The AM Forum

THE AM BULLETIN BOARD => Class E Forum => Topic started by: ka1tdq on November 24, 2018, 01:45:55 PM



Title: Analog modulating a 1000 watt carrier class E rig
Post by: ka1tdq on November 24, 2018, 01:45:55 PM
I'm interested again in building a 24 FET class E rig for 75 meters. The schematic is already out there, but I've been planning the mechanics of the build. Attached is what I'm going to do. We've discussed this before, but rather than elongate the transformer, I'm going to wrap it on itself as shown in the picture.

Even though it is relatively cheap to build, it will still take money, but I do have a plan. I know it is cheaper to modulate this via PWM, but I still prefer analog Heising modulation. I've done the numbers and here are the components that would be required:

10mH at 25 amps, minimum

2600uF at 450vdc, minimum

The numbers work, and I do have a spare megawatt, single-channel car audio amp.

Is this practical?

Jon


Title: Re: Analog modulating a 1000 watt carrier class E rig
Post by: WBear2GCR on November 24, 2018, 10:13:19 PM
Rather think this post belongs in the Class E section.
Steve WA1QIX has modulated these rigs by assorted means.
Including a class AB amplification section.

My reaction to the car amp idea is definitely maybe.
The first thing you will need is a pretty serious DC supply, as the amp is
going to be a lot less efficient than 100%. If it is a class D car amp, I'd be
cautious... they probably don't like "weird" reactance/phase angles. But,
maybe.

So napkin design says for 1000 watts at 10 volts supply = 100amps!
A bit less at 13.8vdc. But you need more taking into account the efficiency
of the car amp...

Now if you had a Crown Macrotech 2400 run in mono... :D

Don't forget that your modulator's voltage will need to swing whatever the peak
of the RF section puts out, or more (for over 100% positive).

Steve sells the PWM modulator board for pretty low $$, with parts, fyi.

                          _-_-bear


Title: Re: Analog modulating a 1000 watt carrier class E rig
Post by: ka1tdq on November 24, 2018, 10:46:46 PM
I do have a class D car amp. Iíll have some resistance in parallel anyway to damper weird reactance, but efficiency will be depleted further. My solution to a beefy 12 volt supply: a car battery.

When the time comes, I might just go PWM. Why push a Prius with a 450 cubic inch 4 barrel carb. Iím not a car guy, but I think that made sense.

Jon

**But in this case, this is a pretty mother, badass Prius.


Title: Re: Analog modulating a 1000 watt carrier class E rig
Post by: Opcom on November 25, 2018, 12:09:02 AM
I can only add one comment at this point: Copper heat spreader plate


Title: Re: Analog modulating a 1000 watt carrier class E rig
Post by: ka1tdq on November 25, 2018, 03:04:54 AM
Yeah, throw that in the box too!  ;D

Jon


Title: Re: Analog modulating a 1000 watt carrier class E rig
Post by: ka1tdq on November 25, 2018, 07:46:06 AM
...actually, thereís an industrial metal store not too far from my house. I can get very large blocks of aluminum fairly cheap. The block by itsel is a good enough heat sink, but I may put fins on it. 1000 watts at 90% efficiency is still a lot of power to dissipate. Fortunately the antenna dissipates most.

Jon


Title: Re: Analog modulating a 1000 watt carrier class E rig
Post by: WBear2GCR on November 25, 2018, 10:03:01 AM
Imho, you are not going to get much on-air time with a car battery.
Also, if you draw at those currents, you're going to create a boatload of hydrogen gas...
VERY DANGEROUS in the house!

Also at this point it is no longer necessary, afaik, to use 24 fets... newer cost effective devices.

Aluminum heatsinking is likely sufficient.
For heatsinking MASS will work up to the point where it becomes "saturated", then it becomes
an inefficient radiator of heat. Fins are required, or a fan, or a fan + fins (depending on the
actual situation). Getting rid of 100watts of HEAT requires a significant amount of heatsink.
I do this all the time in audio.

Basically you want a big heatsink with 2.5" or better fins, wider spaced is better for natural
convection... big being maybe 8 x 10" or better.

Getting rid of 200 watts of heat, depending on how ur running the proposed transmitter, requires
that much more heatsink. Wakefield's site has the formulas, they're not terribly complex. You only
need an order of magnitude and then add 20% for safety.

In the case of 24 fets, you don't need a copper spreader, since it's already spread!
If you use 8 fets at the same power, MAYBE you need a spreader, since the devices are
small... the thickness of the heatsink's backplate matters...

The transfer between surfaces in heatsinks matters...

Afaik the efficiency of the Class E transmitter is WAY better than 90%, so the transmitters
I've seen generally have relatively modest heatsinking...

As I said this belongs in the Class E section...

                 _-_-


Title: Re: Analog modulating a 1000 watt carrier class E rig
Post by: N1BCG on November 25, 2018, 10:10:42 AM
Whatever the manufacturer claims your car amplifier is rated for is using absolute best case marketing dept-driven DC input watts, so doing the efficiency math drops your options dramatically. And then there's the unflattering THD at high output.

Why 1kW RF?

btw: Heising means common supply and no transformer, just a choke. Not sure if you meant that or a mod transformer with a reactor.


Title: Re: Analog modulating a 1000 watt carrier class E rig
Post by: ka1tdq on November 25, 2018, 10:19:29 AM
Fair enough on the amp and the battery. When the time comes, I'll probably go with PWM. I do need to build a working RF deck though. I'm fairly confident in my ability to do that, but the proof is the wattmeter.

True, 1kw isn't needed. I could simply run it at 500 watts and be happy with that. Then Heising becomes a little more practical. I could probably crank some more out of my current modulator and use that.

I'll continue this thread in the class E section when the time comes. I need to finish my receiver project and then focus on getting the parts for this RF deck.

So, to be continued after tax return time!

Jon


Title: Re: Analog modulating a 1000 watt carrier class E rig
Post by: steve_qix on November 25, 2018, 04:47:39 PM
Ah, go for the full boat  8)   If you have an antenna up high enough above the ground, we should be able to hear you out here in good old New England.  That would be cool.


Title: Re: Analog modulating a 1000 watt carrier class E rig
Post by: steve_qix on November 25, 2018, 04:49:48 PM
Another good reason to go with PWM is you get things like fast overload shutdown for "free".  It's in the design.

Not to mention the smaller size, smaller weight and reasonable power/current requirements.


Title: Re: Analog modulating a 1000 watt carrier class E rig
Post by: Opcom on November 25, 2018, 05:11:38 PM
An AGM battery is supposed to be safe to use regard outgassing, unless it is abused but that is any battery. Don't take my word for it though. I ran one in my truck behind an 8-transistor RF amplifier for a few years and never an issue.


Title: Re: Analog modulating a 1000 watt carrier class E rig
Post by: pa0ast on November 25, 2018, 05:13:30 PM
Have You considered that most car amps are class D Amps. ? The switching freq is still present in the output if not strong suppessed. Could be a problem if you use it as an modulator. Also the switching  power converters that  convert 12 V dc to + and - 48 Vdc that the amplifiers run with , can give problems in the transmitter. You have to filter it well .


Title: Re: Analog modulating a 1000 watt carrier class E rig
Post by: ka1tdq on November 26, 2018, 12:05:18 AM
Yes, weíve spoken on the air with my measly 400 watts carrier before. Iíve also chatted with Tim.

PWM is really the only practical choice at this power level. Iíll save my Crunch car audio amp for blasting Roy Orbison driving down the I-10 in Phoenix.

Jon


Title: Re: Analog modulating a 1000 watt carrier class E rig
Post by: WBear2GCR on November 26, 2018, 01:01:12 AM
Practical is in the eye of the beholder...
QIX did go from AB to Class H to PWM. So, they're all doable! :D

Don't wimp out, go for the full bore!


Title: Re: Analog modulating a 1000 watt carrier class E rig
Post by: steve_qix on November 26, 2018, 05:50:30 PM
Practical is in the eye of the beholder...
QIX did go from AB to Class H to PWM. So, they're all doable! :D

Don't wimp out, go for the full bore!

Never actually used AB - it was class A (below 100 watts).  Then class H (100 to 400 watts), then PWM.  However, now I use PWM for everything above 150 watts.  It's just so much smaller and very reliable.


Title: Re: Analog modulating a 1000 watt carrier class E rig
Post by: ka1tdq on November 26, 2018, 08:05:25 PM
I'm actually just going to just key drain voltage to this thing and make it a CW transmitter. Just pass drain voltage supply through a J-38 key.  Make sure though to put a .01 capacitor across the terminals. 

https://www.youtube.com/watch?v=3gQANgjMEog (https://www.youtube.com/watch?v=3gQANgjMEog)

Kidding...

Jon


Title: Re: Analog modulating a 1000 watt carrier class E rig
Post by: ka1tdq on November 28, 2018, 06:00:18 PM
Behold! The plate of power!

Iíll join an aluminum heat sink on the back with a heat transfer compound.

Jon


Title: Re: Analog modulating a 1000 watt carrier class E rig
Post by: ka1tdq on November 30, 2018, 10:24:29 AM
Not a bad looking coil for being made in a Loweís parking lot (not while driving).

Jon


Title: Re: Analog modulating a 1000 watt carrier class E rig
Post by: PA0NVD on November 30, 2018, 11:24:37 AM
Inside size of a beer can?


Title: Re: Analog modulating a 1000 watt carrier class E rig
Post by: ka1tdq on November 30, 2018, 02:51:44 PM
I wish. An adult toy would be an even better story. Nope, black PVC.


Title: Re: Analog modulating a 1000 watt carrier class E rig
Post by: ka1tdq on December 04, 2018, 08:43:59 PM
Cutting copper strips with tin snips leaves jagged edges and a rough look. Cutting with a paper cutter gives a cleaner look.

Jon


Title: Re: Analog modulating a 1000 watt carrier class E rig
Post by: ka1tdq on April 04, 2019, 10:33:05 PM
I've started this project up again. I've decided to build the 24-FET deck but just run it at 400 watts carrier and use my existing modulator.

I just got the frame today to mount the components on. It's a piece of 1/8" aluminum sheet that's 16" x 30". It'll look similar in design to my 8-FET transmitter, being open frame and all. The good thing is that I've learned a bunch of stuff since that rig that I'll incorporate into this one.

Jon


Title: Re: Analog modulating a 1000 watt carrier class E rig
Post by: ka1tdq on April 06, 2019, 10:23:25 AM
I'm learning to use the markup feature on my iPhone.

I did find a nice block of cherry wood to mount the output transformer to rather than using just teflon.

Jon


Title: Re: Analog modulating a 1000 watt carrier class E rig
Post by: ka1tdq on April 15, 2019, 09:37:29 PM
I have the heat sink mounted to the back of the aluminum block and all the holes drilled and tapped. I'm using a driver for each FET so the next stage is a little pricey. I'm going to build the heat sink assembly with all components then start building the chassis.

A little solid state heavy metal.

Jon


Title: Re: Analog modulating a 1000 watt carrier class E rig
Post by: ka1tdq on May 04, 2019, 11:47:19 AM
It's starting to come together. I've started buying all the silicon stuff. I've made a link for the progress of the project here:

http://ka1tdq.radio/current-project/ (http://ka1tdq.radio/current-project/)

Jon


Title: Re: Analog modulating a 1000 watt carrier class E rig
Post by: ka1tdq on June 16, 2019, 08:30:44 AM
I bought all the parts for the heat sink assembly and now it's starting to take shape.

Jon


Title: Re: Analog modulating a 1000 watt carrier class E rig
Post by: ka1tdq on June 16, 2019, 02:59:53 PM
Here's with all the FETs and drivers mounted. The heat sink assembly is almost done!

Jon


Title: Re: Analog modulating a 1000 watt carrier class E rig
Post by: Opcom on June 16, 2019, 06:08:12 PM
In a wholesale catalog of car audio gear there were the 4KW amps and all of that along with the 100W/CH types. The big stuff was class D.

The point is that the power ratings for hypothetical identically-rated amps were sometimes given as "4000 Watts MAX" with no other indication, and otherwise given as "2000 WATTS RMS". To add to confusion, some would headline with 4000 WATTS, and then in the bullet points, state 2000 WATTS RMS.

Store/shop sales people a lot of times have no idea what this is about and just try to state the higher rating. The salesperson at the distributor will know the facts and was more than happy to explain that MAX meant driven as hard as possible to square wave clipping, which was for the competition and rap/bass-boom car people, and RMS meant without clipping, which would be the rating for the hi-fi people.

Part of a wholesale catalog page attached to clarify the marketing.


Title: Re: Analog modulating a 1000 watt carrier class E rig
Post by: KB2WIG on June 16, 2019, 08:53:29 PM

P,


Nothing about Bird watts, is there?


klc


Title: Re: Analog modulating a 1000 watt carrier class E rig
Post by: ka1tdq on June 17, 2019, 11:20:23 PM
The medieval version of explaining MOSFET amplifiers to the general public.

https://www.youtube.com/watch?v=_rMsgmaBV8g (https://www.youtube.com/watch?v=_rMsgmaBV8g)

Jon


Title: Re: Analog modulating a 1000 watt carrier class E rig
Post by: Opcom on June 18, 2019, 02:37:41 AM

P,


Nothing about Bird watts, is there?


klc

naw.. just the audio frequency kind. Hey the Bird Watts come from the fantastic class E stage!


Title: Re: Analog modulating a 1000 watt carrier class E rig
Post by: ka1tdq on June 21, 2019, 01:52:53 PM
I have the driver rail supply installed and now need to do the tiny soldering of all those small resistors and caps.

Jon


Title: Re: Analog modulating a 1000 watt carrier class E rig
Post by: ka1tdq on June 21, 2019, 08:25:16 PM
...and more stuff

Jon


Title: Re: Analog modulating a 1000 watt carrier class E rig
Post by: steve_qix on June 21, 2019, 08:47:38 PM
Looks good.  The shunt capacitors should be around 1500pF for 6 MOSFETs, unless you're going to run lower power.  It looks as if the shunt is 1000pF.


Title: Re: Analog modulating a 1000 watt carrier class E rig
Post by: ka1tdq on June 21, 2019, 08:59:58 PM
They are 1000pf. Itís what I could find for ATC capacitors. Iím only going to run 400 watts carrier, so everything should be well within margin.

Soldering tolerances are closer than what I expected on paper. Things are really tight! But, Iím going to check everything as I go. This is too big of a transmitter to do otherwise.

Jon


Title: Re: Analog modulating a 1000 watt carrier class E rig
Post by: ka1tdq on June 23, 2019, 09:59:18 AM
The heat sink assembly is all done except for testing the gates under drive and installing the ground shield between the drain and drive buses.

Jon


Title: Re: Analog modulating a 1000 watt carrier class E rig
Post by: steve_qix on June 24, 2019, 03:32:25 AM
The shunt capacitor keeps the drain voltage in check.  It's a good idea to do that - vastly improves reliability (among other things).

I have used these caps (and other similar caps of varying values) with good success in many class E projects:  https://www.ebay.com/itm/560-pF-500-V-5-LOT-OF-1-RUSSIAN-SILVER-MICA-CAPACITOR-SGM-3-3/282488834530?hash=item41c5a589e2:g:lmcAAOSwao1bEkqV (https://www.ebay.com/itm/560-pF-500-V-5-LOT-OF-1-RUSSIAN-SILVER-MICA-CAPACITOR-SGM-3-3/282488834530?hash=item41c5a589e2:g:lmcAAOSwao1bEkqV)

You could put one on each drain bus, which, in addition to the capacitance you already have, would give you a total of slightly over 1500pF.



Title: Re: Analog modulating a 1000 watt carrier class E rig
Post by: ka1tdq on June 24, 2019, 09:05:13 AM
Thanks! Yeah, I thought about that afterward. Even though I plan to only run 400 watts carrier right now (QRP), later on I might try more and couldn't with that limitation in there. It's better just to do everything right from the beginning.

Jon


Title: Re: Analog modulating a 1000 watt carrier class E rig
Post by: Opcom on June 24, 2019, 09:18:41 AM
Just noticed something in the latest image. The RF cables are held in place with large eye bolts. Very appropriate engineering measure for this project.

Used to do something similar with an old rat rod - chained the stoked 400 Pontiac engine to the frame because otherwise it would sometimes break the motor mount on launch. The Millenium Rat is missed.


Title: Re: Analog modulating a 1000 watt carrier class E rig
Post by: K8DI on June 24, 2019, 09:28:58 AM
Maybe it's the picture angle, but it looks like the number of little capacitors is inconsistent -- 4, 5, 5, and 6 per bank. Is this so? Or just my eyes fooling me? If so, why?

Ed


Title: Re: Analog modulating a 1000 watt carrier class E rig
Post by: ka1tdq on June 24, 2019, 10:09:44 AM
Good catch. Those caps are on the DC supply rail for the IXDD bus. I ordered 20 caps with the intention of using 5 per MOSFET rail. During construction I got solder happy and put one too many on one section. I shorted another section.

Itís no biggie. The whole thing is DC common anyway. It shouldnít matter. I know this from my last transmitter. I accidentally wired half of them backwards when during construction I didnít realize they were polarity sensitive. Those that were wired backwards popped like firecrackers. The transmitter still worked fine on half a load.

Jon


Title: Re: Analog modulating a 1000 watt carrier class E rig
Post by: ka1tdq on June 24, 2019, 10:52:42 PM
These are little more expensive, but I think well worth the cost.

https://www.ebay.com/itm/ATC-PORCELAIN-HIGH-POWER-RF-CAPACITOR-680PF-2500VDC-20-MICROSTRIP-TERMINATION/323824215343?hash=item4b656d652f:g:SnAAAOSwyTtc9GVB (https://www.ebay.com/itm/ATC-PORCELAIN-HIGH-POWER-RF-CAPACITOR-680PF-2500VDC-20-MICROSTRIP-TERMINATION/323824215343?hash=item4b656d652f:g:SnAAAOSwyTtc9GVB)

The Russian silver mica caps only have a voltage rating of a little over 500 volts. A combined shunt capacitor value of 1680pf is a little high, but I can stand a little loss in efficiency for an improved safety margin.

On a side note, I'm building this project on a budget of $90/month. It was a challenge put to me by my wife. I cheated a little and sold the ARC-5, but basically it has come this far on a pittance.  All I have left to purchase are the cores, tuning and shunt caps.

Jon


Title: Re: Analog modulating a 1000 watt carrier class E rig
Post by: steve_qix on June 26, 2019, 11:22:10 PM
Those ATC caps will work, and the 500V Russian caps will also work.

The 500V rating is plenty - the highest peak RF voltage at full modulation, assuming the modulator can provide 130V peak is under 500V - and that 500V rating on the cap is the DC rating, so you're good.  The ATC caps I use are typically 500VDC units.  I also use the Russian 500V silver micas.

I tend to go with lower voltage ratings if possible.  For the same (physical) size cap, the current rating will generally be higher with a lower voltage device.




Title: Re: Analog modulating a 1000 watt carrier class E rig
Post by: ka1tdq on June 27, 2019, 05:36:01 AM
I actually decided to go with 8 more of the 1000pf value ATC caps. I'll put two in series and parallel them with the existing ones for exactly 1500pf.  It'll work out mechanically as well since I'll bridge the bottom of the second one with another capacitor rather than using a piece of wire to form a "U".  It'll look like it was meant to be there.

I didn't think about size and current/voltage rating stuff. I'll have a parallel path siphoning off some current and all that good stuff. 


Title: Re: Analog modulating a 1000 watt carrier class E rig
Post by: ka1tdq on June 28, 2019, 04:58:23 PM
It's starting to look like something!

Jon


Title: Re: Analog modulating a 1000 watt carrier class E rig
Post by: ka1tdq on June 29, 2019, 05:03:46 PM
A little more progress.

Jon


Title: Re: Analog modulating a 1000 watt carrier class E rig
Post by: ka1tdq on July 04, 2019, 01:14:56 AM
I can't do any more until the vacuum variable and the cores come in at the end of the month. I did get the additional 1000pf ATC caps, but I won't solder those on until I get ready to test the heat sink assembly.

Jon


Title: Re: Analog modulating a 1000 watt carrier class E rig
Post by: ka1tdq on July 06, 2019, 03:05:27 PM
This picture shows the mounts for the vacuum variable cap almost done. I'll drill a hole for a #10 bolt through the copper to secure the cap mechanically to the plexiglass and it'll serve as a connection point for lugs.

For feng shui, I ordered a clear acrylic 1/4" shaft for the knob. It's also nice to not get zapped while tuning.

Jon


Title: Re: Analog modulating a 1000 watt carrier class E rig
Post by: ka1tdq on August 04, 2019, 02:11:44 AM
I got the meters wired in. All that's left is to complete the heat sink assembly and connect it to the transformer.  

Jon


Title: Re: Analog modulating a 1000 watt carrier class E rig
Post by: steve_qix on August 05, 2019, 08:19:39 AM
Wow !

Well, bring it up slowly; monitor the drains for parasitics on modulation peaks and let us know  :D


Title: Re: Analog modulating a 1000 watt carrier class E rig
Post by: ka1tdq on August 05, 2019, 05:12:47 PM
Slowly is key with these things. It's like a moon shot. Everything has to go right for it to work.

I was finishing up the heat sink assembly and testing drive to all the gates when I discovered that gate drive would come and go. It turns out that the coax cables connecting my VFO to the heat sink assembly were intermittent.  That would've been bad under load!  I tried a different cable and everything was fine.

Jon


Title: Re: Analog modulating a 1000 watt carrier class E rig
Post by: ka1tdq on August 10, 2019, 10:30:52 AM
Things are looking better now. The 90 degree SMA elbows were giving intermittent connection as well. I had just finger tightened them, but I don't want that weak spot in there so I got rid of them.

And I got new cables from HRO (they're in town).

Jon


Title: Re: Analog modulating a 1000 watt carrier class E rig
Post by: steve_qix on August 10, 2019, 10:52:08 PM
The gate waveforms look pretty good.

Do you have duty cycle control?  The on time is a little long for standard MOSFETs, and there may be a slight amount of on-time overlap in the waveforms.  If you superimpose the two traces, one over the other, with the same zero-point, that will reveal any overlap.

It's definitely coming along !!


Title: Re: Analog modulating a 1000 watt carrier class E rig
Post by: ka1tdq on August 11, 2019, 08:55:57 AM
I've remounted the heat sink assembly and just need to do the wiring between it and the rest of the transmitter.

Duty cycle is adjusted by changing the amplitude of the sine wave going to the master IXDD, which drives the slave IXDD's.  I'll kick it back a few notches and shoot for about 43% duty cycle. 

Jon


Title: Re: Analog modulating a 1000 watt carrier class E rig
Post by: ka1tdq on August 11, 2019, 03:02:43 PM
Here's gate drive for each phase with the heat sink assembly mounted. I'm drawing about 8.3 amps at 12 vdc for total IXDD current (not under load; no drain current yet).

Jon


Title: Re: Analog modulating a 1000 watt carrier class E rig
Post by: ka1tdq on August 11, 2019, 06:33:05 PM
It's all done!

I'll apply drain voltage next weekend when I have time.

Jon


Title: Re: Analog modulating a 1000 watt carrier class E rig
Post by: ka1tdq on August 11, 2019, 11:00:34 PM
Before I go too far, this is what I've got on my initial try:

112 watts output for 11.3vdc on the drains at about 15.2 amps total drain current. Efficiency at this point is about 65% and the picture shows the drain waveforms for two of the drains (I'm using the top and bottom drain bus on the scope.

I have the drain power supply on a variac and can bring everything up slowly.

What are your suggestions?

Jon


Title: Re: Analog modulating a 1000 watt carrier class E rig
Post by: steve_qix on August 12, 2019, 07:18:07 PM
I have found that a drain voltage under about 20VDC does not yield good results.

At 20V things usually start to come together.  Also, the design impedance of the RF amplifier should be more or less used.  So if designed for 45V @ 26A (as an example), the impedance of 1.7 ohms should be reasonably maintained (within 30%) for best results.

For 20V, the total current would be around 11A.


Title: Re: Analog modulating a 1000 watt carrier class E rig
Post by: ka1tdq on August 12, 2019, 08:41:18 PM
I haven't found the sweet spot yet, but I'm getting closer!

Here's the waveforms at 300 watts.  I'm running 28.6 Vdrain at around 13.6 amps. That puts me at 78% efficiency.  The current measurement isn't exact since I'm just measuring one drain current and multiplying it by 4.

The dummy load gets warm rather quickly too.

I had to lower the value of one of the fixed doorknob capacitors in the loading circuit because I was getting fully unmeshed.

Jon


Title: Re: Analog modulating a 1000 watt carrier class E rig
Post by: ka1tdq on August 13, 2019, 03:30:29 AM
Here's 400 watts on the dipole and 89% efficiency.

I keep having to back power down as drain voltage isn't up all the way yet. I'm at 35.4 Vdc at around 12.6 amps.

The next step is to remove the variac.  I'll back drain current down for that and then readjust.

My goal was for 400 watts carrier.  I'm there... I just need to ease off this friggin' Ferrari!

Jon


Title: Re: Analog modulating a 1000 watt carrier class E rig
Post by: vk3alk on August 13, 2019, 04:57:19 AM
Well done Jon.... ;D

Should I mention the word PWM next........ :-X

I have one of Steves Overload shutdown kits .... you can have if you want .....
No payment ... can just post to you  :)
Maybe some incentive for the next build....


Wayne


Title: Re: Analog modulating a 1000 watt carrier class E rig
Post by: ka1tdq on August 13, 2019, 07:52:23 AM
Hey Wayne!

I do have PWM on the back of my mind. I came across this helium compressor enclosure some time ago that would fit everything nicely beneath the desk. If and when I decide to go that route, I'll just order the whole enchilada from Steve. I appreciate the offer, but I don't want to waste it either. Time will tell.

In the meantime...

https://www.youtube.com/watch?v=RvV3nn_de2k (https://www.youtube.com/watch?v=RvV3nn_de2k)

Jon


Title: Re: Analog modulating a 1000 watt carrier class E rig
Post by: steve_qix on August 14, 2019, 06:44:54 PM
Wow, you don't need anything NEARLY as big as that box !

Here is a PWM modulator I built which will handle a 24 FET rig no problem.

(http://www.classeradio.com/rsi_modulator_front.jpg)

(http://www.classeradio.com/ris_modulator_inside.jpg)

The power transformer is external, and sits behind the transmitter.  I am NOT a fan of mounting anything heavy on a chassis.  Best to have it on its own.


Title: Re: Analog modulating a 1000 watt carrier class E rig
Post by: steve_qix on August 14, 2019, 06:46:07 PM
Oh, that is in a 7 inch high rack enclosure.  So, it is not very big at all, considering the power.


Title: Re: Analog modulating a 1000 watt carrier class E rig
Post by: Opcom on August 14, 2019, 07:02:03 PM
I like the front panel appearance. Timeless and unique.


Title: Re: Analog modulating a 1000 watt carrier class E rig
Post by: KD6VXI on August 14, 2019, 07:42:56 PM
45 volts at 250 amps eh?

For 24 fets?  Lol


--Shane
KD6VXI


Title: Re: Analog modulating a 1000 watt carrier class E rig
Post by: ka1tdq on August 16, 2019, 01:48:23 PM
I was testing it on the air this morning when something went wrong with my drain power supply. I think the transformer might've blown. I'll need to unrack it and see.

For the testing I was able to do, the audio ranges from crystal clear to very distorted depending on tuning. I sample the audio coming off the transmitter and send it to my headphones.

The last step I had done was to pull the variac out of the input and plug the drain power supply directly into the wall. It worked for a few seconds and then something went wrong.

Jon


Title: Re: Analog modulating a 1000 watt carrier class E rig
Post by: ka1tdq on August 16, 2019, 08:45:09 PM
I'm amazed it worked as well as it did. My rectifier PVC cap assembly had all loose hardware and the common ground stud was loose (all not good when drawing lots of current).

I'm going to completely redo the power supply and get rid of the clip leads and bungee cable holding the volt meter.

Jon


Title: Re: Analog modulating a 1000 watt carrier class E rig
Post by: steve_qix on August 17, 2019, 08:14:17 AM
I'd be surprised if the transformer is the issue.  Most likely a rectifier.

The rectifiers for this type of duty will get *HOT* and MUST be heat sunk.  Otherwise they will melt down internally.

I use various bridges ranging from 50A bridges to 200A bridges.  High voltage is not a requirement - in fact, lower voltage is better (less loss).

Heat sinking of the rectifiers is mandatory.  The heat sink I use with the 50A bridge rectifier for my 24 FET rig gets fairly warm after a long transmission.

I attached a picture.  You can see the rectifier heat sink near the bottom of the picture, near the power transformer and filter capacitors (48000uF total).

(http://www.classeradio.com/rig_back_3.jpg)


Title: Re: Analog modulating a 1000 watt carrier class E rig
Post by: ka1tdq on August 17, 2019, 06:39:17 PM
Thanks for the tips!

Here's a block that DigiKey has in stock that is 60A at 600V:

https://www.digikey.com/product-detail/en/vishay-semiconductor-diodes-division/VS-UFH60BA65/VS-UFH60BA65GI-ND/9477549 (https://www.digikey.com/product-detail/en/vishay-semiconductor-diodes-division/VS-UFH60BA65/VS-UFH60BA65GI-ND/9477549)

I can bolt the connections to the rectifier with this model.

Also, I was using my current transformer in a voltage doubling circuit (half the current available). I'm going to upgrade to an Antek version that will use a full wave bridge.  

Jon


Title: Re: Analog modulating a 1000 watt carrier class E rig
Post by: steve_qix on August 17, 2019, 08:44:01 PM
Those will definitely work.

If you want to spend less money, I use these:

https://www.mouser.com/ProductDetail/Comchip-Technology/GBPC5006-G?qs=sGAEpiMZZMtQ8nqTKtFS%2FAgQizVVuOFlTMPKXRfKYJU%3D

and these:

https://www.mouser.com/ProductDetail/GeneSiC-Semiconductor/KBPC5006T?qs=sGAEpiMZZMtQ8nqTKtFS%2FKGlmTW84eZIGDm4lDGEeghFuiQYvB%252BPRA%3D%3D


Title: Re: Analog modulating a 1000 watt carrier class E rig
Post by: ka1tdq on August 25, 2019, 11:01:05 PM
I don't have anything done on the inside yet, but this is how it'll look.

I'm just waiting on the heat sink to arrive and to order the transformer.

Jon


Title: Re: Analog modulating a 1000 watt carrier class E rig
Post by: Opcom on August 26, 2019, 02:04:26 PM
Nice. the color's right! reminds me of a garage shop battery charger!


Title: Re: Analog modulating a 1000 watt carrier class E rig
Post by: ka1tdq on September 02, 2019, 03:49:26 PM
Ouchy.

Drill bit broke and went into the palm of my hand. Iím ok though. Itís the simple power supplies that get you.

Jon


Title: Re: Analog modulating a 1000 watt carrier class E rig
Post by: Opcom on September 11, 2019, 11:15:31 AM
How did that happen? Hope it heals up well.


Title: Re: Analog modulating a 1000 watt carrier class E rig
Post by: K1JJ on September 11, 2019, 12:46:32 PM
Ouchy.

Drill bit broke and went into the palm of my hand. Iím ok though. Itís the simple power supplies that get you.

Jon

Jon,

The same thing hapened to me in 1972.  I drilled a broken bit right into my left hand at the base of the thumb using a hand drill. Nasty ripped up flesh and required a lot of stitches in emergency. Still have scars.  It complements my deep scars on the other hand when I got belted with 800VDC the same year.

I've not made that mistake again since...  using a dull bit that required pushing so hard that the bit snapped. I didn't know drill bits could be sharpened back then. Since then I bought a drill bit sharpener called "Dr. Drill" and keep 'em sharp.

Are you left-handed?  

T


Title: Re: Analog modulating a 1000 watt carrier class E rig
Post by: ka1tdq on September 11, 2019, 03:34:32 PM
Very similar situation here. I was pushing a dull drill bit hard with my hand 'out of the way.' It snapped, the broken bit still in the drill made a gash in my hand and the broken bit lodged itself inside my palm about 3/4" in a separate hole. There's the brief second after it's over and you look down at the damage with a drill bit sticking out of your hand and you wonder, "Did I just do that?"

It is healing up nicely with no stitches required. X-rays show no material still inside. And yes, I am left handed.

I got the transformer in for the power supply and now have all the parts. Hopefully I'll finish it soon.

Jon


Title: Re: Analog modulating a 1000 watt carrier class E rig
Post by: K1JJ on September 11, 2019, 06:58:33 PM
Wow, Jon, you are really lucky.

The broken sides of the bit are like a meat grinder. Could have torn up muscle, tendons, nerve pathways, veins, etc. Amazing you didn't need any stitches.

After all the many, many dangerous things I've done and risks I've taken, I am convinced we all have a guardian angel looking out for us. In your case he (she) wanted to teach you a good lesson and let you off hook easily.... :-)

These days I use a drill press, usually lock work down that can potentially spin, and use heavy leather welding gloves. I also have a bandsaw, lathe and other dangerous machines that can take fingers and hands clean off, so glad I learned early in life to think everything out carefully before jumping in.

I took a metal class in high school and noticed that the teacher was missing a finger from a router accident.  I think as hams we put much more emphasis on avoiding electric shock rather than machine accidents.  Young, new builders need to think about this more.

T


Title: Re: Analog modulating a 1000 watt carrier class E rig
Post by: ka1tdq on September 18, 2019, 11:47:26 PM
I have everything all mounted. Now, just wiring it up.

Jon


Title: Re: Analog modulating a 1000 watt carrier class E rig
Post by: Opcom on September 19, 2019, 10:29:33 PM
What is in the top left corner in the image? Pressure sensor?


Title: Re: Analog modulating a 1000 watt carrier class E rig
Post by: ka1tdq on September 20, 2019, 01:07:31 PM
It is a pressure sensor. The chassis used to be a helium compressor that I gutted.

I probably should've removed it, but I just painted over the front of the meter.

Jon


Title: Re: Analog modulating a 1000 watt carrier class E rig
Post by: ka1tdq on September 22, 2019, 12:49:06 PM
Well, here it is.  It's definitely beefier than my old one. Now just to hook it up and retest.

Jon


Title: Re: Analog modulating a 1000 watt carrier class E rig
Post by: ka1tdq on September 22, 2019, 06:42:30 PM
There's 400 watts on the dipole. I haven't finished fine tuning yet. Getting this far was frustrating enough because my hand would sometimes rotate the 'Wave Select' knob by accident and I'd switch between a sine wave and square wave. Everything would get thrown off and I'd go through a bunch of changes to figure out why, only to keep coming back to that waveform selection.

Anyway, enough for today. I'm going out for pizza.

Jon


Title: Re: Analog modulating a 1000 watt carrier class E rig
Post by: WD5JKO on September 23, 2019, 03:54:34 PM

John,

  I always look forward to your updates.

Will be interesting on what the efficiency turns out to be.

You know, 400 watts (or 500 watts DC input) is a lot of CO2 from the power plant!  :-*

Jim
Wd5JKO


Title: Re: Analog modulating a 1000 watt carrier class E rig
Post by: ka1tdq on September 23, 2019, 04:00:25 PM
In the metro Phoenix area, we have the largest nuclear power plant in the country. Zero green house emissions sir...  ;)

That scope picture was taken with a lower drain voltage. I need to ease it up and tweak the controls to get it to where it should be. I just stopped by Harbor Freight too to pick up a few extra multimeters. It'll be easier for me to calculate efficiency with 5 digital meters all reading something at once.

Jon


Title: Re: Analog modulating a 1000 watt carrier class E rig
Post by: steve_qix on September 23, 2019, 10:19:09 PM
Not bad !! Looking forward to further updates.


Title: Re: Analog modulating a 1000 watt carrier class E rig
Post by: ka1tdq on September 24, 2019, 04:16:28 AM
Iím waiting on a couple doorknob capacitors to arrive from Ukraine. Right now Iím fully meshed on the loading capacitor and this will give me some options upward. Iím sitting right around 3400pf.

Seems like a lot. But, to continue testing I want the options if things go that way. I can move lower too with the current mix of doorknobs I have.

Jon


Title: Re: Analog modulating a 1000 watt carrier class E rig
Post by: steve_qix on September 24, 2019, 10:39:32 PM
Hmm... That seems like a lot of capacitance for loading on 75 meters.  Do you have 4 modules of 6 FETs each, all in series with 1:1 output transformers (and combined out of phase of course)? 



Title: Re: Analog modulating a 1000 watt carrier class E rig
Post by: ka1tdq on September 25, 2019, 08:23:07 AM
Yes to all that.

I have a 1500pf cap, a 1000pf cap and a 900pf variable cap fully meshed all in parallel on the output. Drain voltage is low right now too, so maybe that's playing a part. Another possibility is that I could have something squirrely going on with the antenna. Long story short, I think I have an intermittent PL-259 splice outside.

I'll put the rig on a dummy load in the shack to see how it behaves. The only problem is that the cantenna gets warm pretty quick.

Jon


Title: Re: Analog modulating a 1000 watt carrier class E rig
Post by: KB2WIG on September 26, 2019, 07:06:37 AM


Put the cantenna in the fridge.


KLC


Title: Re: Analog modulating a 1000 watt carrier class E rig
Post by: ka1tdq on September 26, 2019, 09:53:49 AM
Just make sure the oil residue doesn't get on the leftovers.

Jon


Title: Re: Analog modulating a 1000 watt carrier class E rig
Post by: ka1tdq on September 26, 2019, 11:18:21 PM
Here's my test setup and the current waveforms. I'm limited in the amount of testing time I have due to dummy load heating. I need to wait overnight for the oil to cool.

Right now I'm at around 1350pf on the loading capacitor. I probably do have something wrong with my antenna. I'll do the rest of the testing using the cantenna.

This is at 325 watts carrier and about 80% efficiency. The waveform starts to get distorted as I raise drain voltage above 30 volts. I tried to tweak everything to compensate but my dummy load was at its limit. I'll try again tomorrow.

Jon


Title: Re: Analog modulating a 1000 watt carrier class E rig
Post by: ka1tdq on September 27, 2019, 12:50:41 PM
Here are the waveforms for 400 watts carrier with 33 vdc on the drains. I still keep coming back to 80% efficiency though, unless there's some error in the way I'm measuring it. The good thing though is that current draw from each of the 4 buses is consistent.

The waveforms look pretty good though. I'm not sure how to improve on them.

Now I need to fix my antenna and maybe belch out some modulated RF!

Jon


Title: Re: Analog modulating a 1000 watt carrier class E rig
Post by: WD5JKO on September 27, 2019, 05:16:50 PM
I still keep coming back to 80% efficiency though, unless there's some error in the way I'm measuring it. The good thing though is that current draw from each of the 4 buses is consistent.
/quote]

Jon,

  The peak Drain voltage should be about  ~ 4X the Drain supply. Also, try DC coupling the scope so you can see if the FET's are saturating close to ground when turned on. If the Gate drive has slow rise and fall times, then that will degrade efficiency as well. Does anything other than the Cantenna get hot?

Good Stuff!
Jim
Wd5JKO


Title: Re: Analog modulating a 1000 watt carrier class E rig
Post by: ka1tdq on September 27, 2019, 06:56:36 PM
The heat sink does get a little warm, but not too bad.

I fixed what I thought was the problem with my antenna but SWR swings wildly.  When it's there, it's there... and the waveforms look beautiful. But then things start going haywire with SWR and power jumping all around. I noticed it too with my rice box on 20 meters. I use the same feedline for it and SWR has jumping way high there too.

I need to buy new coax for this setup. When I opened up the trouble spot in the coax, I noticed that water had seeped in along the shield for a long way.

Jon


Title: Re: Analog modulating a 1000 watt carrier class E rig
Post by: vk3alk on September 27, 2019, 07:14:40 PM
Hi Jon....

Its best to test into a Dummy Load.....
Ebay has some high powered 50 ohm non inductive resistors....will have a look later on and see whats around...

Can you post some pictures of your gate waveforms ....
One when there is no voltage applied to the Drains and one with voltage...
Could you overlap them a little too ... makes it easier to see what the timing is etc:

Just looking for things like Duty Cycle .... voltage levels etc:


Wayne


Title: Re: Analog modulating a 1000 watt carrier class E rig
Post by: vk3alk on September 27, 2019, 09:50:26 PM
Maybe for a quick 50R Dummy Load something like this:

https://www.ebay.com/itm/10-OHM-100W-Non-Inductive-High-Power-Resistor-100-Watts-x1/202394779668?hash=item2f1fab4014:g:LtIAAOSwhkRWg5eo

Order 5 of them .....put in a box with a couple of fans.....
The only thing its from China so maybe order one first and check the inductance and order more from the same supplier....


Wayne



Title: Re: Analog modulating a 1000 watt carrier class E rig
Post by: ka1tdq on September 28, 2019, 12:35:03 AM
Hey Wayne,

My little cantenna actually does a pretty good job. It heats up and slows me down, but that could be a good thing.

I'll do a little more scope stuff in a little bit, but I really want to get my antenna problem nailed down first. I know I can get pretty waveforms with the rig right now, so I just want to do more testing with the dipole. Heating up dummy loads gets pretty boring after a while.

I'm drawn to this too because in between SWR excursions, the waveforms looked superb!  Even better than with the dummy load. Trust me on this one.

https://www.youtube.com/watch?v=yM25-lz1Yms (https://www.youtube.com/watch?v=yM25-lz1Yms)

Jon


Title: Re: Analog modulating a 1000 watt carrier class E rig
Post by: WD5JKO on September 28, 2019, 07:52:02 AM
Yes, "Something Wonderful" Love that video.  ;D


Jon,

   You could take this idea to a higher level. Add salt to lower impedance, and add water to raise the impedance.
 
https://www.flickr.com/photos/g6sfp/2781053531/in/photostream/

Need more key down 400 watt time, use a bigger bucket!

Jim
Wd5JKO


Title: Re: Analog modulating a 1000 watt carrier class E rig
Post by: ka1tdq on September 28, 2019, 01:48:48 PM
It's funny but I'm almost a step ahead of you. I already have the bucket and it'd be easy just to add salt water!

Actually, I was using the bucket was for secondary containment.

I stopped at HRO this morning and got 100' of LMR400. I'll install it tomorrow. My kid's birthday party today.

Jon


Title: Re: Analog modulating a 1000 watt carrier class E rig
Post by: ka1tdq on September 28, 2019, 07:31:07 PM
...and I let the smoke out. I'm not sure of exactly what, but it looks like one of the drivers. I'm thinking the problem all along was parasitics.

I replaced my antenna feed line with a near perfect SWR, tuned up at 300 watts with a nice safe waveform, unkeyed... When I keyed up again the waveforms were completely scattered with smoke coming from something.

I'm thinking I should've put those 300 ohm resistors inline with each driver.

Jon


Title: Re: Analog modulating a 1000 watt carrier class E rig
Post by: w8khk on September 29, 2019, 01:36:41 AM
You might want to consider adding one of these:

http://www.classeradio.com/efficiency_meter_rev_f.pdf


Title: Re: Analog modulating a 1000 watt carrier class E rig
Post by: ka1tdq on September 29, 2019, 10:13:12 AM
The 5-meter method does just as well.

At some point I'll pull the heat sink assembly, replace the damaged components and put in some parasitic suppression.

Jon


Title: Re: Analog modulating a 1000 watt carrier class E rig
Post by: w8khk on September 29, 2019, 10:37:32 AM
The 5-meter method does just as well.

The idea here is that the QIX board monitors AND SHUTS DOWN immediately upon overload.  No human can respond to an overload that quickly while monitoring meters visually.  The alternative: ordering from Mouser or Digi-key and soldering OFTEN.  Certainly worth a careful look at this option.


Title: Re: Analog modulating a 1000 watt carrier class E rig
Post by: ka1tdq on September 29, 2019, 11:34:28 AM
Oh


Title: Re: Analog modulating a 1000 watt carrier class E rig
Post by: Opcom on October 02, 2019, 12:43:46 AM
Ugh! Oily cantennas!! You'd think Heathkit could have offered something with a bellows.


Title: Re: Analog modulating a 1000 watt carrier class E rig
Post by: steve_qix on October 02, 2019, 10:46:35 PM

I'm thinking I should've put those 300 ohm resistors inline with each driver.

Jon

Yes, those resistors have to be there, or the likelyhood of parasitics is quite high.



Title: Re: Analog modulating a 1000 watt carrier class E rig
Post by: ka1tdq on October 03, 2019, 09:49:29 AM
It'll require a rebuild of the heat sink assembly.

Something to note, the transzorbs protected two of four mosfet modules. Once I cut out the transzorbs, the dead short went away from the drain bus for those two modules. Something else went as well with the remaining two modules.

After all this, I still had a sporadically fluctuating SWR problem when using my rice box. I had a coax splice in the shack that was intermittently making connection. I could shake the coax at the splice and SWR would jump all over the place. Once I put a new connector on, the problem went away. I'm sure this contributed to the parasitic problem as well.

It's a shame though to blow up a rig over a PL-259.

Jon


Title: Re: Analog modulating a 1000 watt carrier class E rig
Post by: ka1tdq on October 03, 2019, 07:45:50 PM
Actually I take that back. I forgot that I installed two transzorbs per mosfet module. Once I cut them all out and did resistance checks, I realized that the drains were protected. So, all seems ok and I'll just need to solder on more transzorbs.

But, in the time since I thought I blew up my class E rig, I converted my 75 meter dipole into a 40 meter delta loop and bought an Icom 7300. What a nice rig!

Jon
AMfone - Dedicated to Amplitude Modulation on the Amateur Radio Bands