[Top] [All Lists]

[AMPS] More on B&W 850 as tank coil

To: <>
Subject: [AMPS] More on B&W 850 as tank coil
From: (Jon Ogden)
Date: Mon, 8 Feb 1999 21:36:26 -0600
>Band           L
>80            13.6
>40             6.5
>20             1.75
>15             1.0
>10             0.8
>Now I have just created a spreadsheet for Pi-networks where I can vary 
>the tube impedance and the Q of the Pi-net.  I can't find a combination 
>where the L needed in the circuit matches what B&W provides.  It is 
>certainly screwed up for my 4-1000A impedance of around 5000 Ohms.

Ok, I did some more figuring.  I decided that no law says that the value 
of Q has to stay fixed from band to band.  So, I did some playing in the 
spreadsheet and found the following given the values of L above:

Frequency         Q         C1           C2         L

3.75 MHz         18       141.4 pF      1135 pF     13.7 nH
7.15 MHz         20          82 pF       691 pF     6.52 nH
14.2 MHz         38          78 pF       747 pF    1.776 nH
21.2 MHz         45        61.5 pF       597 pF      1.0 nH
28.3 MHz         42          43 pF       416 pF      0.8 nH

So, I guess it is possible to use real world value components in this 
example, but the Qs get awfully high.

I guess I am asking for some help here because it seems like the Q values 
get a bit high.  Is this a good matching circuit design or not?



Jon Ogden
KE9NA    <--- CHECK IT OUT!  It's been updated!!!!!

"A life lived in fear is a life half lived."

FAQ on WWW:     
Administrative requests:

<Prev in Thread] Current Thread [Next in Thread>