PWM inductors for higher impedances

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PWM inductors for higher impedances

Postby n4lta » Thu May 26, 2011 8:52 pm

Anyone ever tries to use the heavy duty air core indutcors used for speaker crossovers for PWM filtering? They are wound with 15 guage wire with air cores and are compact. The larger inductances required for higher impedance filters make solenoid single layer inductors very large. Parts express has a large number of sizes and also large high voltage polypro capacitors.

I am looking at a 100 watt amp and the filter will need to be around 20 ohms for a 2.5 amp load at 50 volts.
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Re: PWM inductors for higher impedances

Postby Gilly » Fri May 27, 2011 2:04 am

Hi Pat

Don't know too much about those inductors you mentioned.

For 100Watts I use 30Volts @ 4 Amps appox....
That gives you around 7 Ohms and makes the Inductor windings much less....you could just copy Steves output filter and things would be close enough probably .... :D
Other advantages are it gives you more headroom providing more positive modulation....Something I like to look at on the CRO.......
In Australia our power ratings are much less than you guys.....My HT Voltage is 135 Volts and my Carrier Voltage is 30 Volts so I have heaps of positive available....
Also keeps your Class E waveform down too....even though the 11n90 FET is rated at 900Volts....
In some of my TX's I use IRF840 that are rated at 600Volts so a carrier level of 30 Volts keeps things under control....

Did you get those 74OL6010 ?


Wayne
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Re: PWM inductors for higher impedances

Postby n4lta » Fri May 27, 2011 10:34 am

No - Something is screwed up. The tracking comes back with an attempted deliver a week ago (I was there and it did not happen) and now says delivery not made. There is no number to call or email address to ask what is going on. I filed a dispute with Ali whatever and they say I have to wait 14 days to hear from the sender on the dispute. Not sure what is going on.

It appears that everything stopped last Friday and there is no available methode to communicate with the shipper. The only telephone number is a Chinese number.

EMS Full Shipment 16 May 2011 Tracking
Date Location Status
21 May 2011 12:23 UNITED STATES OF AMERICA 29302 Attempted delivery
21 May 2011 10:24 UNITED STATES OF AMERICA 29306 Arrival at Delivery Office
20 May 2011 16:15 UNITED STATES OF AMERICA USJFKA Arrival at Sorting Center
17 May 2011 20:47 SHENZHEN Despatch from Sorting Center
17 May 2011 20:04 SHENZHEN Arrival at Sorting Center
17 May 2011 19:29 SHENZHEN Despatch from Sorting Center
17 May 2011 19:16 SHENZHEN Posting
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Re: PWM inductors for higher impedances

Postby Gilly » Fri May 27, 2011 7:47 pm

Hi Pat

Looks like they sent it quickly after they received your payment....and they ( delivery people ) acknowledge not delivering it to you for some reason.....
Maybe wait another week and start complaining again via ALI Web site....
It may hopefully appear at your door step in the next couple of days !
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Re: PWM inductors for higher impedances

Postby n4lta » Mon May 30, 2011 8:37 pm

They (the shipper) say that they don't have a complete address but they give no method of communicating with the shipper. I finally have a telephone number and will try to call tomarrow.
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Re: PWM inductors for higher impedances

Postby n4lta » Tue May 31, 2011 5:18 pm

The US Postal Service had them at my location and did not notify me. The parts look great.
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Re: PWM inductors for higher impedances

Postby steve_qix » Sat Jul 16, 2011 7:15 am

As long as the inductors are completely air core, they should work. Any iron will certainly saturate, as these inductors are not designed to handle any unbalanced DC.

Let us know the outcome.

Regards,

Steve
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Re: PWM inductors for higher impedances

Postby n4lta » Mon Jul 18, 2011 10:05 am

I think these will probably work. They are air core wound with #15 wire and are multi turn.

BTW Bocen Technology found me 25 of the Fairchild 11N90 FETs (the new version) for $2 each. The shipping brings them up to $3 each.

Pat
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Re: PWM inductors for higher impedances

Postby steve_qix » Mon Jul 18, 2011 3:10 pm

n4lta wrote:I think these will probably work. They are air core wound with #15 wire and are multi turn.

BTW Bocen Technology found me 25 of the Fairchild 11N90 FETs (the new version) for $2 each. The shipping brings them up to $3 each.

Pat
N4LTA

What is the exact part number of the "new" FQA11N90s you got. The FQA11N90C is a different part, and won't work at the same levels as the standard FQA11N90. There are a lot of FQA11N90C parts out there, and they are usually pretty cheap.
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Re: PWM inductors for higher impedances

Postby n4lta » Mon Jul 18, 2011 8:08 pm

Marked

FQA
11N90

1A17CJ is the lot #

Seem to be the correct part
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