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Re: [Amps] 200-ohm tank and "un-un" in HF amp design?

To: w7ry@centurytel.net, amps@contesting.com
Subject: Re: [Amps] 200-ohm tank and "un-un" in HF amp design?
From: Jim Barber <audioguy@q.com>
Reply-to: Jim Barber <audioguy@q.com>
Date: Sun, 20 Oct 2013 08:28:58 -0700
List-post: <amps@contesting.com">mailto:amps@contesting.com>
1500 watts
4kV, 625mA
Single 8877 at around 4000 ohms plate impedance in AB2.

Tnx,
Jim N7CXI


Sent from mobile wireless



-------- Original message --------
From: Jim W7RY <w7ry@centurytel.net> 
Date: 10/20/2013  6:31 AM  (GMT-08:00) 
To: amps@contesting.com 
Subject: Re: [Amps] 200-ohm tank and "un-un" in HF amp design? 
 
What kind of power?  What plate voltage and current on the tube?

73
Jim W7RY


On 10/20/2013 12:51 AM, Jim Barber wrote:
> Assuming adequate core/wire sizing and airflow, can anyone think of a 
> solid reason *not* to design a legal-limit HF amp output tank for 200 
> ohms, then use a 4:1 "un-un" transformer to step it down to 50?
>
> I'm curious because doing so would bring the loading cap requirement 
> for a 4000-ohm plate impedance down to under 1000pF at 1.8 mHz, which 
> can be done with a large air variable alone.
>
> Note: Yes, I know it *has* been done already, but I'm asking for 
> opinions as to whether you think it should be.
>
> Thanks and 73,
> Jim N7CXI
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> Amps mailing list
> Amps@contesting.com
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>
>

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