[AMPS] More on B&W 850 as tank coil
km1h@juno.com
km1h@juno.com
Tue, 9 Feb 1999 10:53:17 -0500
I have no idea what thought patterns at B&W produced that tank coil. As I
mentioned to you earlier the 850 was advertised for 2500 to 5000 Ohms. A
reason for the rather strange 20-10M values could have been to permit the
use of large air variables where the minimum C is often very high; seems
I mentioned that to you also.
The Johnson 153-13 7KV variable is 45-245pf as an example.
The 7KV 153-12 is 31-151pf
73 Carl KM1H
On Mon, 8 Feb 1999 21:36:26 -0600 Jon Ogden <jono@enteract.com> writes:
>
>>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?
>
>73,
>
>Jon
>KE9NA
>
>
>
>
>-------------------------------------
>Jon Ogden
>KE9NA
>
>http://www.qsl.net/ke9na <--- CHECK IT OUT! It's been
>updated!!!!!
>
>
>"A life lived in fear is a life half lived."
>
>
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>
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