vk3alk
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« on: July 11, 2020, 02:00:48 AM » |
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Ok this is only meant to be a bit of fun..... This is the PWM that Jon may build ( who knows  ) While Jon builds his stuff .... I will build this ..... It will be larger then what I normally do just so things are easier to see ..... Also the circuit may change as I go along depending on how I feel... Its not a race to finish .... just plod along.... Wayne |
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ka1tdq
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« Reply #1 on: July 11, 2020, 02:16:06 PM » |
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Yes Wayne, but if you run over it with a tank will it still run? Huh? ... Jon |
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N4LTA
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« Reply #2 on: July 11, 2020, 02:24:55 PM » |
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Wayne
Look forward to seeing your new project. I am still a couple of months away from having a shop, but I am collecting stuff for it.
Pat
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vk3alk
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« Reply #3 on: July 12, 2020, 10:28:08 PM » |
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Just a bit of an update....
Have finished building the Inductors for the PWM LPF.....
Wayne
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« Reply #4 on: July 13, 2020, 04:30:17 PM » |
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Wondered what those were. Looks good. What kind of core?
Pat
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vk3alk
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« Reply #7 on: July 13, 2020, 10:29:17 PM » |
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Hi Rod.... I have used them a few times and they work no problems at all... Have attached a photo of one from a Power Supply.. A bit messy to take apart but after a while you learn some tricks in how to do it quickly.... They definitely have to be gapped...if not then I would say would blow apart If you look at the photo you will see a little piece of PCB which goes between the I and E etc:.... The RM cores come gapped or ungapped .... you need gapped ones.... Have made up the PCB for the PWM and are now on the TX so not far away from building.... It is all on the one PCB..... Have decided to make it small and cramped ...... don't know why really ... amazing how small this stuff can get.... Wayne |
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vk3alk
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« Reply #8 on: July 18, 2020, 01:22:29 AM » |
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Well it's coming along slowly....
Pictures show the partly done board and Triangular waveform at 250Khz.....
Its small but so is Pats board....
Wayne
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« Reply #9 on: July 18, 2020, 12:59:36 PM » |
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Keep it coming. i'd like to see a schematic of the whole discrete pwm generator.
Pat
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vk3alk
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« Reply #10 on: July 28, 2020, 08:16:02 AM » |
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Better do an update.....
Have been building.....picture1 shows what I wanted to do ..... both PWM & TX on the one board..
But was not happy with the TX and so cut the board in half and used another little test TX Module built sometime ago....
Now that Jon is building a 200watt TX I rewound the output transformer to lower the loading to 10 ohms ... which was not difficult and the efficiency remained the same in the mid 90s....
Using a Mark to Space ratio of 60:40 now my PWM can develop 130 watts into 10 ohms so no problems modulating a 200 watt TX...
The TX module has been tested and works well .... 200 watts is fine and probably the max safe power would be 250 watts...
I now just have to complete and test the modulator which works up to the driver chip....
Wayne
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ka1tdq
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« Reply #11 on: July 30, 2020, 12:31:17 AM » |
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Damn Wayne, better hope I don't change my mind and go with a 300 watt rig!  Looks pretty darn good! I haven't built anymore but I'm planning the power supply and modulator in my head and ordering parts on eBay. The cat's meow, believe you me. Off topic, but I just ordered a product from down under. I just purchased the Bitscope https://bitscope.com/#overview which is an oscilloscope for the computer. I've decided that I want my California shack to be neat, modern and clean so I don't want clunky oscopes hanging off the desk. I'll be able to monitor my drain waveforms on one of my computer monitors. One monitor for the scope, one for the SDRplay receiver, and another for web browsing to look up the name of the guy you're talking with while he's rambling on about nothing but you've forgotten his name, dammit. I'm totally sure (California talk) that you're going to beat me to the finish line, but standby! ... Jon |
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vk3alk
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« Reply #12 on: July 30, 2020, 05:00:59 AM » |
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Ohhh doesn't matter about coming first ... I'm just chugging along in my favourite room in the house ... my shack... There is not much activity on AM down here which is a shame as I have these Transmitters and no one to talk too.... Mainly just use them to play music around my house But to get serious about things  I have one of Steves PWM generator boards with an output board too ..... do you want it  If so I will just post it to you.... don't worry about postage or anything its yours if you want.... Wayne |
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ka1tdq
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« Reply #13 on: July 30, 2020, 07:03:26 AM » |
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How can I so no to that? I'll take it! It'll greatly reduce the size of the modulator. Thanks, it's greatly appreciated! And in return if you want any Sherman tank parts, I'll post them to you no problem. Just ask, chances are I probably have it.
Jon Rines
12547 Heatherton Ct, Apt 188
San Diego, CA 92128
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N4LTA
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« Reply #14 on: July 30, 2020, 01:15:23 PM » |
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Wayne - Looks good.
Hoping to get back started soon. Still may be mid to late September. Have been buying lots of replacement parts and bins and cataloging.
Hopefully sooner.
Pat
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VK3HN
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« Reply #15 on: July 31, 2020, 03:29:34 AM » |
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Nice work Wayne. Did you choose the IE33 cores for the LPF inductors over the RM10s for power handling? At what power would you think the RM10s would get too lossy or too hot?
-- Paul VK3HN.
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vk3alk
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« Reply #16 on: July 31, 2020, 05:56:19 AM » |
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Ohhh boy .... have been caught out here.... I do have friends down in Ozzz really Pauls a bit of a builder too and has PWM stuff as well.... Just between us Paul ... so I don't have to ring you .... found a Power Transformer that would be good for you as well as me .... Jaycar sell them .... a 240:120 isolation stepdown tranformer so that gives you close to 170 volts that would percolate all our stuff very well... And Jon will post all things very soon.... and Pat times goes bye so quickly you can probably see the finish line with your new Shack.... Wayne |
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vk3alk
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« Reply #17 on: August 01, 2020, 08:55:13 AM » |
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Nearly there....
Only a low powered test but its working....
My Bench Power Supply hasn't enough power to run the TX fully modulated at 200 watts so will have to build a supply to handle....
For a DSO the AM waveform displayed by my Siglent 1202X is very nice.....
In time will do a specan test as well...
Wayne
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vk3alk
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« Reply #18 on: August 02, 2020, 12:57:00 AM » |
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Hi Jon....
Have removed the Modules and also 2 of the cores ........
Tried to leave as much lead length as possible too ...
The Modulator worked without any problems and the TX was a 4 FET Class E using 11N90s....and run it at appox 200 Watts...
Will post them soon.....
Wayne
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ka1tdq
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« Reply #19 on: August 02, 2020, 03:30:20 AM » |
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With the filter cores too!? Wayne, you are too nice.
I'm excited to resume building this transmitter again. In the meantime I've ordered all the parts from DigiKey that I'll need (see boxes). The size and weight reduction for the modulator going with PWM can't be overstated. The whole transmitter assembly (RF deck, modulator and power supplies) will fit nicely into my cabinet.
Now I can put just the plate modulated rig I recently built on top of the cabinet. It'll never get used but looks really nice. It'll give the nice, "Ooh, aah" factor for the shack. I've only had a couple QSO's with that rig and that's all it'll probably ever have. It's entirely possible that eventually I'll be the last man standing with RF vacuum tube knowledge. ARRL might even post an article with a picture of me in my 90's, complete with drool seeping out the side of my mouth.
Jon
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vk3alk
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« Reply #20 on: August 06, 2020, 11:05:57 PM » |
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Been a little disrupted here ..... we are on stage 4 of this Covid 19 thing.....
Onto something more interesting....
Have uploaded a triangular waveform .... probably would look better on an analog CRO but the lines are straight....
Will do a specan test soon and look at the IMDs etc:
Ohhh too Jon have the box for your stuff...
Will package real soon....
Wayne
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vk3alk
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« Reply #21 on: August 08, 2020, 06:39:38 AM » |
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I won't do any Posts on IMD testing....  Ran a single tone ..... one at 3Khz and the other at 6Khz and the IMD product was 35db down....for whatever that means... I don't trust my 2 tone generator so may do the transmitter some injustice .... Rod if your around the IE33 cores have very low singing.... Ran the transmitter at 225Watts carrier 100% modulated with a single tone and could only just hear them.... And Jon will upload a picture of your parcel of goods on your post.... Wayne |
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« Reply #22 on: August 09, 2020, 06:39:59 AM » |
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Sounds good!
Since I have time to sit around and think, quite a dangerous thing, I'm going to do one minor tweak to my plans. I'm still sticking with 200 watts carrier but I'm going to attempt to make this a 40 meter rig. I hate to duplicate capabilities that I already have, and I do have this plate modulated 75 meter rig that I just built. I'm going to buy the Acom 1010 linear to pair with it. The tube is a 4CX800 with cooling from the socket rather than a muffin fan. It'll do well for around 150 watts carrier.
This will give me 40 meter capability and is actually a technical challenge. It's hard to tame the higher frequency and get it stable, but I've got a plan.
Jon
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« Reply #23 on: August 09, 2020, 07:14:49 AM » |
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Ohhh not a plan.... Well thats good ...... Have gone back to another project that I started a while ago now..... I don't want to bore people to death but its a 40M H Bridge that seems to work very well.... Have uploaded a photo.... Goes well ... 52 volts @ 3.8 Amps nearly 200 watts input... The output power is 187 Watts..... Run it for appox 1 hour ( carrier only ) and the FETs were 33C and the Cores 44C ..... Will need to make another one to tidy up the input area and see if my results can be duplicated.... Total cost appox $50- no more.... Will apply some modulation maybe tomorrow or the next day..... Should be fine but its still under test.... Wayne |
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« Reply #24 on: August 09, 2020, 10:36:47 AM » |
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The 4cz800. If you can read Russian, it's really a 4cx600.
Get a couple spare tubes, Jon. Just to be safe. Rotate them every year or so. Again.... Just to be safe
--Shane
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