Just for hell of it since I was set up -- I built that network in Genesys
and let it optimize for what Rload and Cload was optimum 2 to 29.75 mHz.
First looked at network using 50 ohms R load and let Cload optimize - and
was less than 2:1 SWR from 2 to 29.75mHz with C load 154 pfd.
Then let it optimize Both R load and Cload and it came up with R load 43
ohms , Cload 160 pfd SWR less than 1.6:1 from 2 - 28.25 mHz and 2.3:1 at
29.75.
FWIW - if you set R load at 50 ohms and leave the inductors at the given
values , then let the C values optimize , you get better than 1.2:1 SWR 2 -
29.75 mHz -- C input(was 120) 71.5 pfd , C2 (was 250) 136 pfd
and tube is 60 pfd.
As a common sense test I normally always put 10 to 20 nhy lead inductance in
the shunt caps (total of one half to one inch of lead length) - but 10 or 20
nhy did not degrade response - slight change in caps values of a pfd or two
which is expected.
Hank K7HP
=====
----- Original Message -----
From: "Carl" <km1h@jeremy.mv.com>
To: "Vic K2VCO" <k2vco.vic@gmail.com>; <amps@contesting.com>
Sent: Thursday, August 09, 2012 1:42 PM
Subject: [Amps] 4CX1500B
> You can also give the YU1AW circuit a try where he came up with a 160-10
> broadband input for a tetrode not named.
>
> It is a 120pf input cap to ground, a series 345nH coil, 250pf cap to
> ground and a series 308nH coil. I have the coil dimensions if needed. The
> terminating resistor is 50 Ohms.
>
> Disclaimer: I havent tried or analyzed it.
>
> Carl
> KM1H
>
>
>
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