Yes, a Q of 7 is OK at that impedance if harmonics at only -24db are
acceptable.
Multi-Op stations are more interested in -35 to -40db.
With such low Q one should make use of Pi-L.
73
Peter
-----Original Message-----
From: jeff millar [mailto:jeff@wa1hco.net]
Sent: Montag, 19. Oktober 2009 02:43
To: DF3KV
Cc: amps@contesting.com
Subject: Re: [Amps] tank calculations - need input
If you want a Q of 12, values of about 430pf, 4.6 uH, 1900 pF do work.
But you really only need a Q of about 7 to comfortably match 1000 Ohms
to 50 Ohms. The Q of 12 rule was created in the days of higher
impedance tubes.
jeff, wa1hco
DF3KV wrote:
> I don´t see anything wrong how you set the pi components.
> All values are the same with my calculations.
> 1000pf for C2 plus 1500pf total added should load nicely with 5µH on 80m
at
> a Q of 12.
> What kind of safety choke are you using and did you try 20m where you
don´t
> need additional fixed C?
>
> 73
> Peter
>
> -----Original Message-----
> From: amps-bounces@contesting.com [mailto:amps-bounces@contesting.com] On
> Behalf Of ka1mwp
> Sent: Sonntag, 18. Oktober 2009 14:02
> To: 'Roger'
> Cc: Amps@contesting.com
> Subject: Re: [Amps] tank calculations - need input
>
> Comet CV05c - 650n/5
>
> Hooked up to a GME LC200 inductance meter
>
> Watching the capacitance as I turn, not that it matters..
> The issue is why does the amp need LOTS AND LOTS of capacitance :)
>
>
>
> -----Original Message-----
> From: amps-bounces@contesting.com [mailto:amps-bounces@contesting.com]
> On Behalf Of Roger
> Sent: Saturday, October 17, 2009 10:45 PM
> Cc: Amps@contesting.com
> Subject: Re: [Amps] tank calculations - need input
>
>
>
> ka1mwp wrote:
>
>> Well, I can see turning it clockwise lowers the value...as I sit here
>> and double check...
>>
>> Out is increasing value (CCW) it gets looser and opens the plates...
>>
>>
>>
> That's backwards to mine. Does the screw have right or left hand
> threads. If CCW would be backing the screw out it's pushing the plates
> closer together. The screw should be held in place so it can only turn
> which pushes or pulls the plates in the opposite direction you'd think
> the screw would be moving.
>
> 73
>
> Roger (K8RI)
>
>> -----Original Message-----
>> From: amps-bounces@contesting.com [mailto:amps-bounces@contesting.com]
>> On Behalf Of Bill, W6WRT
>> Sent: Saturday, October 17, 2009 7:05 PM
>> To: Amps@contesting.com
>> Subject: Re: [Amps] tank calculations - need input
>>
>> ORIGINAL MESSAGE:
>>
>> On Sat, 17 Oct 2009 16:49:39 -0400, "ka1mwp" <ka1mwp@comcast.net>
>>
> wrote:
>
>>
>>
>>> its with the vacuum cap out all the way (max
>>> capacitance) and
>>>
>>>
>> REPLY:
>>
>> That's backwards. All the way out (unmeshed) is minimum capacitance.
>>
> Is
>
>> that
>> leading you the wrong way?
>>
>> 73, Bill W6WRT
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>>
>>
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