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ZakWolf

Tue Feb 16 2016, 07:46AM

Registered Member #3114 Joined: Sat Aug 14 2010, 08:33AM
Location:
Posts: 608

Alright, I have been here a long time and can say I have had hit and miss posts on here. I like 4hv and only come here and support this site and if i ask stupid questions im sorry.

To celebrate the purchase of my new oscilloscope I want to build a tiny, cool running, beautiful HFSSTC Class E coil.

Other then

and

What else is there for resources? Do I need to just read about RF amp. designs ?

Goals:

Higher the Mhz the better

Provide information for people like me

Fixed frequency

cool heatsinks ( happy fets)

I see mostly IRFP460's used... tell me is this a way better replacement ?

1/8 of the Rds!! 3x current !!!

Is Erik T, Using rectified mains ?

150v in?

Power Input? I have this

Or would mains work like Erik's 150v input (170v Smoothed)***

So What I gather is I need a fixed ossilation via crystal and I need to clean up the signal/ make it able to switch my

on and off, tune coil via L and C? Bring (force) switching to ZVS of course

Additionally, interrupters... Staccato? Class E sword streamers?

Dr. Slack

Tue Feb 16 2016, 10:49AM

Registered Member #72 Joined: Thu Feb 09 2006, 08:29AM
Location: UK St. Albans
Posts: 1659

Your Mouser link with 1/8th rds, just goes to the main site and not the component. I would have thought that rDS was relatively unimportant compared to switching energy if you want MOAR MHz.

ZakWolf

Tue Feb 16 2016, 04:19PM

Registered Member #3114 Joined: Sat Aug 14 2010, 08:33AM
Location:
Posts: 608

Dr. Slack wrote ...

Your Mouser link with 1/8th rds, just goes to the main site and not the component. I would have thought that rDS was relatively unimportant compared to switching energy if you want MOAR MHz.

Original post updated/fixed

Inducktion

Tue Feb 16 2016, 07:01PM

Registered Member #3637 Joined: Fri Jan 21 2011, 11:07PM
Location: Buffalo, NY
Posts: 1068

I don't know much about class E, but I do know that switching times and gate capacitance are the biggest factors in determining how fast a fet can switch on and off. At the speeds you're switching the fets RDSon becomes the lesser of the two evils, and switching losses will dominate how much power you dissipate.

Hell even the driver and just discharging and recharging the gate capacitance can dissipate a decent amount of RF power alone.

jdub1581hv

Tue Feb 16 2016, 09:30PM

Registered Member #55219 Joined: Tue Jun 09 2015, 11:21PM
Location:
Posts: 80

I too am diving into the class E and E/F(added harmonic filters, 2fo, 3fo, 5fo).
You forgot about Steve Wards class E S. Wards cESSTC

I was about to post the same topic, Mind if I piggyback?

For me however, I am looking into the lower F(res) 300khz - 600khz.

So here's what I found as the basic amp schematic:
E Schematic

I did find this online Class E Calculator Class E Calculator ..
More for Radio work, so should help you with the high(er) MHZ

However there are a few things that I am unsure about as many I see only use L1 and C1 in regards to TC's.
(Forgive my ignorance if this sounds dumb, still tons I have no Idea about..)

Are C2-L2 the switches values or actual components? Or the combination/reduction of both?

ZakWolf

Wed Feb 17 2016, 04:51AM

Registered Member #3114 Joined: Sat Aug 14 2010, 08:33AM
Location:
Posts: 608

jdub1581hv wrote ...

I too am diving into the class E and E/F(added harmonic filters, 2fo, 3fo, 5fo).
You forgot about Steve Wards class E S. Wards cESSTC

I was about to post the same topic, Mind if I piggyback?

For me however, I am looking into the lower F(res) 300khz - 600khz.

So here's what I found as the basic amp schematic:
E Schematic

You may Piggy Back. More the merry.

I was also looking for RF Amps schematics around the 4Mhz area and have very little

Edit: Give this a read

jdub1581hv

Wed Feb 17 2016, 08:59PM

Registered Member #55219 Joined: Tue Jun 09 2015, 11:21PM
Location:
Posts: 80

So I fixed the calculator link (forgot to put the http in) .. Sorry bout that.

Also here is another good read.. helped me out at least though it is geared more to class F
Class F and Inverse class F
Covers it all as far as getting the design down, switching behavior, filtering etc..
I'm leaning more to the E/F hybrid myself, as to be both efficient and powerful (F is less efficient, yet more power out from what I read.. but can reach 100% as well with precision parts and design).

And also, I think the impedance matching and component reduction finally started making sense last night. For me only being able to read online and not converse with live people (aside from here) has made this quite the adventure...

I have a couple Cree SiC Mosfets 900v 36a I want to use for this, but for now I'm too timid and don't enjoy $10 smoke rings.

So for now I have 3 CEFF630 mfets, 10a, 650v, low Ciss 800pf / Coss 150pf , and rds of .27 - .4ohms
I'm a little worried about the dissipation only being 35W...

There also seems to be a lot of different ways to deal with drive signal, but I'm debating Res. Feedback vs Xtal .. I don't think the 4046 pll would have any problems, but I've read it has its own intrinsic flaws...

Still curious if anyone could give some design guidelines as far as where to start.. Start with resonator, fets, frequency? I've got about 15 resonators to choose from, starting: 1/2"dia x 3"
-> 6"dia x 24" , with a rough F range of 6mhz down to 150khz ...

jdub1581hv

Wed Feb 17 2016, 11:33PM

Registered Member #55219 Joined: Tue Jun 09 2015, 11:21PM
Location:
Posts: 80

Another good read..
]hfe0111_firas.pdf[/file]

ZakWolf

Thu Feb 18 2016, 12:08AM

Registered Member #3114 Joined: Sat Aug 14 2010, 08:33AM
Location:
Posts: 608

jdub1581hv wrote ...

So I fixed the calculator link (forgot to put the http in) .. Sorry bout that.

Also here is another good read.. helped me out at least though it is geared more to class F
Class F and Inverse class F
Covers it all as far as getting the design down, switching behavior, filtering etc..
I'm leaning more to the E/F hybrid myself, as to be both efficient and powerful (F is less efficient, yet more power out from what I read.. but can reach 100% as well with precision parts and design).

And also, I think the impedance matching and component reduction finally started making sense last night. For me only being able to read online and not converse with live people (aside from here) has made this quite the adventure...

I have a couple Cree SiC Mosfets 900v 36a I want to use for this, but for now I'm too timid and don't enjoy $10 smoke rings.

So for now I have 3 CEFF630 mfets, 10a, 650v, low Ciss 800pf / Coss 150pf , and rds of .27 - .4ohms
I'm a little worried about the dissipation only being 35W...

There also seems to be a lot of different ways to deal with drive signal, but I'm debating Res. Feedback vs Xtal .. I don't think the 4046 pll would have any problems, but I've read it has its own intrinsic flaws...

Still curious if anyone could give some design guidelines as far as where to start.. Start with resonator, fets, frequency? I've got about 15 resonators to choose from, starting: 1/2"dia x 3"
-> 6"dia x 24" , with a rough F range of 6mhz down to 150khz ...

jdub1581hv wrote ...

Another good read..

Thanks I have been working so I havent had time to read till now. I found this its extensive and seems really organized [quote]
Another good read..

its also Class E/F design

Inducktion

Thu Feb 18 2016, 01:41AM

Registered Member #3637 Joined: Fri Jan 21 2011, 11:07PM
Location: Buffalo, NY
Posts: 1068

jdub1581hv, you have to be careful with SiC Fet's.

Pay heavy attention to the voltage they can handle on their gates.... They do not tolerate negative swings more than like, -5 volts before they start to have issues/break down.

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