Re: RF power chain mods and improvements..
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What about using (2) 2SC1973s for the drivers and BF199s as the pre-drivers?
Marco - KG5PRT?
On Sat, May 19, 2018, 5:08 PM ajparent1/KB1GMX < kb1gmx@...> wrote: Hi Arv,
Yes. But there is no need for that.? We need under 1W to drive a IRF510
to 10 ore more watts.? Actually I've used 2W in the WA1EBY (pp pair of
IRF510s at 28V) for more than 50W.? To get 2W I used a 2SC779 and it
as not working hard at all.
Work backwards if you want 10W assume worst case 10DB (Likely 13-16)
so to get 1 you only need 1W if its 13DB its .5W, and so on.? The trick is
to load the gate so the IRF510 is stable? and make it up with drive power.
The bigger parts like the IRF520 and 530 are sill power limited due to heat transfer
though it is better the problem is efficiency keeping it above 45% so your not
equally heating the device for every watt you put out as the dissipated power is
your limit. And IRF510 at 3A 12V is handling 36W, if the efficieny is 50%
your seeing 18W.? Save for its needs 24V to do that and then you are at 72W
input and 36 out (eff=.5).? The part is 4+ amp capable so that not a limit. The
limit is the 36W of heat.? One must deliver that power to the load not as heat.
Allison
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