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Re: U3S /5W PA on 2M

 

Me too Glen!

I'm quite interested in the subject of using the U3S on 2 meters and
would welcome any information on mods, upgrades, etc. with that in
mind. I am following your thread here closely to see what it might
turn up.

I'm somewhat lost now as I have never seen Ft listed on a switching
FET datasheet. I can only guess Bill means to use a linear RF rated
FET, but as they are very different beasts I worry about trying to
retrofit on into a U3S without knowing what I'm doing.

73,
Paul N1BUG

On 08/09/2018 10:58 AM, Info wrote:
Bill,

I thought as much...will search for a better part.? I sure wish
someone would publish the mods

for 2M!!!

73

Glen K4KV



On 8/9/2018 09:28, J68HZ wrote:

I built my U3A for two meters about 2 years ago now and I opted to
use a replacement to the BS170 that has a much higher Ft¡­ I don¡¯t
recall what I used off-hand but it puts out much more power than
the BS170.? As I recall the equivalent Ft for the BS170 is about
100MHz (although I could be wrong because this is all by memory).?
Even a 2N3866 silicon NPN has an Ft of 800MHz¡­ and you can scan
the parts catalog for a MOSFET that has an Ft in the 500+MHz range
that would be a better choice.? Nothing against the BS170¡­ it¡¯s a
great little switch, but it just gives up the ghost a bit above
100²Ñ±á³ú¡­
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