea )
From what iv experienced both amplifiers must be totally identical in every way.. a mirror image. One slight imperfection and it will cause a phase difference. 2x 500w pallets never gives you 1kw. Built 188xr PAs on 50, 144 and fm band with great success. But never combined them.
Hi, do you know where to get those output transformers? Also I am trying to see if type 67 core will work on 7mhz. I wasn’t able to find much info on the type 67 material.
Nice peak numbers, but you're getting 1KW from 2.2W and 4KW from 18W. That is wayyy too compressed and non linear at that sort of power, generating tons of IMD or splatter. It will be much cleaner to run it below 2.5KW PEP for sure. Rule of thumb is not to exceed 1dB gain compression for clean output.
Hi, I'd like to build my own amp if I can. And after looking at your setup it looks relatively straightforward. Do you have a list of the parts that you used to build this setup? Are the pallets from a particular place you'd be willing to share? I'm not really sure where to start, and I'm a little bit leery of just ordering some of the kits that are available on eBay without talking to somebody else who has more experience.
I definately need to get myself a two pallet LDMOS kits that you sell, so with that being said, when you get settled down in your new Family home !!!.😏👍 Your build quality is fantastic as far as I'am concerned, very clean and organized. Are those RF coax connectors your using the UHF mini connectors or the Mini "N" connectors?, they dont look like BNC's or PL-259's???
Sharky do you sell the power supplies? I dont have the equipment you do and even If I did I have no chance of making a pallet kit work will you build me one?
Sharky, do you have any one video where one could learn to build at least a single pallet? id love to take it on, my biggest challenge i believe would be the keying and bias circuits.
Bias is nothing to get excited about. It's only important if running ssb mode. Get yourself a decent current limiting bench supply. And everyone watch for BLF188XR without the little Knicks in the drain tabs as they are counterfeit. They produce 100w then there is the flash of death.
Congratulations, but I have some comments that might be useful for your next project. Your non switching regulated power supply is certainly good enough, it is linear regulated but regulation is not very stable because it does drop a few volts under full current. I have a 50 volt p.s. without any kind of regulation but voltage swinging is limited by swamping resistors. May I suggest a couple of hints? Splitter and combiner should have balancing resistors. I ordered two 4 to 1 from Communications Concepts Inc, the splitter at the input is very small but does have balancing resistors, output combiner is rated for 5Kw and has four balancing resistors rated for 500w each. I don't like noise from the blowers. I suggest to place a couple of 50 volt 170mm blowers, which are barely whispering running during standby at only 13 volts. Let them switch to 15 volts during TX periods, jump to 20 volt when heatsink reaches 55° Celsius, and all the way to 50 volts if temperature goes up to 80°, which has never happened yet in my 4Kw PEP amp. Fresh air flow must go straight. In my case it comes from front panel and blowers extract hot air from the rear. First precaution is to never over drive the amp, so driving power monitoring that removes RF if it goes beyond 8 watts is a must. I have 6dB and 10dB power attenuators selectable from the front panel by two coaxial jumpers, so I can drive the amplifier with 5w, 20w, 50w or 200w but RF drive monitoring is a must just in case I make a fatal mistake. SWR protection is a must too, because here we can make mistakes by selecting the wrong coax, the wrong drive frequency or the wrong output filter. Two vacuum output relays redundant working in parallel should be a little better than your regular relays. Current of each module should be measured to be able to switch off the power supply as soon as current goes over 40A, for instance. In my case current for each module is switched by four independent power MOSFET. My amplifier was built three years ago with four ldmos mrfe6vp1k25h rated for 1250w each, in a multiband all mode amplifier configuration. It can deliver up to 5Kw because output combiner and filters are big enough, but I realized that it is not linear enough above 2500w or so, even after setting idling currento to 2.5A for each device, which makes 10A in all or 500w of heat as soon as I PTT. It runs very linear at 1Kw, and still good enough at 2Kw or 500w PEP for each module with worst intermodulation distortions more than 35dB down. It runs very smooth. Blowers are barely audible because the 55°C switch comes on very seldom and the 80°C has never kicked in, but it will if I would transmit non stop all day long. I built a huge bank of low pass filters, six in all from 10 to 160m plus one for 6m that is always in line because is soldered directly to the big 7-16 output connector. I can't be wrong because it's the only connector of this type in the shack. It has two huge heatsinks that weight a ton and case in standard 19 rack at four units hight is not light either. Total weight is 40Kg, excluding external power supply which is unregulated, very much the same as yours but with componentes inside a rack format case. A single toroidal transformer weights 25Kg and fits inside a two units because is very low profile, It has two huges diodes bolted to ground and another two bolted to an insulated heatsink, plus several huge capacitors of course. Unregulated voltage rests at 52 volts because there are big swamping resistors that disipate some heat but avoid voltage to go any higher, and swings down to 48 volts on average under normal operation. A lot of work and money, but ...very happy.
Very well executed. Too bad the mosfet gave his soul to the creator. Have you considered running a VSWR sensor and harnessing ref voltage to command an anpop maybe a 741 for example, to command the excitation off and bias? gets the idea. Sorry my english 73´s
Long story short... I wanted to build my own amp and found some LDMOS pallets for sale. The pallets I bought ended up being terrible so I decided to build my own. BBI's videos helped and motivated me quite a bit to build my own box. A year and a half-ish later, here I am.
If you want to run clean you better stick with the 65V switcher because with the linear supply you are messing with load line issue and compression. Those transistors are made for 65V not 50V.
Those transistors work very well at 50 volts, and efficiency increases a lot at 40 volts! Running at 65 volts gives maximum gain and power, but is too risky.
President Kennedy's children would drop by the Oval Office and he would drop everything to talk to them. He was asked if he worried he might be upsetting officials who had to wait until he was done playing with the children. He said "life is short and they're my number 1 fans". I'm 70 now I had two children die at birth. I envy you.
