[600MRG] WIMA capacitors AND substitutes

[D.J.J. Ring, Jr.]

Hello,

I don't see any previous discussion of the Russian LDMOS amplifiers.

Would you post where you ordered one from?

I don't know why I can't find the previous thread!

Thank you very much,

73

David N1EA WD2XSH/18



On Sat, Jan 6, 2018 at 3:35 PM, lstoskopf at cox.net lstoskopf at cox.net <
lstoskopf at cox.net> wrote:

> OK, going to jump back in here.  I've ordered on of the Russian LDMOS 500
> watt amps, water cooled.  Saves me from a bunch of mechanical work (have
> the tools, maybe not the smarts).  Tried to get them to sell me an amp with
> the Laird LF cores which I have instead of the 43 ones.  Didn't bite.  It
> should be here next week.  So will pull off the cores and replace with the
> Laird ones about the same size.  May use twice as many so it might work
> well at 136 kHz.  3 turns will give 520 ohms X2 at 500 kHz.       They put
> the blocking caps after the first set to take advantage of the higher Z
> there and thus lower current.   The schematic they provided shows 3 ea 0.1
> uF 630 V caps on each side.  Pulled up the specs on the TDK
> C4532X7R2J104K230KA chip from DigiKey.  At 500 kHz ESR is 0.05 Ohms,
> Reactance is a couple of ohms and with 1 A ripple gives a 10C degree temp
> rise.  (at 136 kHz 0.5A gives the same 10C rise).  500 watts should give
> about 3A.  They use 3 in parallel on each side for HF so I'm going to use 5
> or 6 to keep temps down.  Will let you know how this works out.
> http://w7ekb.com/mailman/listinfo/600mrg_w7ekb.com
>
> Not planning on running this much, at least until someone comes up with a
> way to measure EIRP! http://w7ekb.com/mailman/listinfo/600mrg_w7ekb.com
>
> N0UU http://w7ekb.com/mailman/listinfo/600mrg_w7ekb.com
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