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

To: amps@contesting.com
Subject: Re: [Amps] 200-ohm tank and "un-un" in HF amp design?
From: Jim W7RY <w7ry@centurytel.net>
Reply-to: w7ry@centurytel.net
Date: Sun, 20 Oct 2013 06:31:44 -0700
List-post: <amps@contesting.com">mailto:amps@contesting.com>
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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