[Amps] Tuned input board on SB-220

[Karl-Arne Markström]

Actually the value of 20 pF/meter (-j27) is also quoted at several places in my 1970 edition along with 13 pF/meter.
Presumably these values result in "reasonable" cathode circuit Q's (2 - 3) with the input impedances 
(in the region of 100 ohms) of then commonly used grounded grid tubes (see i.a. the table on page 191).

73/

Karl-Arne
SM0AOM



----- Original Message ----- 
From: "Peter Chadwick" <g3rzp at g3rzp.wanadoo.co.uk>
To: "Bill Fuqua" <wlfuqu00 at uky.edu>; "Roger D Johnson" <n1rj at adelphia.net>; <garyschafer at comcast.net>
Cc: <amps at contesting.com>
Sent: Saturday, March 25, 2006 10:11 AM
Subject: Re: [Amps] Tuned input board on SB-220


> What is the rationale for the magic 13pF/metre? It works out as -j41....and please don't say 'because it's in Bill Orr's book!'
> 73
> Peter G3RZP
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