Re: LF: EA5DOM LF tests

[Alberto Martinez <ea4ghb@gmail.com>]

Hi all,

Congrats Luis, I see the audio PA works great. This weekend try to listen.

73!

Alberto-EA4GHB

2016-09-07 14:18 GMT+02:00 DK7FC <selberdenken@posteo.de>:

Hi Luis,

Am 07.09.2016 13:33, schrieb VIGILANT Luis Fernández:

Ideas wellcome ! :-)

 

I like the W1YD design http://www.w1vd.com/137-500-500WTX.pdf

Yes, a very typical design.
I would use a different output transformer, with a higher AL value (>= 4000 nH/N^2). Then you need less primary and secondary turns. This can become relevant when using high power at low voltages. But 50W is almost nothing. The 240-77 is fine for several 100W.
And your FETs have a very high input capacitance. This will warm up the 7667 at 137 kHz i think. And the rise times will rise :-) And so the switching losses are higher.....

For 50W at 13.8V i would use an IRFZ48N or so, something with Ciss < 2 nF. This will work well with the 7667 then. At 50W you can use a normal 13.8 V power supply.

The unregulated power supply will quickly lead to complaints from certain OMs as you know :-) So you need to add a regulation or very BIG caps.

48V is a good supply voltage for a PA. I would then tend to use IRFP260N FETs. But then you will need a better driver, something like TC4420 or even IXDD614CI :-)

73, Stefan

 

Don't need the keyer and would use an ICL7667 as dual mosfet driver

For the mosfets what I have here is a couple of IRFP3206

 

I have a linear transformer with 2x24V outputs. Can be good for an unregulated 48V supply

This is what the audio PA is using now 

 

73 de Luis

EA5DOM

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De: owner-rsgb_lf_group@blacksheep.org [mailto:owner-rsgb_lf_group@blacksheep.org] En nombre de DK7FC
Enviado el: miércoles, 07 de septiembre de 2016 12:58
Para: rsgb_lf_group@blacksheep.org
Asunto: Re: LF: EA5DOM LF tests

Am 07.09.2016 12:16, schrieb VIGILANT Luis Fernández:

 

Time for a D class PA  ;-)

Output filter and transformer core is already here, so should be easy to get some 50w or more (10dB)

That sounds good. Can you show a schematic that you want to build up? Which voltage, which FETs, which driver?

73, Stefan