Re: 144 mhz tuned input for a GG YC-156 ??
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From: [email protected] [mailto:[email protected]] On Behalf Of Robert W5AJ
Sent: Friday, January 05, 2024 11:21 PM
To: [email protected]
Subject: Re: [ham-amplifiers] 144 mhz tuned input for a GG YC-156 ?? ? Jim,?? is there public domain software program that helps with Pi network design? aka,? I'm looking at 8877 50Mhz project in 2024 On Fri, Jan 5, 2024 at 2:28?PM Jim VE7RF <jim.thom@...> wrote: YC-156 is good up to 150 mhz.? ? It will be used on 144 mhz.? ? Yes, the 8877 has a 38.5 pf? between cathode and grid....and is good up to 250 mhz.?? ? Question is.... how the hell do u make a tuned input for 144 mhz, with a whopping 92.5 pf of input C ?? ? With a conventional Pi tuned input....and an overall network Q of '4'? ?( input Q = 2.2)? ( output Q = 1.8)
It's then? C1 = 49.1 pf? ?L= .04 uh? ? C2 =? 56.1 pf? The input C is WAY more than the? required C2 value.? ?Note this is based on a 35 ohm input Z.?
...................................................................................................................................................................................................................................................................................................................................................................................... ? OK, here's what might work....increase the overall network Q to '8'? ? ( input Q =4.4)? ?( output Q = 3.6)? It's then C1 = 96.8 pf? ?L =? .02 uh? ?C2 = 114.4 pf? ? Note, this is based on a 35 ohm input Z.?? trying to fabricate a .02 uh inductor will be a trick. A straight piece of copper strap might just? work.? ? Jim? ?VE7RF
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